| How fio works |
| ------------- |
| |
| The first step in getting fio to simulate a desired I/O workload, is writing a |
| job file describing that specific setup. A job file may contain any number of |
| threads and/or files -- the typical contents of the job file is a *global* |
| section defining shared parameters, and one or more job sections describing the |
| jobs involved. When run, fio parses this file and sets everything up as |
| described. If we break down a job from top to bottom, it contains the following |
| basic parameters: |
| |
| `I/O type`_ |
| |
| Defines the I/O pattern issued to the file(s). We may only be reading |
| sequentially from this file(s), or we may be writing randomly. Or even |
| mixing reads and writes, sequentially or randomly. |
| Should we be doing buffered I/O, or direct/raw I/O? |
| |
| `Block size`_ |
| |
| In how large chunks are we issuing I/O? This may be a single value, |
| or it may describe a range of block sizes. |
| |
| `I/O size`_ |
| |
| How much data are we going to be reading/writing. |
| |
| `I/O engine`_ |
| |
| How do we issue I/O? We could be memory mapping the file, we could be |
| using regular read/write, we could be using splice, async I/O, or even |
| SG (SCSI generic sg). |
| |
| `I/O depth`_ |
| |
| If the I/O engine is async, how large a queuing depth do we want to |
| maintain? |
| |
| |
| `Target file/device`_ |
| |
| How many files are we spreading the workload over. |
| |
| `Threads, processes and job synchronization`_ |
| |
| How many threads or processes should we spread this workload over. |
| |
| The above are the basic parameters defined for a workload, in addition there's a |
| multitude of parameters that modify other aspects of how this job behaves. |
| |
| |
| Command line options |
| -------------------- |
| |
| .. option:: --debug=type |
| |
| Enable verbose tracing `type` of various fio actions. May be ``all`` for all types |
| or individual types separated by a comma (e.g. ``--debug=file,mem`` will |
| enable file and memory debugging). Currently, additional logging is |
| available for: |
| |
| *process* |
| Dump info related to processes. |
| *file* |
| Dump info related to file actions. |
| *io* |
| Dump info related to I/O queuing. |
| *mem* |
| Dump info related to memory allocations. |
| *blktrace* |
| Dump info related to blktrace setup. |
| *verify* |
| Dump info related to I/O verification. |
| *all* |
| Enable all debug options. |
| *random* |
| Dump info related to random offset generation. |
| *parse* |
| Dump info related to option matching and parsing. |
| *diskutil* |
| Dump info related to disk utilization updates. |
| *job:x* |
| Dump info only related to job number x. |
| *mutex* |
| Dump info only related to mutex up/down ops. |
| *profile* |
| Dump info related to profile extensions. |
| *time* |
| Dump info related to internal time keeping. |
| *net* |
| Dump info related to networking connections. |
| *rate* |
| Dump info related to I/O rate switching. |
| *compress* |
| Dump info related to log compress/decompress. |
| *steadystate* |
| Dump info related to steadystate detection. |
| *helperthread* |
| Dump info related to the helper thread. |
| *zbd* |
| Dump info related to support for zoned block devices. |
| *?* or *help* |
| Show available debug options. |
| |
| .. option:: --parse-only |
| |
| Parse options only, don't start any I/O. |
| |
| .. option:: --merge-blktrace-only |
| |
| Merge blktraces only, don't start any I/O. |
| |
| .. option:: --output=filename |
| |
| Write output to file `filename`. |
| |
| .. option:: --output-format=format |
| |
| Set the reporting `format` to `normal`, `terse`, `json`, or `json+`. Multiple |
| formats can be selected, separated by a comma. `terse` is a CSV based |
| format. `json+` is like `json`, except it adds a full dump of the latency |
| buckets. |
| |
| .. option:: --bandwidth-log |
| |
| Generate aggregate bandwidth logs. |
| |
| .. option:: --minimal |
| |
| Print statistics in a terse, semicolon-delimited format. |
| |
| .. option:: --append-terse |
| |
| Print statistics in selected mode AND terse, semicolon-delimited format. |
| **Deprecated**, use :option:`--output-format` instead to select multiple |
| formats. |
| |
| .. option:: --terse-version=version |
| |
| Set terse `version` output format (default 3, or 2 or 4 or 5). |
| |
| .. option:: --version |
| |
| Print version information and exit. |
| |
| .. option:: --help |
| |
| Print a summary of the command line options and exit. |
| |
| .. option:: --cpuclock-test |
| |
| Perform test and validation of internal CPU clock. |
| |
| .. option:: --crctest=[test] |
| |
| Test the speed of the built-in checksumming functions. If no argument is |
| given, all of them are tested. Alternatively, a comma separated list can |
| be passed, in which case the given ones are tested. |
| |
| .. option:: --cmdhelp=command |
| |
| Print help information for `command`. May be ``all`` for all commands. |
| |
| .. option:: --enghelp=[ioengine[,command]] |
| |
| List all commands defined by `ioengine`, or print help for `command` |
| defined by `ioengine`. If no `ioengine` is given, list all |
| available ioengines. |
| |
| .. option:: --showcmd=jobfile |
| |
| Convert `jobfile` to a set of command-line options. |
| |
| .. option:: --readonly |
| |
| Turn on safety read-only checks, preventing writes and trims. The |
| ``--readonly`` option is an extra safety guard to prevent users from |
| accidentally starting a write or trim workload when that is not desired. |
| Fio will only modify the device under test if |
| `rw=write/randwrite/rw/randrw/trim/randtrim/trimwrite` is given. This |
| safety net can be used as an extra precaution. |
| |
| .. option:: --eta=when |
| |
| Specifies when real-time ETA estimate should be printed. `when` may be |
| `always`, `never` or `auto`. `auto` is the default, it prints ETA |
| when requested if the output is a TTY. `always` disregards the output |
| type, and prints ETA when requested. `never` never prints ETA. |
| |
| .. option:: --eta-interval=time |
| |
| By default, fio requests client ETA status roughly every second. With |
| this option, the interval is configurable. Fio imposes a minimum |
| allowed time to avoid flooding the console, less than 250 msec is |
| not supported. |
| |
| .. option:: --eta-newline=time |
| |
| Force a new line for every `time` period passed. When the unit is omitted, |
| the value is interpreted in seconds. |
| |
| .. option:: --status-interval=time |
| |
| Force a full status dump of cumulative (from job start) values at `time` |
| intervals. This option does *not* provide per-period measurements. So |
| values such as bandwidth are running averages. When the time unit is omitted, |
| `time` is interpreted in seconds. Note that using this option with |
| ``--output-format=json`` will yield output that technically isn't valid |
| json, since the output will be collated sets of valid json. It will need |
| to be split into valid sets of json after the run. |
| |
| .. option:: --section=name |
| |
| Only run specified section `name` in job file. Multiple sections can be specified. |
| The ``--section`` option allows one to combine related jobs into one file. |
| E.g. one job file could define light, moderate, and heavy sections. Tell |
| fio to run only the "heavy" section by giving ``--section=heavy`` |
| command line option. One can also specify the "write" operations in one |
| section and "verify" operation in another section. The ``--section`` option |
| only applies to job sections. The reserved *global* section is always |
| parsed and used. |
| |
| .. option:: --alloc-size=kb |
| |
| Allocate additional internal smalloc pools of size `kb` in KiB. The |
| ``--alloc-size`` option increases shared memory set aside for use by fio. |
| If running large jobs with randommap enabled, fio can run out of memory. |
| Smalloc is an internal allocator for shared structures from a fixed size |
| memory pool and can grow to 16 pools. The pool size defaults to 16MiB. |
| |
| NOTE: While running :file:`.fio_smalloc.*` backing store files are visible |
| in :file:`/tmp`. |
| |
| .. option:: --warnings-fatal |
| |
| All fio parser warnings are fatal, causing fio to exit with an |
| error. |
| |
| .. option:: --max-jobs=nr |
| |
| Set the maximum number of threads/processes to support to `nr`. |
| NOTE: On Linux, it may be necessary to increase the shared-memory |
| limit (:file:`/proc/sys/kernel/shmmax`) if fio runs into errors while |
| creating jobs. |
| |
| .. option:: --server=args |
| |
| Start a backend server, with `args` specifying what to listen to. |
| See `Client/Server`_ section. |
| |
| .. option:: --daemonize=pidfile |
| |
| Background a fio server, writing the pid to the given `pidfile` file. |
| |
| .. option:: --client=hostname |
| |
| Instead of running the jobs locally, send and run them on the given `hostname` |
| or set of `hostname`\s. See `Client/Server`_ section. |
| |
| .. option:: --remote-config=file |
| |
| Tell fio server to load this local `file`. |
| |
| .. option:: --idle-prof=option |
| |
| Report CPU idleness. `option` is one of the following: |
| |
| **calibrate** |
| Run unit work calibration only and exit. |
| |
| **system** |
| Show aggregate system idleness and unit work. |
| |
| **percpu** |
| As **system** but also show per CPU idleness. |
| |
| .. option:: --inflate-log=log |
| |
| Inflate and output compressed `log`. |
| |
| .. option:: --trigger-file=file |
| |
| Execute trigger command when `file` exists. |
| |
| .. option:: --trigger-timeout=time |
| |
| Execute trigger at this `time`. |
| |
| .. option:: --trigger=command |
| |
| Set this `command` as local trigger. |
| |
| .. option:: --trigger-remote=command |
| |
| Set this `command` as remote trigger. |
| |
| .. option:: --aux-path=path |
| |
| Use the directory specified by `path` for generated state files instead |
| of the current working directory. |
| |
| Any parameters following the options will be assumed to be job files, unless |
| they match a job file parameter. Multiple job files can be listed and each job |
| file will be regarded as a separate group. Fio will :option:`stonewall` |
| execution between each group. |
| |
| |
| Job file format |
| --------------- |
| |
| As previously described, fio accepts one or more job files describing what it is |
| supposed to do. The job file format is the classic ini file, where the names |
| enclosed in [] brackets define the job name. You are free to use any ASCII name |
| you want, except *global* which has special meaning. Following the job name is |
| a sequence of zero or more parameters, one per line, that define the behavior of |
| the job. If the first character in a line is a ';' or a '#', the entire line is |
| discarded as a comment. |
| |
| A *global* section sets defaults for the jobs described in that file. A job may |
| override a *global* section parameter, and a job file may even have several |
| *global* sections if so desired. A job is only affected by a *global* section |
| residing above it. |
| |
| The :option:`--cmdhelp` option also lists all options. If used with a `command` |
| argument, :option:`--cmdhelp` will detail the given `command`. |
| |
| See the `examples/` directory for inspiration on how to write job files. Note |
| the copyright and license requirements currently apply to `examples/` files. |
| |
| So let's look at a really simple job file that defines two processes, each |
| randomly reading from a 128MiB file: |
| |
| .. code-block:: ini |
| |
| ; -- start job file -- |
| [global] |
| rw=randread |
| size=128m |
| |
| [job1] |
| |
| [job2] |
| |
| ; -- end job file -- |
| |
| As you can see, the job file sections themselves are empty as all the described |
| parameters are shared. As no :option:`filename` option is given, fio makes up a |
| `filename` for each of the jobs as it sees fit. On the command line, this job |
| would look as follows:: |
| |
| $ fio --name=global --rw=randread --size=128m --name=job1 --name=job2 |
| |
| |
| Let's look at an example that has a number of processes writing randomly to |
| files: |
| |
| .. code-block:: ini |
| |
| ; -- start job file -- |
| [random-writers] |
| ioengine=libaio |
| iodepth=4 |
| rw=randwrite |
| bs=32k |
| direct=0 |
| size=64m |
| numjobs=4 |
| ; -- end job file -- |
| |
| Here we have no *global* section, as we only have one job defined anyway. We |
| want to use async I/O here, with a depth of 4 for each file. We also increased |
| the buffer size used to 32KiB and define numjobs to 4 to fork 4 identical |
| jobs. The result is 4 processes each randomly writing to their own 64MiB |
| file. Instead of using the above job file, you could have given the parameters |
| on the command line. For this case, you would specify:: |
| |
| $ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4 |
| |
| When fio is utilized as a basis of any reasonably large test suite, it might be |
| desirable to share a set of standardized settings across multiple job files. |
| Instead of copy/pasting such settings, any section may pull in an external |
| :file:`filename.fio` file with *include filename* directive, as in the following |
| example:: |
| |
| ; -- start job file including.fio -- |
| [global] |
| filename=/tmp/test |
| filesize=1m |
| include glob-include.fio |
| |
| [test] |
| rw=randread |
| bs=4k |
| time_based=1 |
| runtime=10 |
| include test-include.fio |
| ; -- end job file including.fio -- |
| |
| .. code-block:: ini |
| |
| ; -- start job file glob-include.fio -- |
| thread=1 |
| group_reporting=1 |
| ; -- end job file glob-include.fio -- |
| |
| .. code-block:: ini |
| |
| ; -- start job file test-include.fio -- |
| ioengine=libaio |
| iodepth=4 |
| ; -- end job file test-include.fio -- |
| |
| Settings pulled into a section apply to that section only (except *global* |
| section). Include directives may be nested in that any included file may contain |
| further include directive(s). Include files may not contain [] sections. |
| |
| |
| Environment variables |
| ~~~~~~~~~~~~~~~~~~~~~ |
| |
| Fio also supports environment variable expansion in job files. Any sub-string of |
| the form ``${VARNAME}`` as part of an option value (in other words, on the right |
| of the '='), will be expanded to the value of the environment variable called |
| `VARNAME`. If no such environment variable is defined, or `VARNAME` is the |
| empty string, the empty string will be substituted. |
| |
| As an example, let's look at a sample fio invocation and job file:: |
| |
| $ SIZE=64m NUMJOBS=4 fio jobfile.fio |
| |
| .. code-block:: ini |
| |
| ; -- start job file -- |
| [random-writers] |
| rw=randwrite |
| size=${SIZE} |
| numjobs=${NUMJOBS} |
| ; -- end job file -- |
| |
| This will expand to the following equivalent job file at runtime: |
| |
| .. code-block:: ini |
| |
| ; -- start job file -- |
| [random-writers] |
| rw=randwrite |
| size=64m |
| numjobs=4 |
| ; -- end job file -- |
| |
| Fio ships with a few example job files, you can also look there for inspiration. |
| |
| Reserved keywords |
| ~~~~~~~~~~~~~~~~~ |
| |
| Additionally, fio has a set of reserved keywords that will be replaced |
| internally with the appropriate value. Those keywords are: |
| |
| **$pagesize** |
| |
| The architecture page size of the running system. |
| |
| **$mb_memory** |
| |
| Megabytes of total memory in the system. |
| |
| **$ncpus** |
| |
| Number of online available CPUs. |
| |
| These can be used on the command line or in the job file, and will be |
| automatically substituted with the current system values when the job is |
| run. Simple math is also supported on these keywords, so you can perform actions |
| like:: |
| |
| size=8*$mb_memory |
| |
| and get that properly expanded to 8 times the size of memory in the machine. |
| |
| |
| Job file parameters |
| ------------------- |
| |
| This section describes in details each parameter associated with a job. Some |
| parameters take an option of a given type, such as an integer or a |
| string. Anywhere a numeric value is required, an arithmetic expression may be |
| used, provided it is surrounded by parentheses. Supported operators are: |
| |
| - addition (+) |
| - subtraction (-) |
| - multiplication (*) |
| - division (/) |
| - modulus (%) |
| - exponentiation (^) |
| |
| For time values in expressions, units are microseconds by default. This is |
| different than for time values not in expressions (not enclosed in |
| parentheses). The following types are used: |
| |
| |
| Parameter types |
| ~~~~~~~~~~~~~~~ |
| |
| **str** |
| String: A sequence of alphanumeric characters. |
| |
| **time** |
| Integer with possible time suffix. Without a unit value is interpreted as |
| seconds unless otherwise specified. Accepts a suffix of 'd' for days, 'h' for |
| hours, 'm' for minutes, 's' for seconds, 'ms' (or 'msec') for milliseconds and |
| 'us' (or 'usec') for microseconds. For example, use 10m for 10 minutes. |
| |
| .. _int: |
| |
| **int** |
| Integer. A whole number value, which may contain an integer prefix |
| and an integer suffix: |
| |
| [*integer prefix*] **number** [*integer suffix*] |
| |
| The optional *integer prefix* specifies the number's base. The default |
| is decimal. *0x* specifies hexadecimal. |
| |
| The optional *integer suffix* specifies the number's units, and includes an |
| optional unit prefix and an optional unit. For quantities of data, the |
| default unit is bytes. For quantities of time, the default unit is seconds |
| unless otherwise specified. |
| |
| With :option:`kb_base`\=1000, fio follows international standards for unit |
| prefixes. To specify power-of-10 decimal values defined in the |
| International System of Units (SI): |
| |
| * *K* -- means kilo (K) or 1000 |
| * *M* -- means mega (M) or 1000**2 |
| * *G* -- means giga (G) or 1000**3 |
| * *T* -- means tera (T) or 1000**4 |
| * *P* -- means peta (P) or 1000**5 |
| |
| To specify power-of-2 binary values defined in IEC 80000-13: |
| |
| * *Ki* -- means kibi (Ki) or 1024 |
| * *Mi* -- means mebi (Mi) or 1024**2 |
| * *Gi* -- means gibi (Gi) or 1024**3 |
| * *Ti* -- means tebi (Ti) or 1024**4 |
| * *Pi* -- means pebi (Pi) or 1024**5 |
| |
| With :option:`kb_base`\=1024 (the default), the unit prefixes are opposite |
| from those specified in the SI and IEC 80000-13 standards to provide |
| compatibility with old scripts. For example, 4k means 4096. |
| |
| For quantities of data, an optional unit of 'B' may be included |
| (e.g., 'kB' is the same as 'k'). |
| |
| The *integer suffix* is not case sensitive (e.g., m/mi mean mebi/mega, |
| not milli). 'b' and 'B' both mean byte, not bit. |
| |
| Examples with :option:`kb_base`\=1000: |
| |
| * *4 KiB*: 4096, 4096b, 4096B, 4ki, 4kib, 4kiB, 4Ki, 4KiB |
| * *1 MiB*: 1048576, 1mi, 1024ki |
| * *1 MB*: 1000000, 1m, 1000k |
| * *1 TiB*: 1099511627776, 1ti, 1024gi, 1048576mi |
| * *1 TB*: 1000000000, 1t, 1000m, 1000000k |
| |
| Examples with :option:`kb_base`\=1024 (default): |
| |
| * *4 KiB*: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB |
| * *1 MiB*: 1048576, 1m, 1024k |
| * *1 MB*: 1000000, 1mi, 1000ki |
| * *1 TiB*: 1099511627776, 1t, 1024g, 1048576m |
| * *1 TB*: 1000000000, 1ti, 1000mi, 1000000ki |
| |
| To specify times (units are not case sensitive): |
| |
| * *D* -- means days |
| * *H* -- means hours |
| * *M* -- means minutes |
| * *s* -- or sec means seconds (default) |
| * *ms* -- or *msec* means milliseconds |
| * *us* -- or *usec* means microseconds |
| |
| If the option accepts an upper and lower range, use a colon ':' or |
| minus '-' to separate such values. See :ref:`irange <irange>`. |
| If the lower value specified happens to be larger than the upper value |
| the two values are swapped. |
| |
| .. _bool: |
| |
| **bool** |
| Boolean. Usually parsed as an integer, however only defined for |
| true and false (1 and 0). |
| |
| .. _irange: |
| |
| **irange** |
| Integer range with suffix. Allows value range to be given, such as |
| 1024-4096. A colon may also be used as the separator, e.g. 1k:4k. If the |
| option allows two sets of ranges, they can be specified with a ',' or '/' |
| delimiter: 1k-4k/8k-32k. Also see :ref:`int <int>`. |
| |
| **float_list** |
| A list of floating point numbers, separated by a ':' character. |
| |
| With the above in mind, here follows the complete list of fio job parameters. |
| |
| |
| Units |
| ~~~~~ |
| |
| .. option:: kb_base=int |
| |
| Select the interpretation of unit prefixes in input parameters. |
| |
| **1000** |
| Inputs comply with IEC 80000-13 and the International |
| System of Units (SI). Use: |
| |
| - power-of-2 values with IEC prefixes (e.g., KiB) |
| - power-of-10 values with SI prefixes (e.g., kB) |
| |
| **1024** |
| Compatibility mode (default). To avoid breaking old scripts: |
| |
| - power-of-2 values with SI prefixes |
| - power-of-10 values with IEC prefixes |
| |
| See :option:`bs` for more details on input parameters. |
| |
| Outputs always use correct prefixes. Most outputs include both |
| side-by-side, like:: |
| |
| bw=2383.3kB/s (2327.4KiB/s) |
| |
| If only one value is reported, then kb_base selects the one to use: |
| |
| **1000** -- SI prefixes |
| |
| **1024** -- IEC prefixes |
| |
| .. option:: unit_base=int |
| |
| Base unit for reporting. Allowed values are: |
| |
| **0** |
| Use auto-detection (default). |
| **8** |
| Byte based. |
| **1** |
| Bit based. |
| |
| |
| Job description |
| ~~~~~~~~~~~~~~~ |
| |
| .. option:: name=str |
| |
| ASCII name of the job. This may be used to override the name printed by fio |
| for this job. Otherwise the job name is used. On the command line this |
| parameter has the special purpose of also signaling the start of a new job. |
| |
| .. option:: description=str |
| |
| Text description of the job. Doesn't do anything except dump this text |
| description when this job is run. It's not parsed. |
| |
| .. option:: loops=int |
| |
| Run the specified number of iterations of this job. Used to repeat the same |
| workload a given number of times. Defaults to 1. |
| |
| .. option:: numjobs=int |
| |
| Create the specified number of clones of this job. Each clone of job |
| is spawned as an independent thread or process. May be used to setup a |
| larger number of threads/processes doing the same thing. Each thread is |
| reported separately; to see statistics for all clones as a whole, use |
| :option:`group_reporting` in conjunction with :option:`new_group`. |
| See :option:`--max-jobs`. Default: 1. |
| |
| |
| Time related parameters |
| ~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| .. option:: runtime=time |
| |
| Tell fio to terminate processing after the specified period of time. It |
| can be quite hard to determine for how long a specified job will run, so |
| this parameter is handy to cap the total runtime to a given time. When |
| the unit is omitted, the value is interpreted in seconds. |
| |
| .. option:: time_based |
| |
| If set, fio will run for the duration of the :option:`runtime` specified |
| even if the file(s) are completely read or written. It will simply loop over |
| the same workload as many times as the :option:`runtime` allows. |
| |
| .. option:: startdelay=irange(time) |
| |
| Delay the start of job for the specified amount of time. Can be a single |
| value or a range. When given as a range, each thread will choose a value |
| randomly from within the range. Value is in seconds if a unit is omitted. |
| |
| .. option:: ramp_time=time |
| |
| If set, fio will run the specified workload for this amount of time before |
| logging any performance numbers. Useful for letting performance settle |
| before logging results, thus minimizing the runtime required for stable |
| results. Note that the ``ramp_time`` is considered lead in time for a job, |
| thus it will increase the total runtime if a special timeout or |
| :option:`runtime` is specified. When the unit is omitted, the value is |
| given in seconds. |
| |
| .. option:: clocksource=str |
| |
| Use the given clocksource as the base of timing. The supported options are: |
| |
| **gettimeofday** |
| :manpage:`gettimeofday(2)` |
| |
| **clock_gettime** |
| :manpage:`clock_gettime(2)` |
| |
| **cpu** |
| Internal CPU clock source |
| |
| cpu is the preferred clocksource if it is reliable, as it is very fast (and |
| fio is heavy on time calls). Fio will automatically use this clocksource if |
| it's supported and considered reliable on the system it is running on, |
| unless another clocksource is specifically set. For x86/x86-64 CPUs, this |
| means supporting TSC Invariant. |
| |
| .. option:: gtod_reduce=bool |
| |
| Enable all of the :manpage:`gettimeofday(2)` reducing options |
| (:option:`disable_clat`, :option:`disable_slat`, :option:`disable_bw_measurement`) plus |
| reduce precision of the timeout somewhat to really shrink the |
| :manpage:`gettimeofday(2)` call count. With this option enabled, we only do |
| about 0.4% of the :manpage:`gettimeofday(2)` calls we would have done if all |
| time keeping was enabled. |
| |
| .. option:: gtod_cpu=int |
| |
| Sometimes it's cheaper to dedicate a single thread of execution to just |
| getting the current time. Fio (and databases, for instance) are very |
| intensive on :manpage:`gettimeofday(2)` calls. With this option, you can set |
| one CPU aside for doing nothing but logging current time to a shared memory |
| location. Then the other threads/processes that run I/O workloads need only |
| copy that segment, instead of entering the kernel with a |
| :manpage:`gettimeofday(2)` call. The CPU set aside for doing these time |
| calls will be excluded from other uses. Fio will manually clear it from the |
| CPU mask of other jobs. |
| |
| |
| Target file/device |
| ~~~~~~~~~~~~~~~~~~ |
| |
| .. option:: directory=str |
| |
| Prefix filenames with this directory. Used to place files in a different |
| location than :file:`./`. You can specify a number of directories by |
| separating the names with a ':' character. These directories will be |
| assigned equally distributed to job clones created by :option:`numjobs` as |
| long as they are using generated filenames. If specific `filename(s)` are |
| set fio will use the first listed directory, and thereby matching the |
| `filename` semantic (which generates a file for each clone if not |
| specified, but lets all clones use the same file if set). |
| |
| See the :option:`filename` option for information on how to escape "``:``" |
| characters within the directory path itself. |
| |
| Note: To control the directory fio will use for internal state files |
| use :option:`--aux-path`. |
| |
| .. option:: filename=str |
| |
| Fio normally makes up a `filename` based on the job name, thread number, and |
| file number (see :option:`filename_format`). If you want to share files |
| between threads in a job or several |
| jobs with fixed file paths, specify a `filename` for each of them to override |
| the default. If the ioengine is file based, you can specify a number of files |
| by separating the names with a ':' colon. So if you wanted a job to open |
| :file:`/dev/sda` and :file:`/dev/sdb` as the two working files, you would use |
| ``filename=/dev/sda:/dev/sdb``. This also means that whenever this option is |
| specified, :option:`nrfiles` is ignored. The size of regular files specified |
| by this option will be :option:`size` divided by number of files unless an |
| explicit size is specified by :option:`filesize`. |
| |
| Each colon in the wanted path must be escaped with a ``\`` |
| character. For instance, if the path is :file:`/dev/dsk/foo@3,0:c` then you |
| would use ``filename=/dev/dsk/foo@3,0\:c`` and if the path is |
| :file:`F:\\filename` then you would use ``filename=F\:\filename``. |
| |
| On Windows, disk devices are accessed as :file:`\\\\.\\PhysicalDrive0` for |
| the first device, :file:`\\\\.\\PhysicalDrive1` for the second etc. |
| Note: Windows and FreeBSD prevent write access to areas |
| of the disk containing in-use data (e.g. filesystems). |
| |
| The filename "`-`" is a reserved name, meaning *stdin* or *stdout*. Which |
| of the two depends on the read/write direction set. |
| |
| .. option:: filename_format=str |
| |
| If sharing multiple files between jobs, it is usually necessary to have fio |
| generate the exact names that you want. By default, fio will name a file |
| based on the default file format specification of |
| :file:`jobname.jobnumber.filenumber`. With this option, that can be |
| customized. Fio will recognize and replace the following keywords in this |
| string: |
| |
| **$jobname** |
| The name of the worker thread or process. |
| **$clientuid** |
| IP of the fio process when using client/server mode. |
| **$jobnum** |
| The incremental number of the worker thread or process. |
| **$filenum** |
| The incremental number of the file for that worker thread or |
| process. |
| |
| To have dependent jobs share a set of files, this option can be set to have |
| fio generate filenames that are shared between the two. For instance, if |
| :file:`testfiles.$filenum` is specified, file number 4 for any job will be |
| named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum` |
| will be used if no other format specifier is given. |
| |
| If you specify a path then the directories will be created up to the |
| main directory for the file. So for example if you specify |
| ``filename_format=a/b/c/$jobnum`` then the directories a/b/c will be |
| created before the file setup part of the job. If you specify |
| :option:`directory` then the path will be relative that directory, |
| otherwise it is treated as the absolute path. |
| |
| .. option:: unique_filename=bool |
| |
| To avoid collisions between networked clients, fio defaults to prefixing any |
| generated filenames (with a directory specified) with the source of the |
| client connecting. To disable this behavior, set this option to 0. |
| |
| .. option:: opendir=str |
| |
| Recursively open any files below directory `str`. |
| |
| .. option:: lockfile=str |
| |
| Fio defaults to not locking any files before it does I/O to them. If a file |
| or file descriptor is shared, fio can serialize I/O to that file to make the |
| end result consistent. This is usual for emulating real workloads that share |
| files. The lock modes are: |
| |
| **none** |
| No locking. The default. |
| **exclusive** |
| Only one thread or process may do I/O at a time, excluding all |
| others. |
| **readwrite** |
| Read-write locking on the file. Many readers may |
| access the file at the same time, but writes get exclusive access. |
| |
| .. option:: nrfiles=int |
| |
| Number of files to use for this job. Defaults to 1. The size of files |
| will be :option:`size` divided by this unless explicit size is specified by |
| :option:`filesize`. Files are created for each thread separately, and each |
| file will have a file number within its name by default, as explained in |
| :option:`filename` section. |
| |
| |
| .. option:: openfiles=int |
| |
| Number of files to keep open at the same time. Defaults to the same as |
| :option:`nrfiles`, can be set smaller to limit the number simultaneous |
| opens. |
| |
| .. option:: file_service_type=str |
| |
| Defines how fio decides which file from a job to service next. The following |
| types are defined: |
| |
| **random** |
| Choose a file at random. |
| |
| **roundrobin** |
| Round robin over opened files. This is the default. |
| |
| **sequential** |
| Finish one file before moving on to the next. Multiple files can |
| still be open depending on :option:`openfiles`. |
| |
| **zipf** |
| Use a *Zipf* distribution to decide what file to access. |
| |
| **pareto** |
| Use a *Pareto* distribution to decide what file to access. |
| |
| **normal** |
| Use a *Gaussian* (normal) distribution to decide what file to |
| access. |
| |
| **gauss** |
| Alias for normal. |
| |
| For *random*, *roundrobin*, and *sequential*, a postfix can be appended to |
| tell fio how many I/Os to issue before switching to a new file. For example, |
| specifying ``file_service_type=random:8`` would cause fio to issue |
| 8 I/Os before selecting a new file at random. For the non-uniform |
| distributions, a floating point postfix can be given to influence how the |
| distribution is skewed. See :option:`random_distribution` for a description |
| of how that would work. |
| |
| .. option:: ioscheduler=str |
| |
| Attempt to switch the device hosting the file to the specified I/O scheduler |
| before running. |
| |
| .. option:: create_serialize=bool |
| |
| If true, serialize the file creation for the jobs. This may be handy to |
| avoid interleaving of data files, which may greatly depend on the filesystem |
| used and even the number of processors in the system. Default: true. |
| |
| .. option:: create_fsync=bool |
| |
| :manpage:`fsync(2)` the data file after creation. This is the default. |
| |
| .. option:: create_on_open=bool |
| |
| If true, don't pre-create files but allow the job's open() to create a file |
| when it's time to do I/O. Default: false -- pre-create all necessary files |
| when the job starts. |
| |
| .. option:: create_only=bool |
| |
| If true, fio will only run the setup phase of the job. If files need to be |
| laid out or updated on disk, only that will be done -- the actual job contents |
| are not executed. Default: false. |
| |
| .. option:: allow_file_create=bool |
| |
| If true, fio is permitted to create files as part of its workload. If this |
| option is false, then fio will error out if |
| the files it needs to use don't already exist. Default: true. |
| |
| .. option:: allow_mounted_write=bool |
| |
| If this isn't set, fio will abort jobs that are destructive (e.g. that write) |
| to what appears to be a mounted device or partition. This should help catch |
| creating inadvertently destructive tests, not realizing that the test will |
| destroy data on the mounted file system. Note that some platforms don't allow |
| writing against a mounted device regardless of this option. Default: false. |
| |
| .. option:: pre_read=bool |
| |
| If this is given, files will be pre-read into memory before starting the |
| given I/O operation. This will also clear the :option:`invalidate` flag, |
| since it is pointless to pre-read and then drop the cache. This will only |
| work for I/O engines that are seek-able, since they allow you to read the |
| same data multiple times. Thus it will not work on non-seekable I/O engines |
| (e.g. network, splice). Default: false. |
| |
| .. option:: unlink=bool |
| |
| Unlink the job files when done. Not the default, as repeated runs of that |
| job would then waste time recreating the file set again and again. Default: |
| false. |
| |
| .. option:: unlink_each_loop=bool |
| |
| Unlink job files after each iteration or loop. Default: false. |
| |
| .. option:: zonemode=str |
| |
| Accepted values are: |
| |
| **none** |
| The :option:`zonerange`, :option:`zonesize`, |
| :option `zonecapacity` and option:`zoneskip` |
| parameters are ignored. |
| **strided** |
| I/O happens in a single zone until |
| :option:`zonesize` bytes have been transferred. |
| After that number of bytes has been |
| transferred processing of the next zone |
| starts. :option `zonecapacity` is ignored. |
| **zbd** |
| Zoned block device mode. I/O happens |
| sequentially in each zone, even if random I/O |
| has been selected. Random I/O happens across |
| all zones instead of being restricted to a |
| single zone. The :option:`zoneskip` parameter |
| is ignored. :option:`zonerange` and |
| :option:`zonesize` must be identical. |
| |
| .. option:: zonerange=int |
| |
| Size of a single zone. See also :option:`zonesize` and |
| :option:`zoneskip`. |
| |
| .. option:: zonesize=int |
| |
| For :option:`zonemode` =strided, this is the number of bytes to |
| transfer before skipping :option:`zoneskip` bytes. If this parameter |
| is smaller than :option:`zonerange` then only a fraction of each zone |
| with :option:`zonerange` bytes will be accessed. If this parameter is |
| larger than :option:`zonerange` then each zone will be accessed |
| multiple times before skipping to the next zone. |
| |
| For :option:`zonemode` =zbd, this is the size of a single zone. The |
| :option:`zonerange` parameter is ignored in this mode. |
| |
| |
| .. option:: zonecapacity=int |
| |
| For :option:`zonemode` =zbd, this defines the capacity of a single zone, |
| which is the accessible area starting from the zone start address. |
| This parameter only applies when using :option:`zonemode` =zbd in |
| combination with regular block devices. If not specified it defaults to |
| the zone size. If the target device is a zoned block device, the zone |
| capacity is obtained from the device information and this option is |
| ignored. |
| |
| .. option:: zoneskip=int |
| |
| For :option:`zonemode` =strided, the number of bytes to skip after |
| :option:`zonesize` bytes of data have been transferred. This parameter |
| must be zero for :option:`zonemode` =zbd. |
| |
| .. option:: read_beyond_wp=bool |
| |
| This parameter applies to :option:`zonemode` =zbd only. |
| |
| Zoned block devices are block devices that consist of multiple zones. |
| Each zone has a type, e.g. conventional or sequential. A conventional |
| zone can be written at any offset that is a multiple of the block |
| size. Sequential zones must be written sequentially. The position at |
| which a write must occur is called the write pointer. A zoned block |
| device can be either drive managed, host managed or host aware. For |
| host managed devices the host must ensure that writes happen |
| sequentially. Fio recognizes host managed devices and serializes |
| writes to sequential zones for these devices. |
| |
| If a read occurs in a sequential zone beyond the write pointer then |
| the zoned block device will complete the read without reading any data |
| from the storage medium. Since such reads lead to unrealistically high |
| bandwidth and IOPS numbers fio only reads beyond the write pointer if |
| explicitly told to do so. Default: false. |
| |
| .. option:: max_open_zones=int |
| |
| When running a random write test across an entire drive many more |
| zones will be open than in a typical application workload. Hence this |
| command line option that allows to limit the number of open zones. The |
| number of open zones is defined as the number of zones to which write |
| commands are issued. |
| |
| .. option:: zone_reset_threshold=float |
| |
| A number between zero and one that indicates the ratio of logical |
| blocks with data to the total number of logical blocks in the test |
| above which zones should be reset periodically. |
| |
| .. option:: zone_reset_frequency=float |
| |
| A number between zero and one that indicates how often a zone reset |
| should be issued if the zone reset threshold has been exceeded. A zone |
| reset is submitted after each (1 / zone_reset_frequency) write |
| requests. This and the previous parameter can be used to simulate |
| garbage collection activity. |
| |
| |
| I/O type |
| ~~~~~~~~ |
| |
| .. option:: direct=bool |
| |
| If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that |
| OpenBSD and ZFS on Solaris don't support direct I/O. On Windows the synchronous |
| ioengines don't support direct I/O. Default: false. |
| |
| .. option:: atomic=bool |
| |
| If value is true, attempt to use atomic direct I/O. Atomic writes are |
| guaranteed to be stable once acknowledged by the operating system. Only |
| Linux supports O_ATOMIC right now. |
| |
| .. option:: buffered=bool |
| |
| If value is true, use buffered I/O. This is the opposite of the |
| :option:`direct` option. Defaults to true. |
| |
| .. option:: readwrite=str, rw=str |
| |
| Type of I/O pattern. Accepted values are: |
| |
| **read** |
| Sequential reads. |
| **write** |
| Sequential writes. |
| **trim** |
| Sequential trims (Linux block devices and SCSI |
| character devices only). |
| **randread** |
| Random reads. |
| **randwrite** |
| Random writes. |
| **randtrim** |
| Random trims (Linux block devices and SCSI |
| character devices only). |
| **rw,readwrite** |
| Sequential mixed reads and writes. |
| **randrw** |
| Random mixed reads and writes. |
| **trimwrite** |
| Sequential trim+write sequences. Blocks will be trimmed first, |
| then the same blocks will be written to. |
| |
| Fio defaults to read if the option is not specified. For the mixed I/O |
| types, the default is to split them 50/50. For certain types of I/O the |
| result may still be skewed a bit, since the speed may be different. |
| |
| It is possible to specify the number of I/Os to do before getting a new |
| offset by appending ``:<nr>`` to the end of the string given. For a |
| random read, it would look like ``rw=randread:8`` for passing in an offset |
| modifier with a value of 8. If the suffix is used with a sequential I/O |
| pattern, then the *<nr>* value specified will be **added** to the generated |
| offset for each I/O turning sequential I/O into sequential I/O with holes. |
| For instance, using ``rw=write:4k`` will skip 4k for every write. Also see |
| the :option:`rw_sequencer` option. |
| |
| .. option:: rw_sequencer=str |
| |
| If an offset modifier is given by appending a number to the ``rw=<str>`` |
| line, then this option controls how that number modifies the I/O offset |
| being generated. Accepted values are: |
| |
| **sequential** |
| Generate sequential offset. |
| **identical** |
| Generate the same offset. |
| |
| ``sequential`` is only useful for random I/O, where fio would normally |
| generate a new random offset for every I/O. If you append e.g. 8 to randread, |
| you would get a new random offset for every 8 I/Os. The result would be a |
| seek for only every 8 I/Os, instead of for every I/O. Use ``rw=randread:8`` |
| to specify that. As sequential I/O is already sequential, setting |
| ``sequential`` for that would not result in any differences. ``identical`` |
| behaves in a similar fashion, except it sends the same offset 8 number of |
| times before generating a new offset. |
| |
| .. option:: unified_rw_reporting=str |
| |
| Fio normally reports statistics on a per data direction basis, meaning that |
| reads, writes, and trims are accounted and reported separately. This option |
| determines whether fio reports the results normally, summed together, or as |
| both options. |
| Accepted values are: |
| |
| **none** |
| Normal statistics reporting. |
| |
| **mixed** |
| Statistics are summed per data direction and reported together. |
| |
| **both** |
| Statistics are reported normally, followed by the mixed statistics. |
| |
| **0** |
| Backward-compatible alias for **none**. |
| |
| **1** |
| Backward-compatible alias for **mixed**. |
| |
| **2** |
| Alias for **both**. |
| |
| .. option:: randrepeat=bool |
| |
| Seed the random number generator used for random I/O patterns in a |
| predictable way so the pattern is repeatable across runs. Default: true. |
| |
| .. option:: allrandrepeat=bool |
| |
| Seed all random number generators in a predictable way so results are |
| repeatable across runs. Default: false. |
| |
| .. option:: randseed=int |
| |
| Seed the random number generators based on this seed value, to be able to |
| control what sequence of output is being generated. If not set, the random |
| sequence depends on the :option:`randrepeat` setting. |
| |
| .. option:: fallocate=str |
| |
| Whether pre-allocation is performed when laying down files. |
| Accepted values are: |
| |
| **none** |
| Do not pre-allocate space. |
| |
| **native** |
| Use a platform's native pre-allocation call but fall back to |
| **none** behavior if it fails/is not implemented. |
| |
| **posix** |
| Pre-allocate via :manpage:`posix_fallocate(3)`. |
| |
| **keep** |
| Pre-allocate via :manpage:`fallocate(2)` with |
| FALLOC_FL_KEEP_SIZE set. |
| |
| **truncate** |
| Extend file to final size via :manpage:`ftruncate(2)` |
| instead of allocating. |
| |
| **0** |
| Backward-compatible alias for **none**. |
| |
| **1** |
| Backward-compatible alias for **posix**. |
| |
| May not be available on all supported platforms. **keep** is only available |
| on Linux. If using ZFS on Solaris this cannot be set to **posix** |
| because ZFS doesn't support pre-allocation. Default: **native** if any |
| pre-allocation methods except **truncate** are available, **none** if not. |
| |
| Note that using **truncate** on Windows will interact surprisingly |
| with non-sequential write patterns. When writing to a file that has |
| been extended by setting the end-of-file information, Windows will |
| backfill the unwritten portion of the file up to that offset with |
| zeroes before issuing the new write. This means that a single small |
| write to the end of an extended file will stall until the entire |
| file has been filled with zeroes. |
| |
| .. option:: fadvise_hint=str |
| |
| Use :manpage:`posix_fadvise(2)` or :manpage:`posix_fadvise(2)` to |
| advise the kernel on what I/O patterns are likely to be issued. |
| Accepted values are: |
| |
| **0** |
| Backwards-compatible hint for "no hint". |
| |
| **1** |
| Backwards compatible hint for "advise with fio workload type". This |
| uses **FADV_RANDOM** for a random workload, and **FADV_SEQUENTIAL** |
| for a sequential workload. |
| |
| **sequential** |
| Advise using **FADV_SEQUENTIAL**. |
| |
| **random** |
| Advise using **FADV_RANDOM**. |
| |
| .. option:: write_hint=str |
| |
| Use :manpage:`fcntl(2)` to advise the kernel what life time to expect |
| from a write. Only supported on Linux, as of version 4.13. Accepted |
| values are: |
| |
| **none** |
| No particular life time associated with this file. |
| |
| **short** |
| Data written to this file has a short life time. |
| |
| **medium** |
| Data written to this file has a medium life time. |
| |
| **long** |
| Data written to this file has a long life time. |
| |
| **extreme** |
| Data written to this file has a very long life time. |
| |
| The values are all relative to each other, and no absolute meaning |
| should be associated with them. |
| |
| .. option:: offset=int |
| |
| Start I/O at the provided offset in the file, given as either a fixed size in |
| bytes or a percentage. If a percentage is given, the generated offset will be |
| aligned to the minimum ``blocksize`` or to the value of ``offset_align`` if |
| provided. Data before the given offset will not be touched. This |
| effectively caps the file size at `real_size - offset`. Can be combined with |
| :option:`size` to constrain the start and end range of the I/O workload. |
| A percentage can be specified by a number between 1 and 100 followed by '%', |
| for example, ``offset=20%`` to specify 20%. |
| |
| .. option:: offset_align=int |
| |
| If set to non-zero value, the byte offset generated by a percentage ``offset`` |
| is aligned upwards to this value. Defaults to 0 meaning that a percentage |
| offset is aligned to the minimum block size. |
| |
| .. option:: offset_increment=int |
| |
| If this is provided, then the real offset becomes `offset + offset_increment |
| * thread_number`, where the thread number is a counter that starts at 0 and |
| is incremented for each sub-job (i.e. when :option:`numjobs` option is |
| specified). This option is useful if there are several jobs which are |
| intended to operate on a file in parallel disjoint segments, with even |
| spacing between the starting points. Percentages can be used for this option. |
| If a percentage is given, the generated offset will be aligned to the minimum |
| ``blocksize`` or to the value of ``offset_align`` if provided. |
| |
| .. option:: number_ios=int |
| |
| Fio will normally perform I/Os until it has exhausted the size of the region |
| set by :option:`size`, or if it exhaust the allocated time (or hits an error |
| condition). With this setting, the range/size can be set independently of |
| the number of I/Os to perform. When fio reaches this number, it will exit |
| normally and report status. Note that this does not extend the amount of I/O |
| that will be done, it will only stop fio if this condition is met before |
| other end-of-job criteria. |
| |
| .. option:: fsync=int |
| |
| If writing to a file, issue an :manpage:`fsync(2)` (or its equivalent) of |
| the dirty data for every number of blocks given. For example, if you give 32 |
| as a parameter, fio will sync the file after every 32 writes issued. If fio is |
| using non-buffered I/O, we may not sync the file. The exception is the sg |
| I/O engine, which synchronizes the disk cache anyway. Defaults to 0, which |
| means fio does not periodically issue and wait for a sync to complete. Also |
| see :option:`end_fsync` and :option:`fsync_on_close`. |
| |
| .. option:: fdatasync=int |
| |
| Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and |
| not metadata blocks. In Windows, FreeBSD, DragonFlyBSD or OSX there is no |
| :manpage:`fdatasync(2)` so this falls back to using :manpage:`fsync(2)`. |
| Defaults to 0, which means fio does not periodically issue and wait for a |
| data-only sync to complete. |
| |
| .. option:: write_barrier=int |
| |
| Make every `N-th` write a barrier write. |
| |
| .. option:: sync_file_range=str:int |
| |
| Use :manpage:`sync_file_range(2)` for every `int` number of write |
| operations. Fio will track range of writes that have happened since the last |
| :manpage:`sync_file_range(2)` call. `str` can currently be one or more of: |
| |
| **wait_before** |
| SYNC_FILE_RANGE_WAIT_BEFORE |
| **write** |
| SYNC_FILE_RANGE_WRITE |
| **wait_after** |
| SYNC_FILE_RANGE_WAIT_AFTER |
| |
| So if you do ``sync_file_range=wait_before,write:8``, fio would use |
| ``SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE`` for every 8 |
| writes. Also see the :manpage:`sync_file_range(2)` man page. This option is |
| Linux specific. |
| |
| .. option:: overwrite=bool |
| |
| If true, writes to a file will always overwrite existing data. If the file |
| doesn't already exist, it will be created before the write phase begins. If |
| the file exists and is large enough for the specified write phase, nothing |
| will be done. Default: false. |
| |
| .. option:: end_fsync=bool |
| |
| If true, :manpage:`fsync(2)` file contents when a write stage has completed. |
| Default: false. |
| |
| .. option:: fsync_on_close=bool |
| |
| If true, fio will :manpage:`fsync(2)` a dirty file on close. This differs |
| from :option:`end_fsync` in that it will happen on every file close, not |
| just at the end of the job. Default: false. |
| |
| .. option:: rwmixread=int |
| |
| Percentage of a mixed workload that should be reads. Default: 50. |
| |
| .. option:: rwmixwrite=int |
| |
| Percentage of a mixed workload that should be writes. If both |
| :option:`rwmixread` and :option:`rwmixwrite` is given and the values do not |
| add up to 100%, the latter of the two will be used to override the |
| first. This may interfere with a given rate setting, if fio is asked to |
| limit reads or writes to a certain rate. If that is the case, then the |
| distribution may be skewed. Default: 50. |
| |
| .. option:: random_distribution=str:float[:float][,str:float][,str:float] |
| |
| By default, fio will use a completely uniform random distribution when asked |
| to perform random I/O. Sometimes it is useful to skew the distribution in |
| specific ways, ensuring that some parts of the data is more hot than others. |
| fio includes the following distribution models: |
| |
| **random** |
| Uniform random distribution |
| |
| **zipf** |
| Zipf distribution |
| |
| **pareto** |
| Pareto distribution |
| |
| **normal** |
| Normal (Gaussian) distribution |
| |
| **zoned** |
| Zoned random distribution |
| |
| **zoned_abs** |
| Zone absolute random distribution |
| |
| When using a **zipf** or **pareto** distribution, an input value is also |
| needed to define the access pattern. For **zipf**, this is the `Zipf |
| theta`. For **pareto**, it's the `Pareto power`. Fio includes a test |
| program, :command:`fio-genzipf`, that can be used visualize what the given input |
| values will yield in terms of hit rates. If you wanted to use **zipf** with |
| a `theta` of 1.2, you would use ``random_distribution=zipf:1.2`` as the |
| option. If a non-uniform model is used, fio will disable use of the random |
| map. For the **normal** distribution, a normal (Gaussian) deviation is |
| supplied as a value between 0 and 100. |
| |
| The second, optional float is allowed for **pareto**, **zipf** and **normal** distributions. |
| It allows to set base of distribution in non-default place, giving more control |
| over most probable outcome. This value is in range [0-1] which maps linearly to |
| range of possible random values. |
| Defaults are: random for **pareto** and **zipf**, and 0.5 for **normal**. |
| If you wanted to use **zipf** with a `theta` of 1.2 centered on 1/4 of allowed value range, |
| you would use ``random_distibution=zipf:1.2:0.25``. |
| |
| For a **zoned** distribution, fio supports specifying percentages of I/O |
| access that should fall within what range of the file or device. For |
| example, given a criteria of: |
| |
| * 60% of accesses should be to the first 10% |
| * 30% of accesses should be to the next 20% |
| * 8% of accesses should be to the next 30% |
| * 2% of accesses should be to the next 40% |
| |
| we can define that through zoning of the random accesses. For the above |
| example, the user would do:: |
| |
| random_distribution=zoned:60/10:30/20:8/30:2/40 |
| |
| A **zoned_abs** distribution works exactly like the **zoned**, except |
| that it takes absolute sizes. For example, let's say you wanted to |
| define access according to the following criteria: |
| |
| * 60% of accesses should be to the first 20G |
| * 30% of accesses should be to the next 100G |
| * 10% of accesses should be to the next 500G |
| |
| we can define an absolute zoning distribution with: |
| |
| random_distribution=zoned_abs=60/20G:30/100G:10/500g |
| |
| For both **zoned** and **zoned_abs**, fio supports defining up to |
| 256 separate zones. |
| |
| Similarly to how :option:`bssplit` works for setting ranges and |
| percentages of block sizes. Like :option:`bssplit`, it's possible to |
| specify separate zones for reads, writes, and trims. If just one set |
| is given, it'll apply to all of them. This goes for both **zoned** |
| **zoned_abs** distributions. |
| |
| .. option:: percentage_random=int[,int][,int] |
| |
| For a random workload, set how big a percentage should be random. This |
| defaults to 100%, in which case the workload is fully random. It can be set |
| from anywhere from 0 to 100. Setting it to 0 would make the workload fully |
| sequential. Any setting in between will result in a random mix of sequential |
| and random I/O, at the given percentages. Comma-separated values may be |
| specified for reads, writes, and trims as described in :option:`blocksize`. |
| |
| .. option:: norandommap |
| |
| Normally fio will cover every block of the file when doing random I/O. If |
| this option is given, fio will just get a new random offset without looking |
| at past I/O history. This means that some blocks may not be read or written, |
| and that some blocks may be read/written more than once. If this option is |
| used with :option:`verify` and multiple blocksizes (via :option:`bsrange`), |
| only intact blocks are verified, i.e., partially-overwritten blocks are |
| ignored. With an async I/O engine and an I/O depth > 1, it is possible for |
| the same block to be overwritten, which can cause verification errors. Either |
| do not use norandommap in this case, or also use the lfsr random generator. |
| |
| .. option:: softrandommap=bool |
| |
| See :option:`norandommap`. If fio runs with the random block map enabled and |
| it fails to allocate the map, if this option is set it will continue without |
| a random block map. As coverage will not be as complete as with random maps, |
| this option is disabled by default. |
| |
| .. option:: random_generator=str |
| |
| Fio supports the following engines for generating I/O offsets for random I/O: |
| |
| **tausworthe** |
| Strong 2^88 cycle random number generator. |
| **lfsr** |
| Linear feedback shift register generator. |
| **tausworthe64** |
| Strong 64-bit 2^258 cycle random number generator. |
| |
| **tausworthe** is a strong random number generator, but it requires tracking |
| on the side if we want to ensure that blocks are only read or written |
| once. **lfsr** guarantees that we never generate the same offset twice, and |
| it's also less computationally expensive. It's not a true random generator, |
| however, though for I/O purposes it's typically good enough. **lfsr** only |
| works with single block sizes, not with workloads that use multiple block |
| sizes. If used with such a workload, fio may read or write some blocks |
| multiple times. The default value is **tausworthe**, unless the required |
| space exceeds 2^32 blocks. If it does, then **tausworthe64** is |
| selected automatically. |
| |
| |
| Block size |
| ~~~~~~~~~~ |
| |
| .. option:: blocksize=int[,int][,int], bs=int[,int][,int] |
| |
| The block size in bytes used for I/O units. Default: 4096. A single value |
| applies to reads, writes, and trims. Comma-separated values may be |
| specified for reads, writes, and trims. A value not terminated in a comma |
| applies to subsequent types. |
| |
| Examples: |
| |
| **bs=256k** |
| means 256k for reads, writes and trims. |
| |
| **bs=8k,32k** |
| means 8k for reads, 32k for writes and trims. |
| |
| **bs=8k,32k,** |
| means 8k for reads, 32k for writes, and default for trims. |
| |
| **bs=,8k** |
| means default for reads, 8k for writes and trims. |
| |
| **bs=,8k,** |
| means default for reads, 8k for writes, and default for trims. |
| |
| .. option:: blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange] |
| |
| A range of block sizes in bytes for I/O units. The issued I/O unit will |
| always be a multiple of the minimum size, unless |
| :option:`blocksize_unaligned` is set. |
| |
| Comma-separated ranges may be specified for reads, writes, and trims as |
| described in :option:`blocksize`. |
| |
| Example: ``bsrange=1k-4k,2k-8k``. |
| |
| .. option:: bssplit=str[,str][,str] |
| |
| Sometimes you want even finer grained control of the block sizes |
| issued, not just an even split between them. This option allows you to |
| weight various block sizes, so that you are able to define a specific |
| amount of block sizes issued. The format for this option is:: |
| |
| bssplit=blocksize/percentage:blocksize/percentage |
| |
| for as many block sizes as needed. So if you want to define a workload |
| that has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would |
| write:: |
| |
| bssplit=4k/10:64k/50:32k/40 |
| |
| Ordering does not matter. If the percentage is left blank, fio will |
| fill in the remaining values evenly. So a bssplit option like this one:: |
| |
| bssplit=4k/50:1k/:32k/ |
| |
| would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always |
| add up to 100, if bssplit is given a range that adds up to more, it |
| will error out. |
| |
| Comma-separated values may be specified for reads, writes, and trims as |
| described in :option:`blocksize`. |
| |
| If you want a workload that has 50% 2k reads and 50% 4k reads, while |
| having 90% 4k writes and 10% 8k writes, you would specify:: |
| |
| bssplit=2k/50:4k/50,4k/90:8k/10 |
| |
| Fio supports defining up to 64 different weights for each data |
| direction. |
| |
| .. option:: blocksize_unaligned, bs_unaligned |
| |
| If set, fio will issue I/O units with any size within |
| :option:`blocksize_range`, not just multiples of the minimum size. This |
| typically won't work with direct I/O, as that normally requires sector |
| alignment. |
| |
| .. option:: bs_is_seq_rand=bool |
| |
| If this option is set, fio will use the normal read,write blocksize settings |
| as sequential,random blocksize settings instead. Any random read or write |
| will use the WRITE blocksize settings, and any sequential read or write will |
| use the READ blocksize settings. |
| |
| .. option:: blockalign=int[,int][,int], ba=int[,int][,int] |
| |
| Boundary to which fio will align random I/O units. Default: |
| :option:`blocksize`. Minimum alignment is typically 512b for using direct |
| I/O, though it usually depends on the hardware block size. This option is |
| mutually exclusive with using a random map for files, so it will turn off |
| that option. Comma-separated values may be specified for reads, writes, and |
| trims as described in :option:`blocksize`. |
| |
| |
| Buffers and memory |
| ~~~~~~~~~~~~~~~~~~ |
| |
| .. option:: zero_buffers |
| |
| Initialize buffers with all zeros. Default: fill buffers with random data. |
| |
| .. option:: refill_buffers |
| |
| If this option is given, fio will refill the I/O buffers on every |
| submit. Only makes sense if :option:`zero_buffers` isn't specified, |
| naturally. Defaults to being unset i.e., the buffer is only filled at |
| init time and the data in it is reused when possible but if any of |
| :option:`verify`, :option:`buffer_compress_percentage` or |
| :option:`dedupe_percentage` are enabled then `refill_buffers` is also |
| automatically enabled. |
| |
| .. option:: scramble_buffers=bool |
| |
| If :option:`refill_buffers` is too costly and the target is using data |
| deduplication, then setting this option will slightly modify the I/O buffer |
| contents to defeat normal de-dupe attempts. This is not enough to defeat |
| more clever block compression attempts, but it will stop naive dedupe of |
| blocks. Default: true. |
| |
| .. option:: buffer_compress_percentage=int |
| |
| If this is set, then fio will attempt to provide I/O buffer content |
| (on WRITEs) that compresses to the specified level. Fio does this by |
| providing a mix of random data followed by fixed pattern data. The |
| fixed pattern is either zeros, or the pattern specified by |
| :option:`buffer_pattern`. If the `buffer_pattern` option is used, it |
| might skew the compression ratio slightly. Setting |
| `buffer_compress_percentage` to a value other than 100 will also |
| enable :option:`refill_buffers` in order to reduce the likelihood that |
| adjacent blocks are so similar that they over compress when seen |
| together. See :option:`buffer_compress_chunk` for how to set a finer or |
| coarser granularity for the random/fixed data region. Defaults to unset |
| i.e., buffer data will not adhere to any compression level. |
| |
| .. option:: buffer_compress_chunk=int |
| |
| This setting allows fio to manage how big the random/fixed data region |
| is when using :option:`buffer_compress_percentage`. When |
| `buffer_compress_chunk` is set to some non-zero value smaller than the |
| block size, fio can repeat the random/fixed region throughout the I/O |
| buffer at the specified interval (which particularly useful when |
| bigger block sizes are used for a job). When set to 0, fio will use a |
| chunk size that matches the block size resulting in a single |
| random/fixed region within the I/O buffer. Defaults to 512. When the |
| unit is omitted, the value is interpreted in bytes. |
| |
| .. option:: buffer_pattern=str |
| |
| If set, fio will fill the I/O buffers with this pattern or with the contents |
| of a file. If not set, the contents of I/O buffers are defined by the other |
| options related to buffer contents. The setting can be any pattern of bytes, |
| and can be prefixed with 0x for hex values. It may also be a string, where |
| the string must then be wrapped with ``""``. Or it may also be a filename, |
| where the filename must be wrapped with ``''`` in which case the file is |
| opened and read. Note that not all the file contents will be read if that |
| would cause the buffers to overflow. So, for example:: |
| |
| buffer_pattern='filename' |
| |
| or:: |
| |
| buffer_pattern="abcd" |
| |
| or:: |
| |
| buffer_pattern=-12 |
| |
| or:: |
| |
| buffer_pattern=0xdeadface |
| |
| Also you can combine everything together in any order:: |
| |
| buffer_pattern=0xdeadface"abcd"-12'filename' |
| |
| .. option:: dedupe_percentage=int |
| |
| If set, fio will generate this percentage of identical buffers when |
| writing. These buffers will be naturally dedupable. The contents of the |
| buffers depend on what other buffer compression settings have been set. It's |
| possible to have the individual buffers either fully compressible, or not at |
| all -- this option only controls the distribution of unique buffers. Setting |
| this option will also enable :option:`refill_buffers` to prevent every buffer |
| being identical. |
| |
| .. option:: invalidate=bool |
| |
| Invalidate the buffer/page cache parts of the files to be used prior to |
| starting I/O if the platform and file type support it. Defaults to true. |
| This will be ignored if :option:`pre_read` is also specified for the |
| same job. |
| |
| .. option:: sync=str |
| |
| Whether, and what type, of synchronous I/O to use for writes. The allowed |
| values are: |
| |
| **none** |
| Do not use synchronous IO, the default. |
| |
| **0** |
| Same as **none**. |
| |
| **sync** |
| Use synchronous file IO. For the majority of I/O engines, |
| this means using O_SYNC. |
| |
| **1** |
| Same as **sync**. |
| |
| **dsync** |
| Use synchronous data IO. For the majority of I/O engines, |
| this means using O_DSYNC. |
| |
| |
| .. option:: iomem=str, mem=str |
| |
| Fio can use various types of memory as the I/O unit buffer. The allowed |
| values are: |
| |
| **malloc** |
| Use memory from :manpage:`malloc(3)` as the buffers. Default memory |
| type. |
| |
| **shm** |
| Use shared memory as the buffers. Allocated through |
| :manpage:`shmget(2)`. |
| |
| **shmhuge** |
| Same as shm, but use huge pages as backing. |
| |
| **mmap** |
| Use :manpage:`mmap(2)` to allocate buffers. May either be anonymous memory, or can |
| be file backed if a filename is given after the option. The format |
| is `mem=mmap:/path/to/file`. |
| |
| **mmaphuge** |
| Use a memory mapped huge file as the buffer backing. Append filename |
| after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file`. |
| |
| **mmapshared** |
| Same as mmap, but use a MMAP_SHARED mapping. |
| |
| **cudamalloc** |
| Use GPU memory as the buffers for GPUDirect RDMA benchmark. |
| The :option:`ioengine` must be `rdma`. |
| |
| The area allocated is a function of the maximum allowed bs size for the job, |
| multiplied by the I/O depth given. Note that for **shmhuge** and |
| **mmaphuge** to work, the system must have free huge pages allocated. This |
| can normally be checked and set by reading/writing |
| :file:`/proc/sys/vm/nr_hugepages` on a Linux system. Fio assumes a huge page |
| is 4MiB in size. So to calculate the number of huge pages you need for a |
| given job file, add up the I/O depth of all jobs (normally one unless |
| :option:`iodepth` is used) and multiply by the maximum bs set. Then divide |
| that number by the huge page size. You can see the size of the huge pages in |
| :file:`/proc/meminfo`. If no huge pages are allocated by having a non-zero |
| number in `nr_hugepages`, using **mmaphuge** or **shmhuge** will fail. Also |
| see :option:`hugepage-size`. |
| |
| **mmaphuge** also needs to have hugetlbfs mounted and the file location |
| should point there. So if it's mounted in :file:`/huge`, you would use |
| `mem=mmaphuge:/huge/somefile`. |
| |
| .. option:: iomem_align=int, mem_align=int |
| |
| This indicates the memory alignment of the I/O memory buffers. Note that |
| the given alignment is applied to the first I/O unit buffer, if using |
| :option:`iodepth` the alignment of the following buffers are given by the |
| :option:`bs` used. In other words, if using a :option:`bs` that is a |
| multiple of the page sized in the system, all buffers will be aligned to |
| this value. If using a :option:`bs` that is not page aligned, the alignment |
| of subsequent I/O memory buffers is the sum of the :option:`iomem_align` and |
| :option:`bs` used. |
| |
| .. option:: hugepage-size=int |
| |
| Defines the size of a huge page. Must at least be equal to the system |
| setting, see :file:`/proc/meminfo`. Defaults to 4MiB. Should probably |
| always be a multiple of megabytes, so using ``hugepage-size=Xm`` is the |
| preferred way to set this to avoid setting a non-pow-2 bad value. |
| |
| .. option:: lockmem=int |
| |
| Pin the specified amount of memory with :manpage:`mlock(2)`. Can be used to |
| simulate a smaller amount of memory. The amount specified is per worker. |
| |
| |
| I/O size |
| ~~~~~~~~ |
| |
| .. option:: size=int |
| |
| The total size of file I/O for each thread of this job. Fio will run until |
| this many bytes has been transferred, unless runtime is limited by other options |
| (such as :option:`runtime`, for instance, or increased/decreased by :option:`io_size`). |
| Fio will divide this size between the available files determined by options |
| such as :option:`nrfiles`, :option:`filename`, unless :option:`filesize` is |
| specified by the job. If the result of division happens to be 0, the size is |
| set to the physical size of the given files or devices if they exist. |
| If this option is not specified, fio will use the full size of the given |
| files or devices. If the files do not exist, size must be given. It is also |
| possible to give size as a percentage between 1 and 100. If ``size=20%`` is |
| given, fio will use 20% of the full size of the given files or devices. |
| Can be combined with :option:`offset` to constrain the start and end range |
| that I/O will be done within. |
| |
| .. option:: io_size=int, io_limit=int |
| |
| Normally fio operates within the region set by :option:`size`, which means |
| that the :option:`size` option sets both the region and size of I/O to be |
| performed. Sometimes that is not what you want. With this option, it is |
| possible to define just the amount of I/O that fio should do. For instance, |
| if :option:`size` is set to 20GiB and :option:`io_size` is set to 5GiB, fio |
| will perform I/O within the first 20GiB but exit when 5GiB have been |
| done. The opposite is also possible -- if :option:`size` is set to 20GiB, |
| and :option:`io_size` is set to 40GiB, then fio will do 40GiB of I/O within |
| the 0..20GiB region. |
| |
| .. option:: filesize=irange(int) |
| |
| Individual file sizes. May be a range, in which case fio will select sizes |
| for files at random within the given range and limited to :option:`size` in |
| total (if that is given). If not given, each created file is the same size. |
| This option overrides :option:`size` in terms of file size, which means |
| this value is used as a fixed size or possible range of each file. |
| |
| .. option:: file_append=bool |
| |
| Perform I/O after the end of the file. Normally fio will operate within the |
| size of a file. If this option is set, then fio will append to the file |
| instead. This has identical behavior to setting :option:`offset` to the size |
| of a file. This option is ignored on non-regular files. |
| |
| .. option:: fill_device=bool, fill_fs=bool |
| |
| Sets size to something really large and waits for ENOSPC (no space left on |
| device) as the terminating condition. Only makes sense with sequential |
| write. For a read workload, the mount point will be filled first then I/O |
| started on the result. This option doesn't make sense if operating on a raw |
| device node, since the size of that is already known by the file system. |
| Additionally, writing beyond end-of-device will not return ENOSPC there. |
| |
| |
| I/O engine |
| ~~~~~~~~~~ |
| |
| .. option:: ioengine=str |
| |
| Defines how the job issues I/O to the file. The following types are defined: |
| |
| **sync** |
| Basic :manpage:`read(2)` or :manpage:`write(2)` |
| I/O. :manpage:`lseek(2)` is used to position the I/O location. |
| See :option:`fsync` and :option:`fdatasync` for syncing write I/Os. |
| |
| **psync** |
| Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O. Default on |
| all supported operating systems except for Windows. |
| |
| **vsync** |
| Basic :manpage:`readv(2)` or :manpage:`writev(2)` I/O. Will emulate |
| queuing by coalescing adjacent I/Os into a single submission. |
| |
| **pvsync** |
| Basic :manpage:`preadv(2)` or :manpage:`pwritev(2)` I/O. |
| |
| **pvsync2** |
| Basic :manpage:`preadv2(2)` or :manpage:`pwritev2(2)` I/O. |
| |
| **io_uring** |
| Fast Linux native asynchronous I/O. Supports async IO |
| for both direct and buffered IO. |
| This engine defines engine specific options. |
| |
| **libaio** |
| Linux native asynchronous I/O. Note that Linux may only support |
| queued behavior with non-buffered I/O (set ``direct=1`` or |
| ``buffered=0``). |
| This engine defines engine specific options. |
| |
| **posixaio** |
| POSIX asynchronous I/O using :manpage:`aio_read(3)` and |
| :manpage:`aio_write(3)`. |
| |
| **solarisaio** |
| Solaris native asynchronous I/O. |
| |
| **windowsaio** |
| Windows native asynchronous I/O. Default on Windows. |
| |
| **mmap** |
| File is memory mapped with :manpage:`mmap(2)` and data copied |
| to/from using :manpage:`memcpy(3)`. |
| |
| **splice** |
| :manpage:`splice(2)` is used to transfer the data and |
| :manpage:`vmsplice(2)` to transfer data from user space to the |
| kernel. |
| |
| **sg** |
| SCSI generic sg v3 I/O. May either be synchronous using the SG_IO |
| ioctl, or if the target is an sg character device we use |
| :manpage:`read(2)` and :manpage:`write(2)` for asynchronous |
| I/O. Requires :option:`filename` option to specify either block or |
| character devices. This engine supports trim operations. |
| The sg engine includes engine specific options. |
| |
| **null** |
| Doesn't transfer any data, just pretends to. This is mainly used to |
| exercise fio itself and for debugging/testing purposes. |
| |
| **net** |
| Transfer over the network to given ``host:port``. Depending on the |
| :option:`protocol` used, the :option:`hostname`, :option:`port`, |
| :option:`listen` and :option:`filename` options are used to specify |
| what sort of connection to make, while the :option:`protocol` option |
| determines which protocol will be used. This engine defines engine |
| specific options. |
| |
| **netsplice** |
| Like **net**, but uses :manpage:`splice(2)` and |
| :manpage:`vmsplice(2)` to map data and send/receive. |
| This engine defines engine specific options. |
| |
| **cpuio** |
| Doesn't transfer any data, but burns CPU cycles according to the |
| :option:`cpuload`, :option:`cpuchunks` and :option:`cpumode` options. |
| Setting :option:`cpuload`\=85 will cause that job to do nothing but burn 85% |
| of the CPU. In case of SMP machines, use :option:`numjobs`\=<nr_of_cpu> |
| to get desired CPU usage, as the cpuload only loads a |
| single CPU at the desired rate. A job never finishes unless there is |
| at least one non-cpuio job. |
| Setting :option:`cpumode`\=qsort replace the default noop instructions loop |
| by a qsort algorithm to consume more energy. |
| |
| **rdma** |
| The RDMA I/O engine supports both RDMA memory semantics |
| (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the |
| InfiniBand, RoCE and iWARP protocols. This engine defines engine |
| specific options. |
| |
| **falloc** |
| I/O engine that does regular fallocate to simulate data transfer as |
| fio ioengine. |
| |
| DDIR_READ |
| does fallocate(,mode = FALLOC_FL_KEEP_SIZE,). |
| |
| DDIR_WRITE |
| does fallocate(,mode = 0). |
| |
| DDIR_TRIM |
| does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE). |
| |
| **ftruncate** |
| I/O engine that sends :manpage:`ftruncate(2)` operations in response |
| to write (DDIR_WRITE) events. Each ftruncate issued sets the file's |
| size to the current block offset. :option:`blocksize` is ignored. |
| |
| **e4defrag** |
| I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate |
| defragment activity in request to DDIR_WRITE event. |
| |
| **rados** |
| I/O engine supporting direct access to Ceph Reliable Autonomic |
| Distributed Object Store (RADOS) via librados. This ioengine |
| defines engine specific options. |
| |
| **rbd** |
| I/O engine supporting direct access to Ceph Rados Block Devices |
| (RBD) via librbd without the need to use the kernel rbd driver. This |
| ioengine defines engine specific options. |
| |
| **http** |
| I/O engine supporting GET/PUT requests over HTTP(S) with libcurl to |
| a WebDAV or S3 endpoint. This ioengine defines engine specific options. |
| |
| This engine only supports direct IO of iodepth=1; you need to scale this |
| via numjobs. blocksize defines the size of the objects to be created. |
| |
| TRIM is translated to object deletion. |
| |
| **gfapi** |
| Using GlusterFS libgfapi sync interface to direct access to |
| GlusterFS volumes without having to go through FUSE. This ioengine |
| defines engine specific options. |
| |
| **gfapi_async** |
| Using GlusterFS libgfapi async interface to direct access to |
| GlusterFS volumes without having to go through FUSE. This ioengine |
| defines engine specific options. |
| |
| **libhdfs** |
| Read and write through Hadoop (HDFS). The :option:`filename` option |
| is used to specify host,port of the hdfs name-node to connect. This |
| engine interprets offsets a little differently. In HDFS, files once |
| created cannot be modified so random writes are not possible. To |
| imitate this the libhdfs engine expects a bunch of small files to be |
| created over HDFS and will randomly pick a file from them |
| based on the offset generated by fio backend (see the example |
| job file to create such files, use ``rw=write`` option). Please |
| note, it may be necessary to set environment variables to work |
| with HDFS/libhdfs properly. Each job uses its own connection to |
| HDFS. |
| |
| **mtd** |
| Read, write and erase an MTD character device (e.g., |
| :file:`/dev/mtd0`). Discards are treated as erases. Depending on the |
| underlying device type, the I/O may have to go in a certain pattern, |
| e.g., on NAND, writing sequentially to erase blocks and discarding |
| before overwriting. The `trimwrite` mode works well for this |
| constraint. |
| |
| **pmemblk** |
| Read and write using filesystem DAX to a file on a filesystem |
| mounted with DAX on a persistent memory device through the PMDK |
| libpmemblk library. |
| |
| **dev-dax** |
| Read and write using device DAX to a persistent memory device (e.g., |
| /dev/dax0.0) through the PMDK libpmem library. |
| |
| **external** |
| Prefix to specify loading an external I/O engine object file. Append |
| the engine filename, e.g. ``ioengine=external:/tmp/foo.o`` to load |
| ioengine :file:`foo.o` in :file:`/tmp`. The path can be either |
| absolute or relative. See :file:`engines/skeleton_external.c` for |
| details of writing an external I/O engine. |
| |
| **filecreate** |
| Simply create the files and do no I/O to them. You still need to |
| set `filesize` so that all the accounting still occurs, but no |
| actual I/O will be done other than creating the file. |
| |
| **filestat** |
| Simply do stat() and do no I/O to the file. You need to set 'filesize' |
| and 'nrfiles', so that files will be created. |
| This engine is to measure file lookup and meta data access. |
| |
| **filedelete** |
| Simply delete the files by unlink() and do no I/O to them. You need to set 'filesize' |
| and 'nrfiles', so that the files will be created. |
| This engine is to measure file delete. |
| |
| **libpmem** |
| Read and write using mmap I/O to a file on a filesystem |
| mounted with DAX on a persistent memory device through the PMDK |
| libpmem library. |
| |
| **ime_psync** |
| Synchronous read and write using DDN's Infinite Memory Engine (IME). |
| This engine is very basic and issues calls to IME whenever an IO is |
| queued. |
| |
| **ime_psyncv** |
| Synchronous read and write using DDN's Infinite Memory Engine (IME). |
| This engine uses iovecs and will try to stack as much IOs as possible |
| (if the IOs are "contiguous" and the IO depth is not exceeded) |
| before issuing a call to IME. |
| |
| **ime_aio** |
| Asynchronous read and write using DDN's Infinite Memory Engine (IME). |
| This engine will try to stack as much IOs as possible by creating |
| requests for IME. FIO will then decide when to commit these requests. |
| **libiscsi** |
| Read and write iscsi lun with libiscsi. |
| **nbd** |
| Read and write a Network Block Device (NBD). |
| |
| **libcufile** |
| I/O engine supporting libcufile synchronous access to nvidia-fs and a |
| GPUDirect Storage-supported filesystem. This engine performs |
| I/O without transferring buffers between user-space and the kernel, |
| unless :option:`verify` is set or :option:`cuda_io` is `posix`. |
| :option:`iomem` must not be `cudamalloc`. This ioengine defines |
| engine specific options. |
| **dfs** |
| I/O engine supporting asynchronous read and write operations to the |
| DAOS File System (DFS) via libdfs. |
| |
| I/O engine specific parameters |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| In addition, there are some parameters which are only valid when a specific |
| :option:`ioengine` is in use. These are used identically to normal parameters, |
| with the caveat that when used on the command line, they must come after the |
| :option:`ioengine` that defines them is selected. |
| |
| .. option:: cmdprio_percentage=int : [io_uring] [libaio] |
| |
| Set the percentage of I/O that will be issued with higher priority by setting |
| the priority bit. Non-read I/O is likely unaffected by ``cmdprio_percentage``. |
| This option cannot be used with the `prio` or `prioclass` options. For this |
| option to set the priority bit properly, NCQ priority must be supported and |
| enabled and :option:`direct`\=1 option must be used. fio must also be run as |
| the root user. |
| |
| .. option:: fixedbufs : [io_uring] |
| |
| If fio is asked to do direct IO, then Linux will map pages for each |
| IO call, and release them when IO is done. If this option is set, the |
| pages are pre-mapped before IO is started. This eliminates the need to |
| map and release for each IO. This is more efficient, and reduces the |
| IO latency as well. |
| |
| .. option:: hipri : [io_uring] |
| |
| If this option is set, fio will attempt to use polled IO completions. |
| Normal IO completions generate interrupts to signal the completion of |
| IO, polled completions do not. Hence they are require active reaping |
| by the application. The benefits are more efficient IO for high IOPS |
| scenarios, and lower latencies for low queue depth IO. |
| |
| .. option:: registerfiles : [io_uring] |
| |
| With this option, fio registers the set of files being used with the |
| kernel. This avoids the overhead of managing file counts in the kernel, |
| making the submission and completion part more lightweight. Required |
| for the below :option:`sqthread_poll` option. |
| |
| .. option:: sqthread_poll : [io_uring] |
| |
| Normally fio will submit IO by issuing a system call to notify the |
| kernel of available items in the SQ ring. If this option is set, the |
| act of submitting IO will be done by a polling thread in the kernel. |
| This frees up cycles for fio, at the cost of using more CPU in the |
| system. |
| |
| .. option:: sqthread_poll_cpu : [io_uring] |
| |
| When :option:`sqthread_poll` is set, this option provides a way to |
| define which CPU should be used for the polling thread. |
| |
| .. option:: userspace_reap : [libaio] |
| |
| Normally, with the libaio engine in use, fio will use the |
| :manpage:`io_getevents(2)` system call to reap newly returned events. With |
| this flag turned on, the AIO ring will be read directly from user-space to |
| reap events. The reaping mode is only enabled when polling for a minimum of |
| 0 events (e.g. when :option:`iodepth_batch_complete` `=0`). |
| |
| .. option:: hipri : [pvsync2] |
| |
| Set RWF_HIPRI on I/O, indicating to the kernel that it's of higher priority |
| than normal. |
| |
| .. option:: hipri_percentage : [pvsync2] |
| |
| When hipri is set this determines the probability of a pvsync2 I/O being high |
| priority. The default is 100%. |
| |
| .. option:: nowait : [pvsync2] [libaio] [io_uring] |
| |
| By default if a request cannot be executed immediately (e.g. resource starvation, |
| waiting on locks) it is queued and the initiating process will be blocked until |
| the required resource becomes free. |
| |
| This option sets the RWF_NOWAIT flag (supported from the 4.14 Linux kernel) and |
| the call will return instantly with EAGAIN or a partial result rather than waiting. |
| |
| It is useful to also use ignore_error=EAGAIN when using this option. |
| |
| Note: glibc 2.27, 2.28 have a bug in syscall wrappers preadv2, pwritev2. |
| They return EOPNOTSUP instead of EAGAIN. |
| |
| For cached I/O, using this option usually means a request operates only with |
| cached data. Currently the RWF_NOWAIT flag does not supported for cached write. |
| |
| For direct I/O, requests will only succeed if cache invalidation isn't required, |
| file blocks are fully allocated and the disk request could be issued immediately. |
| |
| .. option:: cpuload=int : [cpuio] |
| |
| Attempt to use the specified percentage of CPU cycles. This is a mandatory |
| option when using cpuio I/O engine. |
| |
| .. option:: cpuchunks=int : [cpuio] |
| |
| Split the load into cycles of the given time. In microseconds. |
| |
| .. option:: exit_on_io_done=bool : [cpuio] |
| |
| Detect when I/O threads are done, then exit. |
| |
| .. option:: namenode=str : [libhdfs] |
| |
| The hostname or IP address of a HDFS cluster namenode to contact. |
| |
| .. option:: port=int |
| |
| [libhdfs] |
| |
| The listening port of the HFDS cluster namenode. |
| |
| [netsplice], [net] |
| |
| The TCP or UDP port to bind to or connect to. If this is used with |
| :option:`numjobs` to spawn multiple instances of the same job type, then |
| this will be the starting port number since fio will use a range of |
| ports. |
| |
| [rdma], [librpma_*] |
| |
| The port to use for RDMA-CM communication. This should be the same value |
| on the client and the server side. |
| |
| .. option:: hostname=str : [netsplice] [net] [rdma] |
| |
| The hostname or IP address to use for TCP, UDP or RDMA-CM based I/O. If the job |
| is a TCP listener or UDP reader, the hostname is not used and must be omitted |
| unless it is a valid UDP multicast address. |
| |
| .. option:: serverip=str : [librpma_*] |
| |
| The IP address to be used for RDMA-CM based I/O. |
| |
| .. option:: direct_write_to_pmem=bool : [librpma_*] |
| |
| Set to 1 only when Direct Write to PMem from the remote host is possible. |
| Otherwise, set to 0. |
| |
| .. option:: interface=str : [netsplice] [net] |
| |
| The IP address of the network interface used to send or receive UDP |
| multicast. |
| |
| .. option:: ttl=int : [netsplice] [net] |
| |
| Time-to-live value for outgoing UDP multicast packets. Default: 1. |
| |
| .. option:: nodelay=bool : [netsplice] [net] |
| |
| Set TCP_NODELAY on TCP connections. |
| |
| .. option:: protocol=str, proto=str : [netsplice] [net] |
| |
| The network protocol to use. Accepted values are: |
| |
| **tcp** |
| Transmission control protocol. |
| **tcpv6** |
| Transmission control protocol V6. |
| **udp** |
| User datagram protocol. |
| **udpv6** |
| User datagram protocol V6. |
| **unix** |
| UNIX domain socket. |
| |
| When the protocol is TCP or UDP, the port must also be given, as well as the |
| hostname if the job is a TCP listener or UDP reader. For unix sockets, the |
| normal :option:`filename` option should be used and the port is invalid. |
| |
| .. option:: listen : [netsplice] [net] |
| |
| For TCP network connections, tell fio to listen for incoming connections |
| rather than initiating an outgoing connection. The :option:`hostname` must |
| be omitted if this option is used. |
| |
| .. option:: pingpong : [netsplice] [net] |
| |
| Normally a network writer will just continue writing data, and a network |
| reader will just consume packages. If ``pingpong=1`` is set, a writer will |
| send its normal payload to the reader, then wait for the reader to send the |
| same payload back. This allows fio to measure network latencies. The |
| submission and completion latencies then measure local time spent sending or |
| receiving, and the completion latency measures how long it took for the |
| other end to receive and send back. For UDP multicast traffic |
| ``pingpong=1`` should only be set for a single reader when multiple readers |
| are listening to the same address. |
| |
| .. option:: window_size : [netsplice] [net] |
| |
| Set the desired socket buffer size for the connection. |
| |
| .. option:: mss : [netsplice] [net] |
| |
| Set the TCP maximum segment size (TCP_MAXSEG). |
| |
| .. option:: donorname=str : [e4defrag] |
| |
| File will be used as a block donor (swap extents between files). |
| |
| .. option:: inplace=int : [e4defrag] |
| |
| Configure donor file blocks allocation strategy: |
| |
| **0** |
| Default. Preallocate donor's file on init. |
| **1** |
| Allocate space immediately inside defragment event, and free right |
| after event. |
| |
| .. option:: clustername=str : [rbd,rados] |
| |
| Specifies the name of the Ceph cluster. |
| |
| .. option:: rbdname=str : [rbd] |
| |
| Specifies the name of the RBD. |
| |
| .. option:: pool=str : [rbd,rados] |
| |
| Specifies the name of the Ceph pool containing RBD or RADOS data. |
| |
| .. option:: clientname=str : [rbd,rados] |
| |
| Specifies the username (without the 'client.' prefix) used to access the |
| Ceph cluster. If the *clustername* is specified, the *clientname* shall be |
| the full *type.id* string. If no type. prefix is given, fio will add |
| 'client.' by default. |
| |
| .. option:: busy_poll=bool : [rbd,rados] |
| |
| Poll store instead of waiting for completion. Usually this provides better |
| throughput at cost of higher(up to 100%) CPU utilization. |
| |
| .. option:: touch_objects=bool : [rados] |
| |
| During initialization, touch (create if do not exist) all objects (files). |
| Touching all objects affects ceph caches and likely impacts test results. |
| Enabled by default. |
| |
| .. option:: skip_bad=bool : [mtd] |
| |
| Skip operations against known bad blocks. |
| |
| .. option:: hdfsdirectory : [libhdfs] |
| |
| libhdfs will create chunk in this HDFS directory. |
| |
| .. option:: chunk_size : [libhdfs] |
| |
| The size of the chunk to use for each file. |
| |
| .. option:: verb=str : [rdma] |
| |
| The RDMA verb to use on this side of the RDMA ioengine connection. Valid |
| values are write, read, send and recv. These correspond to the equivalent |
| RDMA verbs (e.g. write = rdma_write etc.). Note that this only needs to be |
| specified on the client side of the connection. See the examples folder. |
| |
| .. option:: bindname=str : [rdma] |
| |
| The name to use to bind the local RDMA-CM connection to a local RDMA device. |
| This could be a hostname or an IPv4 or IPv6 address. On the server side this |
| will be passed into the rdma_bind_addr() function and on the client site it |
| will be used in the rdma_resolve_add() function. This can be useful when |
| multiple paths exist between the client and the server or in certain loopback |
| configurations. |
| |
| .. option:: stat_type=str : [filestat] |
| |
| Specify stat system call type to measure lookup/getattr performance. |
| Default is **stat** for :manpage:`stat(2)`. |
| |
| .. option:: readfua=bool : [sg] |
| |
| With readfua option set to 1, read operations include |
| the force unit access (fua) flag. Default is 0. |
| |
| .. option:: writefua=bool : [sg] |
| |
| With writefua option set to 1, write operations include |
| the force unit access (fua) flag. Default is 0. |
| |
| .. option:: sg_write_mode=str : [sg] |
| |
| Specify the type of write commands to issue. This option can take three values: |
| |
| **write** |
| This is the default where write opcodes are issued as usual. |
| **verify** |
| Issue WRITE AND VERIFY commands. The BYTCHK bit is set to 0. This |
| directs the device to carry out a medium verification with no data |
| comparison. The writefua option is ignored with this selection. |
| **same** |
| Issue WRITE SAME commands. This transfers a single block to the device |
| and writes this same block of data to a contiguous sequence of LBAs |
| beginning at the specified offset. fio's block size parameter specifies |
| the amount of data written with each command. However, the amount of data |
| actually transferred to the device is equal to the device's block |
| (sector) size. For a device with 512 byte sectors, blocksize=8k will |
| write 16 sectors with each command. fio will still generate 8k of data |
| for each command but only the first 512 bytes will be used and |
| transferred to the device. The writefua option is ignored with this |
| selection. |
| |
| .. option:: hipri : [sg] |
| |
| If this option is set, fio will attempt to use polled IO completions. |
| This will have a similar effect as (io_uring)hipri. Only SCSI READ and |
| WRITE commands will have the SGV4_FLAG_HIPRI set (not UNMAP (trim) nor |
| VERIFY). Older versions of the Linux sg driver that do not support |
| hipri will simply ignore this flag and do normal IO. The Linux SCSI |
| Low Level Driver (LLD) that "owns" the device also needs to support |
| hipri (also known as iopoll and mq_poll). The MegaRAID driver is an |
| example of a SCSI LLD. Default: clear (0) which does normal |
| (interrupted based) IO. |
| |
| .. option:: http_host=str : [http] |
| |
| Hostname to connect to. For S3, this could be the bucket hostname. |
| Default is **localhost** |
| |
| .. option:: http_user=str : [http] |
| |
| Username for HTTP authentication. |
| |
| .. option:: http_pass=str : [http] |
| |
| Password for HTTP authentication. |
| |
| .. option:: https=str : [http] |
| |
| Enable HTTPS instead of http. *on* enables HTTPS; *insecure* |
| will enable HTTPS, but disable SSL peer verification (use with |
| caution!). Default is **off** |
| |
| .. option:: http_mode=str : [http] |
| |
| Which HTTP access mode to use: *webdav*, *swift*, or *s3*. |
| Default is **webdav** |
| |
| .. option:: http_s3_region=str : [http] |
| |
| The S3 region/zone string. |
| Default is **us-east-1** |
| |
| .. option:: http_s3_key=str : [http] |
| |
| The S3 secret key. |
| |
| .. option:: http_s3_keyid=str : [http] |
| |
| The S3 key/access id. |
| |
| .. option:: http_swift_auth_token=str : [http] |
| |
| The Swift auth token. See the example configuration file on how |
| to retrieve this. |
| |
| .. option:: http_verbose=int : [http] |
| |
| Enable verbose requests from libcurl. Useful for debugging. 1 |
| turns on verbose logging from libcurl, 2 additionally enables |
| HTTP IO tracing. Default is **0** |
| |
| .. option:: uri=str : [nbd] |
| |
| Specify the NBD URI of the server to test. The string |
| is a standard NBD URI |
| (see https://github.com/NetworkBlockDevice/nbd/tree/master/doc). |
| Example URIs: nbd://localhost:10809 |
| nbd+unix:///?socket=/tmp/socket |
| nbds://tlshost/exportname |
| |
| .. option:: gpu_dev_ids=str : [libcufile] |
| |
| Specify the GPU IDs to use with CUDA. This is a colon-separated list of |
| int. GPUs are assigned to workers roundrobin. Default is 0. |
| |
| .. option:: cuda_io=str : [libcufile] |
| |
| Specify the type of I/O to use with CUDA. Default is **cufile**. |
| |
| **cufile** |
| Use libcufile and nvidia-fs. This option performs I/O directly |
| between a GPUDirect Storage filesystem and GPU buffers, |
| avoiding use of a bounce buffer. If :option:`verify` is set, |
| cudaMemcpy is used to copy verificaton data between RAM and GPU. |
| Verification data is copied from RAM to GPU before a write |
| and from GPU to RAM after a read. :option:`direct` must be 1. |
| **posix** |
| Use POSIX to perform I/O with a RAM buffer, and use cudaMemcpy |
| to transfer data between RAM and the GPUs. Data is copied from |
| GPU to RAM before a write and copied from RAM to GPU after a |
| read. :option:`verify` does not affect use of cudaMemcpy. |
| |
| .. option:: pool=str : [dfs] |
| |
| Specify the UUID of the DAOS pool to connect to. |
| |
| .. option:: cont=str : [dfs] |
| |
| Specify the UUID of the DAOS container to open. |
| |
| .. option:: chunk_size=int : [dfs] |
| |
| Specificy a different chunk size (in bytes) for the dfs file. |
| Use DAOS container's chunk size by default. |
| |
| .. option:: object_class=str : [dfs] |
| |
| Specificy a different object class for the dfs file. |
| Use DAOS container's object class by default. |
| |
| I/O depth |
| ~~~~~~~~~ |
| |
| .. option:: iodepth=int |
| |
| Number of I/O units to keep in flight against the file. Note that |
| increasing *iodepth* beyond 1 will not affect synchronous ioengines (except |
| for small degrees when :option:`verify_async` is in use). Even async |
| engines may impose OS restrictions causing the desired depth not to be |
| achieved. This may happen on Linux when using libaio and not setting |
| :option:`direct`\=1, since buffered I/O is not async on that OS. Keep an |
| eye on the I/O depth distribution in the fio output to verify that the |
| achieved depth is as expected. Default: 1. |
| |
| .. option:: iodepth_batch_submit=int, iodepth_batch=int |
| |
| This defines how many pieces of I/O to submit at once. It defaults to 1 |
| which means that we submit each I/O as soon as it is available, but can be |
| raised to submit bigger batches of I/O at the time. If it is set to 0 the |
| :option:`iodepth` value will be used. |
| |
| .. option:: iodepth_batch_complete_min=int, iodepth_batch_complete=int |
| |
| This defines how many pieces of I/O to retrieve at once. It defaults to 1 |
| which means that we'll ask for a minimum of 1 I/O in the retrieval process |
| from the kernel. The I/O retrieval will go on until we hit the limit set by |
| :option:`iodepth_low`. If this variable is set to 0, then fio will always |
| check for completed events before queuing more I/O. This helps reduce I/O |
| latency, at the cost of more retrieval system calls. |
| |
| .. option:: iodepth_batch_complete_max=int |
| |
| This defines maximum pieces of I/O to retrieve at once. This variable should |
| be used along with :option:`iodepth_batch_complete_min`\=int variable, |
| specifying the range of min and max amount of I/O which should be |
| retrieved. By default it is equal to the :option:`iodepth_batch_complete_min` |
| value. |
| |
| Example #1:: |
| |
| iodepth_batch_complete_min=1 |
| iodepth_batch_complete_max=<iodepth> |
| |
| which means that we will retrieve at least 1 I/O and up to the whole |
| submitted queue depth. If none of I/O has been completed yet, we will wait. |
| |
| Example #2:: |
| |
| iodepth_batch_complete_min=0 |
| iodepth_batch_complete_max=<iodepth> |
| |
| which means that we can retrieve up to the whole submitted queue depth, but |
| if none of I/O has been completed yet, we will NOT wait and immediately exit |
| the system call. In this example we simply do polling. |
| |
| .. option:: iodepth_low=int |
| |
| The low water mark indicating when to start filling the queue |
| again. Defaults to the same as :option:`iodepth`, meaning that fio will |
| attempt to keep the queue full at all times. If :option:`iodepth` is set to |
| e.g. 16 and *iodepth_low* is set to 4, then after fio has filled the queue of |
| 16 requests, it will let the depth drain down to 4 before starting to fill |
| it again. |
| |
| .. option:: serialize_overlap=bool |
| |
| Serialize in-flight I/Os that might otherwise cause or suffer from data races. |
| When two or more I/Os are submitted simultaneously, there is no guarantee that |
| the I/Os will be processed or completed in the submitted order. Further, if |
| two or more of those I/Os are writes, any overlapping region between them can |
| become indeterminate/undefined on certain storage. These issues can cause |
| verification to fail erratically when at least one of the racing I/Os is |
| changing data and the overlapping region has a non-zero size. Setting |
| ``serialize_overlap`` tells fio to avoid provoking this behavior by explicitly |
| serializing in-flight I/Os that have a non-zero overlap. Note that setting |
| this option can reduce both performance and the :option:`iodepth` achieved. |
| |
| This option only applies to I/Os issued for a single job except when it is |
| enabled along with :option:`io_submit_mode`\=offload. In offload mode, fio |
| will check for overlap among all I/Os submitted by offload jobs with :option:`serialize_overlap` |
| enabled. |
| |
| Default: false. |
| |
| .. option:: io_submit_mode=str |
| |
| This option controls how fio submits the I/O to the I/O engine. The default |
| is `inline`, which means that the fio job threads submit and reap I/O |
| directly. If set to `offload`, the job threads will offload I/O submission |
| to a dedicated pool of I/O threads. This requires some coordination and thus |
| has a bit of extra overhead, especially for lower queue depth I/O where it |
| can increase latencies. The benefit is that fio can manage submission rates |
| independently of the device completion rates. This avoids skewed latency |
| reporting if I/O gets backed up on the device side (the coordinated omission |
| problem). Note that this option cannot reliably be used with async IO |
| engines. |
| |
| |
| I/O rate |
| ~~~~~~~~ |
| |
| .. option:: thinktime=time |
| |
| Stall the job for the specified period of time after an I/O has completed before issuing the |
| next. May be used to simulate processing being done by an application. |
| When the unit is omitted, the value is interpreted in microseconds. See |
| :option:`thinktime_blocks` and :option:`thinktime_spin`. |
| |
| .. option:: thinktime_spin=time |
| |
| Only valid if :option:`thinktime` is set - pretend to spend CPU time doing |
| something with the data received, before falling back to sleeping for the |
| rest of the period specified by :option:`thinktime`. When the unit is |
| omitted, the value is interpreted in microseconds. |
| |
| .. option:: thinktime_blocks=int |
| |
| Only valid if :option:`thinktime` is set - control how many blocks to issue, |
| before waiting :option:`thinktime` usecs. If not set, defaults to 1 which will make |
| fio wait :option:`thinktime` usecs after every block. This effectively makes any |
| queue depth setting redundant, since no more than 1 I/O will be queued |
| before we have to complete it and do our :option:`thinktime`. In other words, this |
| setting effectively caps the queue depth if the latter is larger. |
| |
| .. option:: thinktime_blocks_type=str |
| |
| Only valid if :option:`thinktime` is set - control how :option:`thinktime_blocks` |
| triggers. The default is `complete`, which triggers thinktime when fio completes |
| :option:`thinktime_blocks` blocks. If this is set to `issue`, then the trigger happens |
| at the issue side. |
| |
| .. option:: rate=int[,int][,int] |
| |
| Cap the bandwidth used by this job. The number is in bytes/sec, the normal |
| suffix rules apply. Comma-separated values may be specified for reads, |
| writes, and trims as described in :option:`blocksize`. |
| |
| For example, using `rate=1m,500k` would limit reads to 1MiB/sec and writes to |
| 500KiB/sec. Capping only reads or writes can be done with `rate=,500k` or |
| `rate=500k,` where the former will only limit writes (to 500KiB/sec) and the |
| latter will only limit reads. |
| |
| .. option:: rate_min=int[,int][,int] |
| |
| Tell fio to do whatever it can to maintain at least this bandwidth. Failing |
| to meet this requirement will cause the job to exit. Comma-separated values |
| may be specified for reads, writes, and trims as described in |
| :option:`blocksize`. |
| |
| .. option:: rate_iops=int[,int][,int] |
| |
| Cap the bandwidth to this number of IOPS. Basically the same as |
| :option:`rate`, just specified independently of bandwidth. If the job is |
| given a block size range instead of a fixed value, the smallest block size |
| is used as the metric. Comma-separated values may be specified for reads, |
| writes, and trims as described in :option:`blocksize`. |
| |
| .. option:: rate_iops_min=int[,int][,int] |
| |
| If fio doesn't meet this rate of I/O, it will cause the job to exit. |
| Comma-separated values may be specified for reads, writes, and trims as |
| described in :option:`blocksize`. |
| |
| .. option:: rate_process=str |
| |
| This option controls how fio manages rated I/O submissions. The default is |
| `linear`, which submits I/O in a linear fashion with fixed delays between |
| I/Os that gets adjusted based on I/O completion rates. If this is set to |
| `poisson`, fio will submit I/O based on a more real world random request |
| flow, known as the Poisson process |
| (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda will be |
| 10^6 / IOPS for the given workload. |
| |
| .. option:: rate_ignore_thinktime=bool |
| |
| By default, fio will attempt to catch up to the specified rate setting, |
| if any kind of thinktime setting was used. If this option is set, then |
| fio will ignore the thinktime and continue doing IO at the specified |
| rate, instead of entering a catch-up mode after thinktime is done. |
| |
| |
| I/O latency |
| ~~~~~~~~~~~ |
| |
| .. option:: latency_target=time |
| |
| If set, fio will attempt to find the max performance point that the given |
| workload will run at while maintaining a latency below this target. When |
| the unit is omitted, the value is interpreted in microseconds. See |
| :option:`latency_window` and :option:`latency_percentile`. |
| |
| .. option:: latency_window=time |
| |
| Used with :option:`latency_target` to specify the sample window that the job |
| is run at varying queue depths to test the performance. When the unit is |
| omitted, the value is interpreted in microseconds. |
| |
| .. option:: latency_percentile=float |
| |
| The percentage of I/Os that must fall within the criteria specified by |
| :option:`latency_target` and :option:`latency_window`. If not set, this |
| defaults to 100.0, meaning that all I/Os must be equal or below to the value |
| set by :option:`latency_target`. |
| |
| .. option:: latency_run=bool |
| |
| Used with :option:`latency_target`. If false (default), fio will find |
| the highest queue depth that meets :option:`latency_target` and exit. If |
| true, fio will continue running and try to meet :option:`latency_target` |
| by adjusting queue depth. |
| |
| .. option:: max_latency=time[,time][,time] |
| |
| If set, fio will exit the job with an ETIMEDOUT error if it exceeds this |
| maximum latency. When the unit is omitted, the value is interpreted in |
| microseconds. Comma-separated values may be specified for reads, writes, |
| and trims as described in :option:`blocksize`. |
| |
| .. option:: rate_cycle=int |
| |
| Average bandwidth for :option:`rate` and :option:`rate_min` over this number |
| of milliseconds. Defaults to 1000. |
| |
| |
| I/O replay |
| ~~~~~~~~~~ |
| |
| .. option:: write_iolog=str |
| |
| Write the issued I/O patterns to the specified file. See |
| :option:`read_iolog`. Specify a separate file for each job, otherwise the |
| iologs will be interspersed and the file may be corrupt. |
| |
| .. option:: read_iolog=str |
| |
| Open an iolog with the specified filename and replay the I/O patterns it |
| contains. This can be used to store a workload and replay it sometime |
| later. The iolog given may also be a blktrace binary file, which allows fio |
| to replay a workload captured by :command:`blktrace`. See |
| :manpage:`blktrace(8)` for how to capture such logging data. For blktrace |
| replay, the file needs to be turned into a blkparse binary data file first |
| (``blkparse <device> -o /dev/null -d file_for_fio.bin``). |
| You can specify a number of files by separating the names with a ':' |
| character. See the :option:`filename` option for information on how to |
| escape ':' characters within the file names. These files will |
| be sequentially assigned to job clones created by :option:`numjobs`. |
| '-' is a reserved name, meaning read from stdin, notably if |
| :option:`filename` is set to '-' which means stdin as well, then |
| this flag can't be set to '-'. |
| |
| .. option:: read_iolog_chunked=bool |
| |
| Determines how iolog is read. If false(default) entire :option:`read_iolog` |
| will be read at once. If selected true, input from iolog will be read |
| gradually. Useful when iolog is very large, or it is generated. |
| |
| .. option:: merge_blktrace_file=str |
| |
| When specified, rather than replaying the logs passed to :option:`read_iolog`, |
| the logs go through a merge phase which aggregates them into a single |
| blktrace. The resulting file is then passed on as the :option:`read_iolog` |
| parameter. The intention here is to make the order of events consistent. |
| This limits the influence of the scheduler compared to replaying multiple |
| blktraces via concurrent jobs. |
| |
| .. option:: merge_blktrace_scalars=float_list |
| |
| This is a percentage based option that is index paired with the list of |
| files passed to :option:`read_iolog`. When merging is performed, scale |
| the time of each event by the corresponding amount. For example, |
| ``--merge_blktrace_scalars="50:100"`` runs the first trace in halftime |
| and the second trace in realtime. This knob is separately tunable from |
| :option:`replay_time_scale` which scales the trace during runtime and |
| does not change the output of the merge unlike this option. |
| |
| .. option:: merge_blktrace_iters=float_list |
| |
| This is a whole number option that is index paired with the list of files |
| passed to :option:`read_iolog`. When merging is performed, run each trace |
| for the specified number of iterations. For example, |
| ``--merge_blktrace_iters="2:1"`` runs the first trace for two iterations |
| and the second trace for one iteration. |
| |
| .. option:: replay_no_stall=bool |
| |
| When replaying I/O with :option:`read_iolog` the default behavior is to |
| attempt to respect the timestamps within the log and replay them with the |
| appropriate delay between IOPS. By setting this variable fio will not |
| respect the timestamps and attempt to replay them as fast as possible while |
| still respecting ordering. The result is the same I/O pattern to a given |
| device, but different timings. |
| |
| .. option:: replay_time_scale=int |
| |
| When replaying I/O with :option:`read_iolog`, fio will honor the |
| original timing in the trace. With this option, it's possible to scale |
| the time. It's a percentage option, if set to 50 it means run at 50% |
| the original IO rate in the trace. If set to 200, run at twice the |
| original IO rate. Defaults to 100. |
| |
| .. option:: replay_redirect=str |
| |
| While replaying I/O patterns using :option:`read_iolog` the default behavior |
| is to replay the IOPS onto the major/minor device that each IOP was recorded |
| from. This is sometimes undesirable because on a different machine those |
| major/minor numbers can map to a different device. Changing hardware on the |
| same system can also result in a different major/minor mapping. |
| ``replay_redirect`` causes all I/Os to be replayed onto the single specified |
| device regardless of the device it was recorded |
| from. i.e. :option:`replay_redirect`\= :file:`/dev/sdc` would cause all I/O |
| in the blktrace or iolog to be replayed onto :file:`/dev/sdc`. This means |
| multiple devices will be replayed onto a single device, if the trace |
| contains multiple devices. If you want multiple devices to be replayed |
| concurrently to multiple redirected devices you must blkparse your trace |
| into separate traces and replay them with independent fio invocations. |
| Unfortunately this also breaks the strict time ordering between multiple |
| device accesses. |
| |
| .. option:: replay_align=int |
| |
| Force alignment of the byte offsets in a trace to this value. The value |
| must be a power of 2. |
| |
| .. option:: replay_scale=int |
| |
| Scale byte offsets down by this factor when replaying traces. Should most |
| likely use :option:`replay_align` as well. |
| |
| .. option:: replay_skip=str |
| |
| Sometimes it's useful to skip certain IO types in a replay trace. |
| This could be, for instance, eliminating the writes in the trace. |
| Or not replaying the trims/discards, if you are redirecting to |
| a device that doesn't support them. This option takes a comma |
| separated list of read, write, trim, sync. |
| |
| |
| Threads, processes and job synchronization |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| .. option:: thread |
| |
| Fio defaults to creating jobs by using fork, however if this option is |
| given, fio will create jobs by using POSIX Threads' function |
| :manpage:`pthread_create(3)` to create threads instead. |
| |
| .. option:: wait_for=str |
| |
| If set, the current job won't be started until all workers of the specified |
| waitee job are done. |
| |
| ``wait_for`` operates on the job name basis, so there are a few |
| limitations. First, the waitee must be defined prior to the waiter job |
| (meaning no forward references). Second, if a job is being referenced as a |
| waitee, it must have a unique name (no duplicate waitees). |
| |
| .. option:: nice=int |
| |
| Run the job with the given nice value. See man :manpage:`nice(2)`. |
| |
| On Windows, values less than -15 set the process class to "High"; -1 through |
| -15 set "Above Normal"; 1 through 15 "Below Normal"; and above 15 "Idle" |
| priority class. |
| |
| .. option:: prio=int |
| |
| Set the I/O priority value of this job. Linux limits us to a positive value |
| between 0 and 7, with 0 being the highest. See man |
| :manpage:`ionice(1)`. Refer to an appropriate manpage for other operating |
| systems since meaning of priority may differ. For per-command priority |
| setting, see I/O engine specific `cmdprio_percentage` and `hipri_percentage` |
| options. |
| |
| .. option:: prioclass=int |
| |
| Set the I/O priority class. See man :manpage:`ionice(1)`. For per-command |
| priority setting, see I/O engine specific `cmdprio_percentage` and |
| `hipri_percentage` options. |
| |
| .. option:: cpus_allowed=str |
| |
| Controls the same options as :option:`cpumask`, but accepts a textual |
| specification of the permitted CPUs instead and CPUs are indexed from 0. So |
| to use CPUs 0 and 5 you would specify ``cpus_allowed=0,5``. This option also |
| allows a range of CPUs to be specified -- say you wanted a binding to CPUs |
| 0, 5, and 8 to 15, you would set ``cpus_allowed=0,5,8-15``. |
| |
| On Windows, when ``cpus_allowed`` is unset only CPUs from fio's current |
| processor group will be used and affinity settings are inherited from the |
| system. An fio build configured to target Windows 7 makes options that set |
| CPUs processor group aware and values will set both the processor group |
| and a CPU from within that group. For example, on a system where processor |
| group 0 has 40 CPUs and processor group 1 has 32 CPUs, ``cpus_allowed`` |
| values between 0 and 39 will bind CPUs from processor group 0 and |
| ``cpus_allowed`` values between 40 and 71 will bind CPUs from processor |
| group 1. When using ``cpus_allowed_policy=shared`` all CPUs specified by a |
| single ``cpus_allowed`` option must be from the same processor group. For |
| Windows fio builds not built for Windows 7, CPUs will only be selected from |
| (and be relative to) whatever processor group fio happens to be running in |
| and CPUs from other processor groups cannot be used. |
| |
| .. option:: cpus_allowed_policy=str |
| |
| Set the policy of how fio distributes the CPUs specified by |
| :option:`cpus_allowed` or :option:`cpumask`. Two policies are supported: |
| |
| **shared** |
| All jobs will share the CPU set specified. |
| **split** |
| Each job will get a unique CPU from the CPU set. |
| |
| **shared** is the default behavior, if the option isn't specified. If |
| **split** is specified, then fio will assign one cpu per job. If not |
| enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs |
| in the set. |
| |
| .. option:: cpumask=int |
| |
| Set the CPU affinity of this job. The parameter given is a bit mask of |
| allowed CPUs the job may run on. So if you want the allowed CPUs to be 1 |
| and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man |
| :manpage:`sched_setaffinity(2)`. This may not work on all supported |
| operating systems or kernel versions. This option doesn't work well for a |
| higher CPU count than what you can store in an integer mask, so it can only |
| control cpus 1-32. For boxes with larger CPU counts, use |
| :option:`cpus_allowed`. |
| |
| .. option:: numa_cpu_nodes=str |
| |
| Set this job running on specified NUMA nodes' CPUs. The arguments allow |
| comma delimited list of cpu numbers, A-B ranges, or `all`. Note, to enable |
| NUMA options support, fio must be built on a system with libnuma-dev(el) |
| installed. |
| |
| .. option:: numa_mem_policy=str |
| |
| Set this job's memory policy and corresponding NUMA nodes. Format of the |
| arguments:: |
| |
| <mode>[:<nodelist>] |
| |
| ``mode`` is one of the following memory policies: ``default``, ``prefer``, |
| ``bind``, ``interleave`` or ``local``. For ``default`` and ``local`` memory |
| policies, no node needs to be specified. For ``prefer``, only one node is |
| allowed. For ``bind`` and ``interleave`` the ``nodelist`` may be as |
| follows: a comma delimited list of numbers, A-B ranges, or `all`. |
| |
| .. option:: cgroup=str |
| |
| Add job to this control group. If it doesn't exist, it will be created. The |
| system must have a mounted cgroup blkio mount point for this to work. If |
| your system doesn't have it mounted, you can do so with:: |
| |
| # mount -t cgroup -o blkio none /cgroup |
| |
| .. option:: cgroup_weight=int |
| |
| Set the weight of the cgroup to this value. See the documentation that comes |
| with the kernel, allowed values are in the range of 100..1000. |
| |
| .. option:: cgroup_nodelete=bool |
| |
| Normally fio will delete the cgroups it has created after the job |
| completion. To override this behavior and to leave cgroups around after the |
| job completion, set ``cgroup_nodelete=1``. This can be useful if one wants |
| to inspect various cgroup files after job completion. Default: false. |
| |
| .. option:: flow_id=int |
| |
| The ID of the flow. If not specified, it defaults to being a global |
| flow. See :option:`flow`. |
| |
| .. option:: flow=int |
| |
| Weight in token-based flow control. If this value is used, then there is a |
| 'flow counter' which is used to regulate the proportion of activity between |
| two or more jobs. Fio attempts to keep this flow counter near zero. The |
| ``flow`` parameter stands for how much should be added or subtracted to the |
| flow counter on each iteration of the main I/O loop. That is, if one job has |
| ``flow=8`` and another job has ``flow=-1``, then there will be a roughly 1:8 |
| ratio in how much one runs vs the other. |
| |
| .. option:: flow_sleep=int |
| |
| The period of time, in microseconds, to wait after the flow counter |
| has exceeded its proportion before retrying operations. |
| |
| .. option:: stonewall, wait_for_previous |
| |
| Wait for preceding jobs in the job file to exit, before starting this |
| one. Can be used to insert serialization points in the job file. A stone |
| wall also implies starting a new reporting group, see |
| :option:`group_reporting`. |
| |
| .. option:: exitall |
| |
| By default, fio will continue running all other jobs when one job finishes. |
| Sometimes this is not the desired action. Setting ``exitall`` will instead |
| make fio terminate all jobs in the same group, as soon as one job of that |
| group finishes. |
| |
| .. option:: exit_what |
| |
| By default, fio will continue running all other jobs when one job finishes. |
| Sometimes this is not the desired action. Setting ``exit_all`` will |
| instead make fio terminate all jobs in the same group. The option |
| ``exit_what`` allows to control which jobs get terminated when ``exitall`` is |
| enabled. The default is ``group`` and does not change the behaviour of |
| ``exitall``. The setting ``all`` terminates all jobs. The setting ``stonewall`` |
| terminates all currently running jobs across all groups and continues execution |
| with the next stonewalled group. |
| |
| .. option:: exec_prerun=str |
| |
| Before running this job, issue the command specified through |
| :manpage:`system(3)`. Output is redirected in a file called |
| :file:`jobname.prerun.txt`. |
| |
| .. option:: exec_postrun=str |
| |
| After the job completes, issue the command specified though |
| :manpage:`system(3)`. Output is redirected in a file called |
| :file:`jobname.postrun.txt`. |
| |
| .. option:: uid=int |
| |
| Instead of running as the invoking user, set the user ID to this value |
| before the thread/process does any work. |
| |
| .. option:: gid=int |
| |
| Set group ID, see :option:`uid`. |
| |
| |
| Verification |
| ~~~~~~~~~~~~ |
| |
| .. option:: verify_only |
| |
| Do not perform specified workload, only verify data still matches previous |
| invocation of this workload. This option allows one to check data multiple |
| times at a later date without overwriting it. This option makes sense only |
| for workloads that write data, and does not support workloads with the |
| :option:`time_based` option set. |
| |
| .. option:: do_verify=bool |
| |
| Run the verify phase after a write phase. Only valid if :option:`verify` is |
| set. Default: true. |
| |
| .. option:: verify=str |
| |
| If writing to a file, fio can verify the file contents after each iteration |
| of the job. Each verification method also implies verification of special |
| header, which is written to the beginning of each block. This header also |
| includes meta information, like offset of the block, block number, timestamp |
| when block was written, etc. :option:`verify` can be combined with |
| :option:`verify_pattern` option. The allowed values are: |
| |
| **md5** |
| Use an md5 sum of the data area and store it in the header of |
| each block. |
| |
| **crc64** |
| Use an experimental crc64 sum of the data area and store it in the |
| header of each block. |
| |
| **crc32c** |
| Use a crc32c sum of the data area and store it in the header of |
| each block. This will automatically use hardware acceleration |
| (e.g. SSE4.2 on an x86 or CRC crypto extensions on ARM64) but will |
| fall back to software crc32c if none is found. Generally the |
| fastest checksum fio supports when hardware accelerated. |
| |
| **crc32c-intel** |
| Synonym for crc32c. |
| |
| **crc32** |
| Use a crc32 sum of the data area and store it in the header of each |
| block. |
| |
| **crc16** |
| Use a crc16 sum of the data area and store it in the header of each |
| block. |
| |
| **crc7** |
| Use a crc7 sum of the data area and store it in the header of each |
| block. |
| |
| **xxhash** |
| Use xxhash as the checksum function. Generally the fastest software |
| checksum that fio supports. |
| |
| **sha512** |
| Use sha512 as the checksum function. |
| |
| **sha256** |
| Use sha256 as the checksum function. |
| |
| **sha1** |
| Use optimized sha1 as the checksum function. |
| |
| **sha3-224** |
| Use optimized sha3-224 as the checksum function. |
| |
| **sha3-256** |
| Use optimized sha3-256 as the checksum function. |
| |
| **sha3-384** |
| Use optimized sha3-384 as the checksum function. |
| |
| **sha3-512** |
| Use optimized sha3-512 as the checksum function. |
| |
| **meta** |
| This option is deprecated, since now meta information is included in |
| generic verification header and meta verification happens by |
| default. For detailed information see the description of the |
| :option:`verify` setting. This option is kept because of |
| compatibility's sake with old configurations. Do not use it. |
| |
| **pattern** |
| Verify a strict pattern. Normally fio includes a header with some |
| basic information and checksumming, but if this option is set, only |
| the specific pattern set with :option:`verify_pattern` is verified. |
| |
| **null** |
| Only pretend to verify. Useful for testing internals with |
| :option:`ioengine`\=null, not for much else. |
| |
| This option can be used for repeated burn-in tests of a system to make sure |
| that the written data is also correctly read back. If the data direction |
| given is a read or random read, fio will assume that it should verify a |
| previously written file. If the data direction includes any form of write, |
| the verify will be of the newly written data. |
| |
| To avoid false verification errors, do not use the norandommap option when |
| verifying data with async I/O engines and I/O depths > 1. Or use the |
| norandommap and the lfsr random generator together to avoid writing to the |
| same offset with muliple outstanding I/Os. |
| |
| .. option:: verify_offset=int |
| |
| Swap the verification header with data somewhere else in the block before |
| writing. It is swapped back before verifying. |
| |
| .. option:: verify_interval=int |
| |
| Write the verification header at a finer granularity than the |
| :option:`blocksize`. It will be written for chunks the size of |
| ``verify_interval``. :option:`blocksize` should divide this evenly. |
| |
| .. option:: verify_pattern=str |
| |
| If set, fio will fill the I/O buffers with this pattern. Fio defaults to |
| filling with totally random bytes, but sometimes it's interesting to fill |
| with a known pattern for I/O verification purposes. Depending on the width |
| of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time (it can |
| be either a decimal or a hex number). The ``verify_pattern`` if larger than |
| a 32-bit quantity has to be a hex number that starts with either "0x" or |
| "0X". Use with :option:`verify`. Also, ``verify_pattern`` supports %o |
| format, which means that for each block offset will be written and then |
| verified back, e.g.:: |
| |
| verify_pattern=%o |
| |
| Or use combination of everything:: |
| |
| verify_pattern=0xff%o"abcd"-12 |
| |
| .. option:: verify_fatal=bool |
| |
| Normally fio will keep checking the entire contents before quitting on a |
| block verification failure. If this option is set, fio will exit the job on |
| the first observed failure. Default: false. |
| |
| .. option:: verify_dump=bool |
| |
| If set, dump the contents of both the original data block and the data block |
| we read off disk to files. This allows later analysis to inspect just what |
| kind of data corruption occurred. Off by default. |
| |
| .. option:: verify_async=int |
| |
| Fio will normally verify I/O inline from the submitting thread. This option |
| takes an integer describing how many async offload threads to create for I/O |
| verification instead, causing fio to offload the duty of verifying I/O |
| contents to one or more separate threads. If using this offload option, even |
| sync I/O engines can benefit from using an :option:`iodepth` setting higher |
| than 1, as it allows them to have I/O in flight while verifies are running. |
| Defaults to 0 async threads, i.e. verification is not asynchronous. |
| |
| .. option:: verify_async_cpus=str |
| |
| Tell fio to set the given CPU affinity on the async I/O verification |
| threads. See :option:`cpus_allowed` for the format used. |
| |
| .. option:: verify_backlog=int |
| |
| Fio will normally verify the written contents of a job that utilizes verify |
| once that job has completed. In other words, everything is written then |
| everything is read back and verified. You may want to verify continually |
| instead for a variety of reasons. Fio stores the meta data associated with |
| an I/O block in memory, so for large verify workloads, quite a bit of memory |
| would be used up holding this meta data. If this option is enabled, fio will |
| write only N blocks before verifying these blocks. |
| |
| .. option:: verify_backlog_batch=int |
| |
| Control how many blocks fio will verify if :option:`verify_backlog` is |
| set. If not set, will default to the value of :option:`verify_backlog` |
| (meaning the entire queue is read back and verified). If |
| ``verify_backlog_batch`` is less than :option:`verify_backlog` then not all |
| blocks will be verified, if ``verify_backlog_batch`` is larger than |
| :option:`verify_backlog`, some blocks will be verified more than once. |
| |
| .. option:: verify_state_save=bool |
| |
| When a job exits during the write phase of a verify workload, save its |
| current state. This allows fio to replay up until that point, if the verify |
| state is loaded for the verify read phase. The format of the filename is, |
| roughly:: |
| |
| <type>-<jobname>-<jobindex>-verify.state. |
| |
| <type> is "local" for a local run, "sock" for a client/server socket |
| connection, and "ip" (192.168.0.1, for instance) for a networked |
| client/server connection. Defaults to true. |
| |
| .. option:: verify_state_load=bool |
| |
| If a verify termination trigger was used, fio stores the current write state |
| of each thread. This can be used at verification time so that fio knows how |
| far it should verify. Without this information, fio will run a full |
| verification pass, according to the settings in the job file used. Default |
| false. |
| |
| .. option:: trim_percentage=int |
| |
| Number of verify blocks to discard/trim. |
| |
| .. option:: trim_verify_zero=bool |
| |
| Verify that trim/discarded blocks are returned as zeros. |
| |
| .. option:: trim_backlog=int |
| |
| Trim after this number of blocks are written. |
| |
| .. option:: trim_backlog_batch=int |
| |
| Trim this number of I/O blocks. |
| |
| .. option:: experimental_verify=bool |
| |
| Enable experimental verification. |
| |
| Steady state |
| ~~~~~~~~~~~~ |
| |
| .. option:: steadystate=str:float, ss=str:float |
| |
| Define the criterion and limit for assessing steady state performance. The |
| first parameter designates the criterion whereas the second parameter sets |
| the threshold. When the criterion falls below the threshold for the |
| specified duration, the job will stop. For example, `iops_slope:0.1%` will |
| direct fio to terminate the job when the least squares regression slope |
| falls below 0.1% of the mean IOPS. If :option:`group_reporting` is enabled |
| this will apply to all jobs in the group. Below is the list of available |
| steady state assessment criteria. All assessments are carried out using only |
| data from the rolling collection window. Threshold limits can be expressed |
| as a fixed value or as a percentage of the mean in the collection window. |
| |
| When using this feature, most jobs should include the :option:`time_based` |
| and :option:`runtime` options or the :option:`loops` option so that fio does not |
| stop running after it has covered the full size of the specified file(s) or device(s). |
| |
| **iops** |
| Collect IOPS data. Stop the job if all individual IOPS measurements |
| are within the specified limit of the mean IOPS (e.g., ``iops:2`` |
| means that all individual IOPS values must be within 2 of the mean, |
| whereas ``iops:0.2%`` means that all individual IOPS values must be |
| within 0.2% of the mean IOPS to terminate the job). |
| |
| **iops_slope** |
| Collect IOPS data and calculate the least squares regression |
| slope. Stop the job if the slope falls below the specified limit. |
| |
| **bw** |
| Collect bandwidth data. Stop the job if all individual bandwidth |
| measurements are within the specified limit of the mean bandwidth. |
| |
| **bw_slope** |
| Collect bandwidth data and calculate the least squares regression |
| slope. Stop the job if the slope falls below the specified limit. |
| |
| .. option:: steadystate_duration=time, ss_dur=time |
| |
| A rolling window of this duration will be used to judge whether steady state |
| has been reached. Data will be collected once per second. The default is 0 |
| which disables steady state detection. When the unit is omitted, the |
| value is interpreted in seconds. |
| |
| .. option:: steadystate_ramp_time=time, ss_ramp=time |
| |
| Allow the job to run for the specified duration before beginning data |
| collection for checking the steady state job termination criterion. The |
| default is 0. When the unit is omitted, the value is interpreted in seconds. |
| |
| |
| Measurements and reporting |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| .. option:: per_job_logs=bool |
| |
| If set, this generates bw/clat/iops log with per file private filenames. If |
| not set, jobs with identical names will share the log filename. Default: |
| true. |
| |
| .. option:: group_reporting |
| |
| It may sometimes be interesting to display statistics for groups of jobs as |
| a whole instead of for each individual job. This is especially true if |
| :option:`numjobs` is used; looking at individual thread/process output |
| quickly becomes unwieldy. To see the final report per-group instead of |
| per-job, use :option:`group_reporting`. Jobs in a file will be part of the |
| same reporting group, unless if separated by a :option:`stonewall`, or by |
| using :option:`new_group`. |
| |
| .. option:: new_group |
| |
| Start a new reporting group. See: :option:`group_reporting`. If not given, |
| all jobs in a file will be part of the same reporting group, unless |
| separated by a :option:`stonewall`. |
| |
| .. option:: stats=bool |
| |
| By default, fio collects and shows final output results for all jobs |
| that run. If this option is set to 0, then fio will ignore it in |
| the final stat output. |
| |
| .. option:: write_bw_log=str |
| |
| If given, write a bandwidth log for this job. Can be used to store data of |
| the bandwidth of the jobs in their lifetime. |
| |
| If no str argument is given, the default filename of |
| :file:`jobname_type.x.log` is used. Even when the argument is given, fio |
| will still append the type of log. So if one specifies:: |
| |
| write_bw_log=foo |
| |
| The actual log name will be :file:`foo_bw.x.log` where `x` is the index |
| of the job (`1..N`, where `N` is the number of jobs). If |
| :option:`per_job_logs` is false, then the filename will not include the |
| `.x` job index. |
| |
| The included :command:`fio_generate_plots` script uses :command:`gnuplot` to turn these |
| text files into nice graphs. See `Log File Formats`_ for how data is |
| structured within the file. |
| |
| .. option:: write_lat_log=str |
| |
| Same as :option:`write_bw_log`, except this option creates I/O |
| submission (e.g., :file:`name_slat.x.log`), completion (e.g., |
| :file:`name_clat.x.log`), and total (e.g., :file:`name_lat.x.log`) |
| latency files instead. See :option:`write_bw_log` for details about |
| the filename format and `Log File Formats`_ for how data is structured |
| within the files. |
| |
| .. option:: write_hist_log=str |
| |
| Same as :option:`write_bw_log` but writes an I/O completion latency |
| histogram file (e.g., :file:`name_hist.x.log`) instead. Note that this |
| file will be empty unless :option:`log_hist_msec` has also been set. |
| See :option:`write_bw_log` for details about the filename format and |
| `Log File Formats`_ for how data is structured within the file. |
| |
| .. option:: write_iops_log=str |
| |
| Same as :option:`write_bw_log`, but writes an IOPS file (e.g. |
| :file:`name_iops.x.log`) instead. Because fio defaults to individual |
| I/O logging, the value entry in the IOPS log will be 1 unless windowed |
| logging (see :option:`log_avg_msec`) has been enabled. See |
| :option:`write_bw_log` for details about the filename format and `Log |
| File Formats`_ for how data is structured within the file. |
| |
| .. option:: log_avg_msec=int |
| |
| By default, fio will log an entry in the iops, latency, or bw log for every |
| I/O that completes. When writing to the disk log, that can quickly grow to a |
| very large size. Setting this option makes fio average the each log entry |
| over the specified period of time, reducing the resolution of the log. See |
| :option:`log_max_value` as well. Defaults to 0, logging all entries. |
| Also see `Log File Formats`_. |
| |
| .. option:: log_hist_msec=int |
| |
| Same as :option:`log_avg_msec`, but logs entries for completion latency |
| histograms. Computing latency percentiles from averages of intervals using |
| :option:`log_avg_msec` is inaccurate. Setting this option makes fio log |
| histogram entries over the specified period of time, reducing log sizes for |
| high IOPS devices while retaining percentile accuracy. See |
| :option:`log_hist_coarseness` and :option:`write_hist_log` as well. |
| Defaults to 0, meaning histogram logging is disabled. |
| |
| .. option:: log_hist_coarseness=int |
| |
| Integer ranging from 0 to 6, defining the coarseness of the resolution of |
| the histogram logs enabled with :option:`log_hist_msec`. For each increment |
| in coarseness, fio outputs half as many bins. Defaults to 0, for which |
| histogram logs contain 1216 latency bins. See :option:`write_hist_log` |
| and `Log File Formats`_. |
| |
| .. option:: log_max_value=bool |
| |
| If :option:`log_avg_msec` is set, fio logs the average over that window. If |
| you instead want to log the maximum value, set this option to 1. Defaults to |
| 0, meaning that averaged values are logged. |
| |
| .. option:: log_offset=bool |
| |
| If this is set, the iolog options will include the byte offset for the I/O |
| entry as well as the other data values. Defaults to 0 meaning that |
| offsets are not present in logs. Also see `Log File Formats`_. |
| |
| .. option:: log_compression=int |
| |
| If this is set, fio will compress the I/O logs as it goes, to keep the |
| memory footprint lower. When a log reaches the specified size, that chunk is |
| removed and compressed in the background. Given that I/O logs are fairly |
| highly compressible, this yields a nice memory savings for longer runs. The |
| downside is that the compression will consume some background CPU cycles, so |
| it may impact the run. This, however, is also true if the logging ends up |
| consuming most of the system memory. So pick your poison. The I/O logs are |
| saved normally at the end of a run, by decompressing the chunks and storing |
| them in the specified log file. This feature depends on the availability of |
| zlib. |
| |
| .. option:: log_compression_cpus=str |
| |
| Define the set of CPUs that are allowed to handle online log compression for |
| the I/O jobs. This can provide better isolation between performance |
| sensitive jobs, and background compression work. See |
| :option:`cpus_allowed` for the format used. |
| |
| .. option:: log_store_compressed=bool |
| |
| If set, fio will store the log files in a compressed format. They can be |
| decompressed with fio, using the :option:`--inflate-log` command line |
| parameter. The files will be stored with a :file:`.fz` suffix. |
| |
| .. option:: log_unix_epoch=bool |
| |
| If set, fio will log Unix timestamps to the log files produced by enabling |
| write_type_log for each log type, instead of the default zero-based |
| timestamps. |
| |
| .. option:: block_error_percentiles=bool |
| |
| If set, record errors in trim block-sized units from writes and trims and |
| output a histogram of how many trims it took to get to errors, and what kind |
| of error was encountered. |
| |
| .. option:: bwavgtime=int |
| |
| Average the calculated bandwidth over the given time. Value is specified in |
| milliseconds. If the job also does bandwidth logging through |
| :option:`write_bw_log`, then the minimum of this option and |
| :option:`log_avg_msec` will be used. Default: 500ms. |
| |
| .. option:: iopsavgtime=int |
| |
| Average the calculated IOPS over the given time. Value is specified in |
| milliseconds. If the job also does IOPS logging through |
| :option:`write_iops_log`, then the minimum of this option and |
| :option:`log_avg_msec` will be used. Default: 500ms. |
| |
| .. option:: disk_util=bool |
| |
| Generate disk utilization statistics, if the platform supports it. |
| Default: true. |
| |
| .. option:: disable_lat=bool |
| |
| Disable measurements of total latency numbers. Useful only for cutting back |
| the number of calls to :manpage:`gettimeofday(2)`, as that does impact |
| performance at really high IOPS rates. Note that to really get rid of a |
| large amount of these calls, this option must be used with |
| :option:`disable_slat` and :option:`disable_bw_measurement` as well. |
| |
| .. option:: disable_clat=bool |
| |
| Disable measurements of completion latency numbers. See |
| :option:`disable_lat`. |
| |
| .. option:: disable_slat=bool |
| |
| Disable measurements of submission latency numbers. See |
| :option:`disable_lat`. |
| |
| .. option:: disable_bw_measurement=bool, disable_bw=bool |
| |
| Disable measurements of throughput/bandwidth numbers. See |
| :option:`disable_lat`. |
| |
| .. option:: slat_percentiles=bool |
| |
| Report submission latency percentiles. Submission latency is not recorded |
| for synchronous ioengines. |
| |
| .. option:: clat_percentiles=bool |
| |
| Report completion latency percentiles. |
| |
| .. option:: lat_percentiles=bool |
| |
| Report total latency percentiles. Total latency is the sum of submission |
| latency and completion latency. |
| |
| .. option:: percentile_list=float_list |
| |
| Overwrite the default list of percentiles for latencies and the block error |
| histogram. Each number is a floating point number in the range (0,100], and |
| the maximum length of the list is 20. Use ``:`` to separate the numbers. For |
| example, ``--percentile_list=99.5:99.9`` will cause fio to report the |
| latency durations below which 99.5% and 99.9% of the observed latencies fell, |
| respectively. |
| |
| .. option:: significant_figures=int |
| |
| If using :option:`--output-format` of `normal`, set the significant |
| figures to this value. Higher values will yield more precise IOPS and |
| throughput units, while lower values will round. Requires a minimum |
| value of 1 and a maximum value of 10. Defaults to 4. |
| |
| |
| Error handling |
| ~~~~~~~~~~~~~~ |
| |
| .. option:: exitall_on_error |
| |
| When one job finishes in error, terminate the rest. The default is to wait |
| for each job to finish. |
| |
| .. option:: continue_on_error=str |
| |
| Normally fio will exit the job on the first observed failure. If this option |
| is set, fio will continue the job when there is a 'non-fatal error' (EIO or |
| EILSEQ) until the runtime is exceeded or the I/O size specified is |
| completed. If this option is used, there are two more stats that are |
| appended, the total error count and the first error. The error field given |
| in the stats is the first error that was hit during the run. |
| |
| The allowed values are: |
| |
| **none** |
| Exit on any I/O or verify errors. |
| |
| **read** |
| Continue on read errors, exit on all others. |
| |
| **write** |
| Continue on write errors, exit on all others. |
| |
| **io** |
| Continue on any I/O error, exit on all others. |
| |
| **verify** |
| Continue on verify errors, exit on all others. |
| |
| **all** |
| Continue on all errors. |
| |
| **0** |
| Backward-compatible alias for 'none'. |
| |
| **1** |
| Backward-compatible alias for 'all'. |
| |
| .. option:: ignore_error=str |
| |
| Sometimes you want to ignore some errors during test in that case you can |
| specify error list for each error type, instead of only being able to |
| ignore the default 'non-fatal error' using :option:`continue_on_error`. |
| ``ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST`` errors for |
| given error type is separated with ':'. Error may be symbol ('ENOSPC', |
| 'ENOMEM') or integer. Example:: |
| |
| ignore_error=EAGAIN,ENOSPC:122 |
| |
| This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from |
| WRITE. This option works by overriding :option:`continue_on_error` with |
| the list of errors for each error type if any. |
| |
| .. option:: error_dump=bool |
| |
| If set dump every error even if it is non fatal, true by default. If |
| disabled only fatal error will be dumped. |
| |
| Running predefined workloads |
| ---------------------------- |
| |
| Fio includes predefined profiles that mimic the I/O workloads generated by |
| other tools. |
| |
| .. option:: profile=str |
| |
| The predefined workload to run. Current profiles are: |
| |
| **tiobench** |
| Threaded I/O bench (tiotest/tiobench) like workload. |
| |
| **act** |
| Aerospike Certification Tool (ACT) like workload. |
| |
| To view a profile's additional options use :option:`--cmdhelp` after specifying |
| the profile. For example:: |
| |
| $ fio --profile=act --cmdhelp |
| |
| Act profile options |
| ~~~~~~~~~~~~~~~~~~~ |
| |
| .. option:: device-names=str |
| :noindex: |
| |
| Devices to use. |
| |
| .. option:: load=int |
| :noindex: |
| |
| ACT load multiplier. Default: 1. |
| |
| .. option:: test-duration=time |
| :noindex: |
| |
| How long the entire test takes to run. When the unit is omitted, the value |
| is given in seconds. Default: 24h. |
| |
| .. option:: threads-per-queue=int |
| :noindex: |
| |
| Number of read I/O threads per device. Default: 8. |
| |
| .. option:: read-req-num-512-blocks=int |
| :noindex: |
| |
| Number of 512B blocks to read at the time. Default: 3. |
| |
| .. option:: large-block-op-kbytes=int |
| :noindex: |
| |
| Size of large block ops in KiB (writes). Default: 131072. |
| |
| .. option:: prep |
| :noindex: |
| |
| Set to run ACT prep phase. |
| |
| Tiobench profile options |
| ~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| .. option:: size=str |
| :noindex: |
| |
| Size in MiB. |
| |
| .. option:: block=int |
| :noindex: |
| |
| Block size in bytes. Default: 4096. |
| |
| .. option:: numruns=int |
| :noindex: |
| |
| Number of runs. |
| |
| .. option:: dir=str |
| :noindex: |
| |
| Test directory. |
| |
| .. option:: threads=int |
| :noindex: |
| |
| Number of threads. |
| |
| Interpreting the output |
| ----------------------- |
| |
| .. |
| Example output was based on the following: |
| TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --time_based \ |
| --rate=1256k --bs=14K --name=quick --runtime=1s --name=mixed \ |
| --runtime=2m --rw=rw |
| |
| Fio spits out a lot of output. While running, fio will display the status of the |
| jobs created. An example of that would be:: |
| |
| Jobs: 1 (f=1): [_(1),M(1)][24.8%][r=20.5MiB/s,w=23.5MiB/s][r=82,w=94 IOPS][eta 01m:31s] |
| |
| The characters inside the first set of square brackets denote the current status of |
| each thread. The first character is the first job defined in the job file, and so |
| forth. The possible values (in typical life cycle order) are: |
| |
| +------+-----+-----------------------------------------------------------+ |
| | Idle | Run | | |
| +======+=====+===========================================================+ |
| | P | | Thread setup, but not started. | |
| +------+-----+-----------------------------------------------------------+ |
| | C | | Thread created. | |
| +------+-----+-----------------------------------------------------------+ |
| | I | | Thread initialized, waiting or generating necessary data. | |
| +------+-----+-----------------------------------------------------------+ |
| | | p | Thread running pre-reading file(s). | |
| +------+-----+-----------------------------------------------------------+ |
| | | / | Thread is in ramp period. | |
| +------+-----+-----------------------------------------------------------+ |
| | | R | Running, doing sequential reads. | |
| +------+-----+-----------------------------------------------------------+ |
| | | r | Running, doing random reads. | |
| +------+-----+-----------------------------------------------------------+ |
| | | W | Running, doing sequential writes. | |
| +------+-----+-----------------------------------------------------------+ |
| | | w | Running, doing random writes. | |
| +------+-----+-----------------------------------------------------------+ |
| | | M | Running, doing mixed sequential reads/writes. | |
| +------+-----+-----------------------------------------------------------+ |
| | | m | Running, doing mixed random reads/writes. | |
| +------+-----+-----------------------------------------------------------+ |
| | | D | Running, doing sequential trims. | |
| +------+-----+-----------------------------------------------------------+ |
| | | d | Running, doing random trims. | |
| +------+-----+-----------------------------------------------------------+ |
| | | F | Running, currently waiting for :manpage:`fsync(2)`. | |
| +------+-----+-----------------------------------------------------------+ |
| | | V | Running, doing verification of written data. | |
| +------+-----+-----------------------------------------------------------+ |
| | f | | Thread finishing. | |
| +------+-----+-----------------------------------------------------------+ |
| | E | | Thread exited, not reaped by main thread yet. | |
| +------+-----+-----------------------------------------------------------+ |
| | _ | | Thread reaped. | |
| +------+-----+-----------------------------------------------------------+ |
| | X | | Thread reaped, exited with an error. | |
| +------+-----+-----------------------------------------------------------+ |
| | K | | Thread reaped, exited due to signal. | |
| +------+-----+-----------------------------------------------------------+ |
| |
| .. |
| Example output was based on the following: |
| TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --runtime=58m \ |
| --time_based --rate=2512k --bs=256K --numjobs=10 \ |
| --name=readers --rw=read --name=writers --rw=write |
| |
| Fio will condense the thread string as not to take up more space on the command |
| line than needed. For instance, if you have 10 readers and 10 writers running, |
| the output would look like this:: |
| |
| Jobs: 20 (f=20): [R(10),W(10)][4.0%][r=20.5MiB/s,w=23.5MiB/s][r=82,w=94 IOPS][eta 57m:36s] |
| |
| Note that the status string is displayed in order, so it's possible to tell which of |
| the jobs are currently doing what. In the example above this means that jobs 1--10 |
| are readers and 11--20 are writers. |
| |
| The other values are fairly self explanatory -- number of threads currently |
| running and doing I/O, the number of currently open files (f=), the estimated |
| completion percentage, the rate of I/O since last check (read speed listed first, |
| then write speed and optionally trim speed) in terms of bandwidth and IOPS, |
| and time to completion for the current running group. It's impossible to estimate |
| runtime of the following groups (if any). |
| |
| .. |
| Example output was based on the following: |
| TZ=UTC fio --iodepth=16 --ioengine=posixaio --filename=/tmp/fiofile \ |
| --direct=1 --size=100M --time_based --runtime=50s --rate_iops=89 \ |
| --bs=7K --name=Client1 --rw=write |
| |
| When fio is done (or interrupted by :kbd:`Ctrl-C`), it will show the data for |
| each thread, group of threads, and disks in that order. For each overall thread (or |
| group) the output looks like:: |
| |
| Client1: (groupid=0, jobs=1): err= 0: pid=16109: Sat Jun 24 12:07:54 2017 |
| write: IOPS=88, BW=623KiB/s (638kB/s)(30.4MiB/50032msec) |
| slat (nsec): min=500, max=145500, avg=8318.00, stdev=4781.50 |
| clat (usec): min=170, max=78367, avg=4019.02, stdev=8293.31 |
| lat (usec): min=174, max=78375, avg=4027.34, stdev=8291.79 |
| clat percentiles (usec): |
| | 1.00th=[ 302], 5.00th=[ 326], 10.00th=[ 343], 20.00th=[ 363], |
| | 30.00th=[ 392], 40.00th=[ 404], 50.00th=[ 416], 60.00th=[ 445], |
| | 70.00th=[ 816], 80.00th=[ 6718], 90.00th=[12911], 95.00th=[21627], |
| | 99.00th=[43779], 99.50th=[51643], 99.90th=[68682], 99.95th=[72877], |
| | 99.99th=[78119] |
| bw ( KiB/s): min= 532, max= 686, per=0.10%, avg=622.87, stdev=24.82, samples= 100 |
| iops : min= 76, max= 98, avg=88.98, stdev= 3.54, samples= 100 |
| lat (usec) : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79% |
| lat (msec) : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37% |
| lat (msec) : 100=0.65% |
| cpu : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21 |
| IO depths : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0% |
| submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% |
| complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% |
| issued rwt: total=0,4450,0, short=0,0,0, dropped=0,0,0 |
| latency : target=0, window=0, percentile=100.00%, depth=8 |
| |
| The job name (or first job's name when using :option:`group_reporting`) is printed, |
| along with the group id, count of jobs being aggregated, last error id seen (which |
| is 0 when there are no errors), pid/tid of that thread and the time the job/group |
| completed. Below are the I/O statistics for each data direction performed (showing |
| writes in the example above). In the order listed, they denote: |
| |
| **read/write/trim** |
| The string before the colon shows the I/O direction the statistics |
| are for. **IOPS** is the average I/Os performed per second. **BW** |
| is the average bandwidth rate shown as: value in power of 2 format |
| (value in power of 10 format). The last two values show: (**total |
| I/O performed** in power of 2 format / **runtime** of that thread). |
| |
| **slat** |
| Submission latency (**min** being the minimum, **max** being the |
| maximum, **avg** being the average, **stdev** being the standard |
| deviation). This is the time it took to submit the I/O. For |
| sync I/O this row is not displayed as the slat is really the |
| completion latency (since queue/complete is one operation there). |
| This value can be in nanoseconds, microseconds or milliseconds --- |
| fio will choose the most appropriate base and print that (in the |
| example above nanoseconds was the best scale). Note: in :option:`--minimal` mode |
| latencies are always expressed in microseconds. |
| |
| **clat** |
| Completion latency. Same names as slat, this denotes the time from |
| submission to completion of the I/O pieces. For sync I/O, clat will |
| usually be equal (or very close) to 0, as the time from submit to |
| complete is basically just CPU time (I/O has already been done, see slat |
| explanation). |
| |
| **lat** |
| Total latency. Same names as slat and clat, this denotes the time from |
| when fio created the I/O unit to completion of the I/O operation. |
| |
| **bw** |
| Bandwidth statistics based on samples. Same names as the xlat stats, |
| but also includes the number of samples taken (**samples**) and an |
| approximate percentage of total aggregate bandwidth this thread |
| received in its group (**per**). This last value is only really |
| useful if the threads in this group are on the same disk, since they |
| are then competing for disk access. |
| |
| **iops** |
| IOPS statistics based on samples. Same names as bw. |
| |
| **lat (nsec/usec/msec)** |
| The distribution of I/O completion latencies. This is the time from when |
| I/O leaves fio and when it gets completed. Unlike the separate |
| read/write/trim sections above, the data here and in the remaining |
| sections apply to all I/Os for the reporting group. 250=0.04% means that |
| 0.04% of the I/Os completed in under 250us. 500=64.11% means that 64.11% |
| of the I/Os required 250 to 499us for completion. |
| |
| **cpu** |
| CPU usage. User and system time, along with the number of context |
| switches this thread went through, usage of system and user time, and |
| finally the number of major and minor page faults. The CPU utilization |
| numbers are averages for the jobs in that reporting group, while the |
| context and fault counters are summed. |
| |
| **IO depths** |
| The distribution of I/O depths over the job lifetime. The numbers are |
| divided into powers of 2 and each entry covers depths from that value |
| up to those that are lower than the next entry -- e.g., 16= covers |
| depths from 16 to 31. Note that the range covered by a depth |
| distribution entry can be different to the range covered by the |
| equivalent submit/complete distribution entry. |
| |
| **IO submit** |
| How many pieces of I/O were submitting in a single submit call. Each |
| entry denotes that amount and below, until the previous entry -- e.g., |
| 16=100% means that we submitted anywhere between 9 to 16 I/Os per submit |
| call. Note that the range covered by a submit distribution entry can |
| be different to the range covered by the equivalent depth distribution |
| entry. |
| |
| **IO complete** |
| Like the above submit number, but for completions instead. |
| |
| **IO issued rwt** |
| The number of read/write/trim requests issued, and how many of them were |
| short or dropped. |
| |
| **IO latency** |
| These values are for :option:`latency_target` and related options. When |
| these options are engaged, this section describes the I/O depth required |
| to meet the specified latency target. |
| |
| .. |
| Example output was based on the following: |
| TZ=UTC fio --ioengine=null --iodepth=2 --size=100M --numjobs=2 \ |
| --rate_process=poisson --io_limit=32M --name=read --bs=128k \ |
| --rate=11M --name=write --rw=write --bs=2k --rate=700k |
| |
| After each client has been listed, the group statistics are printed. They |
| will look like this:: |
| |
| Run status group 0 (all jobs): |
| READ: bw=20.9MiB/s (21.9MB/s), 10.4MiB/s-10.8MiB/s (10.9MB/s-11.3MB/s), io=64.0MiB (67.1MB), run=2973-3069msec |
| WRITE: bw=1231KiB/s (1261kB/s), 616KiB/s-621KiB/s (630kB/s-636kB/s), io=64.0MiB (67.1MB), run=52747-53223msec |
| |
| For each data direction it prints: |
| |
| **bw** |
| Aggregate bandwidth of threads in this group followed by the |
| minimum and maximum bandwidth of all the threads in this group. |
| Values outside of brackets are power-of-2 format and those |
| within are the equivalent value in a power-of-10 format. |
| **io** |
| Aggregate I/O performed of all threads in this group. The |
| format is the same as bw. |
| **run** |
| The smallest and longest runtimes of the threads in this group. |
| |
| And finally, the disk statistics are printed. This is Linux specific. They will look like this:: |
| |
| Disk stats (read/write): |
| sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00% |
| |
| Each value is printed for both reads and writes, with reads first. The |
| numbers denote: |
| |
| **ios** |
| Number of I/Os performed by all groups. |
| **merge** |
| Number of merges performed by the I/O scheduler. |
| **ticks** |
| Number of ticks we kept the disk busy. |
| **in_queue** |
| Total time spent in the disk queue. |
| **util** |
| The disk utilization. A value of 100% means we kept the disk |
| busy constantly, 50% would be a disk idling half of the time. |
| |
| It is also possible to get fio to dump the current output while it is running, |
| without terminating the job. To do that, send fio the **USR1** signal. You can |
| also get regularly timed dumps by using the :option:`--status-interval` |
| parameter, or by creating a file in :file:`/tmp` named |
| :file:`fio-dump-status`. If fio sees this file, it will unlink it and dump the |
| current output status. |
| |
| |
| Terse output |
| ------------ |
| |
| For scripted usage where you typically want to generate tables or graphs of the |
| results, fio can output the results in a semicolon separated format. The format |
| is one long line of values, such as:: |
| |
| 2;card0;0;0;7139336;121836;60004;1;10109;27.932460;116.933948;220;126861;3495.446807;1085.368601;226;126864;3523.635629;1089.012448;24063;99944;50.275485%;59818.274627;5540.657370;7155060;122104;60004;1;8338;29.086342;117.839068;388;128077;5032.488518;1234.785715;391;128085;5061.839412;1236.909129;23436;100928;50.287926%;59964.832030;5644.844189;14.595833%;19.394167%;123706;0;7313;0.1%;0.1%;0.1%;0.1%;0.1%;0.1%;100.0%;0.00%;0.00%;0.00%;0.00%;0.00%;0.00%;0.01%;0.02%;0.05%;0.16%;6.04%;40.40%;52.68%;0.64%;0.01%;0.00%;0.01%;0.00%;0.00%;0.00%;0.00%;0.00% |
| A description of this job goes here. |
| |
| The job description (if provided) follows on a second line for terse v2. |
| It appears on the same line for other terse versions. |
| |
| To enable terse output, use the :option:`--minimal` or |
| :option:`--output-format`\=terse command line options. The |
| first value is the version of the terse output format. If the output has to be |
| changed for some reason, this number will be incremented by 1 to signify that |
| change. |
| |
| Split up, the format is as follows (comments in brackets denote when a |
| field was introduced or whether it's specific to some terse version): |
| |
| :: |
| |
| terse version, fio version [v3], jobname, groupid, error |
| |
| READ status:: |
| |
| Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec) |
| Submission latency: min, max, mean, stdev (usec) |
| Completion latency: min, max, mean, stdev (usec) |
| Completion latency percentiles: 20 fields (see below) |
| Total latency: min, max, mean, stdev (usec) |
| Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5] |
| IOPS [v5]: min, max, mean, stdev, number of samples |
| |
| WRITE status: |
| |
| :: |
| |
| Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec) |
| Submission latency: min, max, mean, stdev (usec) |
| Completion latency: min, max, mean, stdev (usec) |
| Completion latency percentiles: 20 fields (see below) |
| Total latency: min, max, mean, stdev (usec) |
| Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5] |
| IOPS [v5]: min, max, mean, stdev, number of samples |
| |
| TRIM status [all but version 3]: |
| |
| Fields are similar to READ/WRITE status. |
| |
| CPU usage:: |
| |
| user, system, context switches, major faults, minor faults |
| |
| I/O depths:: |
| |
| <=1, 2, 4, 8, 16, 32, >=64 |
| |
| I/O latencies microseconds:: |
| |
| <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000 |
| |
| I/O latencies milliseconds:: |
| |
| <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000 |
| |
| Disk utilization [v3]:: |
| |
| disk name, read ios, write ios, read merges, write merges, read ticks, write ticks, |
| time spent in queue, disk utilization percentage |
| |
| Additional Info (dependent on continue_on_error, default off):: |
| |
| total # errors, first error code |
| |
| Additional Info (dependent on description being set):: |
| |
| Text description |
| |
| Completion latency percentiles can be a grouping of up to 20 sets, so for the |
| terse output fio writes all of them. Each field will look like this:: |
| |
| 1.00%=6112 |
| |
| which is the Xth percentile, and the `usec` latency associated with it. |
| |
| For `Disk utilization`, all disks used by fio are shown. So for each disk there |
| will be a disk utilization section. |
| |
| Below is a single line containing short names for each of the fields in the |
| minimal output v3, separated by semicolons:: |
| |
| terse_version_3;fio_version;jobname;groupid;error;read_kb;read_bandwidth_kb;read_iops;read_runtime_ms;read_slat_min_us;read_slat_max_us;read_slat_mean_us;read_slat_dev_us;read_clat_min_us;read_clat_max_us;read_clat_mean_us;read_clat_dev_us;read_clat_pct01;read_clat_pct02;read_clat_pct03;read_clat_pct04;read_clat_pct05;read_clat_pct06;read_clat_pct07;read_clat_pct08;read_clat_pct09;read_clat_pct10;read_clat_pct11;read_clat_pct12;read_clat_pct13;read_clat_pct14;read_clat_pct15;read_clat_pct16;read_clat_pct17;read_clat_pct18;read_clat_pct19;read_clat_pct20;read_tlat_min_us;read_lat_max_us;read_lat_mean_us;read_lat_dev_us;read_bw_min_kb;read_bw_max_kb;read_bw_agg_pct;read_bw_mean_kb;read_bw_dev_kb;write_kb;write_bandwidth_kb;write_iops;write_runtime_ms;write_slat_min_us;write_slat_max_us;write_slat_mean_us;write_slat_dev_us;write_clat_min_us;write_clat_max_us;write_clat_mean_us;write_clat_dev_us;write_clat_pct01;write_clat_pct02;write_clat_pct03;write_clat_pct04;write_clat_pct05;write_clat_pct06;write_clat_pct07;write_clat_pct08;write_clat_pct09;write_clat_pct10;write_clat_pct11;write_clat_pct12;write_clat_pct13;write_clat_pct14;write_clat_pct15;write_clat_pct16;write_clat_pct17;write_clat_pct18;write_clat_pct19;write_clat_pct20;write_tlat_min_us;write_lat_max_us;write_lat_mean_us;write_lat_dev_us;write_bw_min_kb;write_bw_max_kb;write_bw_agg_pct;write_bw_mean_kb;write_bw_dev_kb;cpu_user;cpu_sys;cpu_csw;cpu_mjf;cpu_minf;iodepth_1;iodepth_2;iodepth_4;iodepth_8;iodepth_16;iodepth_32;iodepth_64;lat_2us;lat_4us;lat_10us;lat_20us;lat_50us;lat_100us;lat_250us;lat_500us;lat_750us;lat_1000us;lat_2ms;lat_4ms;lat_10ms;lat_20ms;lat_50ms;lat_100ms;lat_250ms;lat_500ms;lat_750ms;lat_1000ms;lat_2000ms;lat_over_2000ms;disk_name;disk_read_iops;disk_write_iops;disk_read_merges;disk_write_merges;disk_read_ticks;write_ticks;disk_queue_time;disk_util |
| |
| In client/server mode terse output differs from what appears when jobs are run |
| locally. Disk utilization data is omitted from the standard terse output and |
| for v3 and later appears on its own separate line at the end of each terse |
| reporting cycle. |
| |
| |
| JSON output |
| ------------ |
| |
| The `json` output format is intended to be both human readable and convenient |
| for automated parsing. For the most part its sections mirror those of the |
| `normal` output. The `runtime` value is reported in msec and the `bw` value is |
| reported in 1024 bytes per second units. |
| |
| |
| JSON+ output |
| ------------ |
| |
| The `json+` output format is identical to the `json` output format except that it |
| adds a full dump of the completion latency bins. Each `bins` object contains a |
| set of (key, value) pairs where keys are latency durations and values count how |
| many I/Os had completion latencies of the corresponding duration. For example, |
| consider: |
| |
| "bins" : { "87552" : 1, "89600" : 1, "94720" : 1, "96768" : 1, "97792" : 1, "99840" : 1, "100864" : 2, "103936" : 6, "104960" : 534, "105984" : 5995, "107008" : 7529, ... } |
| |
| This data indicates that one I/O required 87,552ns to complete, two I/Os required |
| 100,864ns to complete, and 7529 I/Os required 107,008ns to complete. |
| |
| Also included with fio is a Python script `fio_jsonplus_clat2csv` that takes |
| json+ output and generates CSV-formatted latency data suitable for plotting. |
| |
| The latency durations actually represent the midpoints of latency intervals. |
| For details refer to :file:`stat.h`. |
| |
| |
| Trace file format |
| ----------------- |
| |
| There are two trace file format that you can encounter. The older (v1) format is |
| unsupported since version 1.20-rc3 (March 2008). It will still be described |
| below in case that you get an old trace and want to understand it. |
| |
| In any case the trace is a simple text file with a single action per line. |
| |
| |
| Trace file format v1 |
| ~~~~~~~~~~~~~~~~~~~~ |
| |
| Each line represents a single I/O action in the following format:: |
| |
| rw, offset, length |
| |
| where `rw=0/1` for read/write, and the `offset` and `length` entries being in bytes. |
| |
| This format is not supported in fio versions >= 1.20-rc3. |
| |
| |
| Trace file format v2 |
| ~~~~~~~~~~~~~~~~~~~~ |
| |
| The second version of the trace file format was added in fio version 1.17. It |
| allows to access more then one file per trace and has a bigger set of possible |
| file actions. |
| |
| The first line of the trace file has to be:: |
| |
| fio version 2 iolog |
| |
| Following this can be lines in two different formats, which are described below. |
| |
| The file management format:: |
| |
| filename action |
| |
| The `filename` is given as an absolute path. The `action` can be one of these: |
| |
| **add** |
| Add the given `filename` to the trace. |
| **open** |
| Open the file with the given `filename`. The `filename` has to have |
| been added with the **add** action before. |
| **close** |
| Close the file with the given `filename`. The file has to have been |
| opened before. |
| |
| |
| The file I/O action format:: |
| |
| filename action offset length |
| |
| The `filename` is given as an absolute path, and has to have been added and |
| opened before it can be used with this format. The `offset` and `length` are |
| given in bytes. The `action` can be one of these: |
| |
| **wait** |
| Wait for `offset` microseconds. Everything below 100 is discarded. |
| The time is relative to the previous `wait` statement. |
| **read** |
| Read `length` bytes beginning from `offset`. |
| **write** |
| Write `length` bytes beginning from `offset`. |
| **sync** |
| :manpage:`fsync(2)` the file. |
| **datasync** |
| :manpage:`fdatasync(2)` the file. |
| **trim** |
| Trim the given file from the given `offset` for `length` bytes. |
| |
| |
| I/O Replay - Merging Traces |
| --------------------------- |
| |
| Colocation is a common practice used to get the most out of a machine. |
| Knowing which workloads play nicely with each other and which ones don't is |
| a much harder task. While fio can replay workloads concurrently via multiple |
| jobs, it leaves some variability up to the scheduler making results harder to |
| reproduce. Merging is a way to make the order of events consistent. |
| |
| Merging is integrated into I/O replay and done when a |
| :option:`merge_blktrace_file` is specified. The list of files passed to |
| :option:`read_iolog` go through the merge process and output a single file |
| stored to the specified file. The output file is passed on as if it were the |
| only file passed to :option:`read_iolog`. An example would look like:: |
| |
| $ fio --read_iolog="<file1>:<file2>" --merge_blktrace_file="<output_file>" |
| |
| Creating only the merged file can be done by passing the command line argument |
| :option:`--merge-blktrace-only`. |
| |
| Scaling traces can be done to see the relative impact of any particular trace |
| being slowed down or sped up. :option:`merge_blktrace_scalars` takes in a colon |
| separated list of percentage scalars. It is index paired with the files passed |
| to :option:`read_iolog`. |
| |
| With scaling, it may be desirable to match the running time of all traces. |
| This can be done with :option:`merge_blktrace_iters`. It is index paired with |
| :option:`read_iolog` just like :option:`merge_blktrace_scalars`. |
| |
| In an example, given two traces, A and B, each 60s long. If we want to see |
| the impact of trace A issuing IOs twice as fast and repeat trace A over the |
| runtime of trace B, the following can be done:: |
| |
| $ fio --read_iolog="<trace_a>:"<trace_b>" --merge_blktrace_file"<output_file>" --merge_blktrace_scalars="50:100" --merge_blktrace_iters="2:1" |
| |
| This runs trace A at 2x the speed twice for approximately the same runtime as |
| a single run of trace B. |
| |
| |
| CPU idleness profiling |
| ---------------------- |
| |
| In some cases, we want to understand CPU overhead in a test. For example, we |
| test patches for the specific goodness of whether they reduce CPU usage. |
| Fio implements a balloon approach to create a thread per CPU that runs at idle |
| priority, meaning that it only runs when nobody else needs the cpu. |
| By measuring the amount of work completed by the thread, idleness of each CPU |
| can be derived accordingly. |
| |
| An unit work is defined as touching a full page of unsigned characters. Mean and |
| standard deviation of time to complete an unit work is reported in "unit work" |
| section. Options can be chosen to report detailed percpu idleness or overall |
| system idleness by aggregating percpu stats. |
| |
| |
| Verification and triggers |
| ------------------------- |
| |
| Fio is usually run in one of two ways, when data verification is done. The first |
| is a normal write job of some sort with verify enabled. When the write phase has |
| completed, fio switches to reads and verifies everything it wrote. The second |
| model is running just the write phase, and then later on running the same job |
| (but with reads instead of writes) to repeat the same I/O patterns and verify |
| the contents. Both of these methods depend on the write phase being completed, |
| as fio otherwise has no idea how much data was written. |
| |
| With verification triggers, fio supports dumping the current write state to |
| local files. Then a subsequent read verify workload can load this state and know |
| exactly where to stop. This is useful for testing cases where power is cut to a |
| server in a managed fashion, for instance. |
| |
| A verification trigger consists of two things: |
| |
| 1) Storing the write state of each job. |
| 2) Executing a trigger command. |
| |
| The write state is relatively small, on the order of hundreds of bytes to single |
| kilobytes. It contains information on the number of completions done, the last X |
| completions, etc. |
| |
| A trigger is invoked either through creation ('touch') of a specified file in |
| the system, or through a timeout setting. If fio is run with |
| :option:`--trigger-file`\= :file:`/tmp/trigger-file`, then it will continually |
| check for the existence of :file:`/tmp/trigger-file`. When it sees this file, it |
| will fire off the trigger (thus saving state, and executing the trigger |
| command). |
| |
| For client/server runs, there's both a local and remote trigger. If fio is |
| running as a server backend, it will send the job states back to the client for |
| safe storage, then execute the remote trigger, if specified. If a local trigger |
| is specified, the server will still send back the write state, but the client |
| will then execute the trigger. |
| |
| Verification trigger example |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| Let's say we want to run a powercut test on the remote Linux machine 'server'. |
| Our write workload is in :file:`write-test.fio`. We want to cut power to 'server' at |
| some point during the run, and we'll run this test from the safety or our local |
| machine, 'localbox'. On the server, we'll start the fio backend normally:: |
| |
| server# fio --server |
| |
| and on the client, we'll fire off the workload:: |
| |
| localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\"" |
| |
| We set :file:`/tmp/my-trigger` as the trigger file, and we tell fio to execute:: |
| |
| echo b > /proc/sysrq-trigger |
| |
| on the server once it has received the trigger and sent us the write state. This |
| will work, but it's not **really** cutting power to the server, it's merely |
| abruptly rebooting it. If we have a remote way of cutting power to the server |
| through IPMI or similar, we could do that through a local trigger command |
| instead. Let's assume we have a script that does IPMI reboot of a given hostname, |
| ipmi-reboot. On localbox, we could then have run fio with a local trigger |
| instead:: |
| |
| localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server" |
| |
| For this case, fio would wait for the server to send us the write state, then |
| execute ``ipmi-reboot server`` when that happened. |
| |
| Loading verify state |
| ~~~~~~~~~~~~~~~~~~~~ |
| |
| To load stored write state, a read verification job file must contain the |
| :option:`verify_state_load` option. If that is set, fio will load the previously |
| stored state. For a local fio run this is done by loading the files directly, |
| and on a client/server run, the server backend will ask the client to send the |
| files over and load them from there. |
| |
| |
| Log File Formats |
| ---------------- |
| |
| Fio supports a variety of log file formats, for logging latencies, bandwidth, |
| and IOPS. The logs share a common format, which looks like this: |
| |
| *time* (`msec`), *value*, *data direction*, *block size* (`bytes`), |
| *offset* (`bytes`), *command priority* |
| |
| *Time* for the log entry is always in milliseconds. The *value* logged depends |
| on the type of log, it will be one of the following: |
| |
| **Latency log** |
| Value is latency in nsecs |
| **Bandwidth log** |
| Value is in KiB/sec |
| **IOPS log** |
| Value is IOPS |
| |
| *Data direction* is one of the following: |
| |
| **0** |
| I/O is a READ |
| **1** |
| I/O is a WRITE |
| **2** |
| I/O is a TRIM |
| |
| The entry's *block size* is always in bytes. The *offset* is the position in bytes |
| from the start of the file for that particular I/O. The logging of the offset can be |
| toggled with :option:`log_offset`. |
| |
| *Command priority* is 0 for normal priority and 1 for high priority. This is controlled |
| by the ioengine specific :option:`cmdprio_percentage`. |
| |
| Fio defaults to logging every individual I/O but when windowed logging is set |
| through :option:`log_avg_msec`, either the average (by default) or the maximum |
| (:option:`log_max_value` is set) *value* seen over the specified period of time |
| is recorded. Each *data direction* seen within the window period will aggregate |
| its values in a separate row. Further, when using windowed logging the *block |
| size* and *offset* entries will always contain 0. |
| |
| |
| Client/Server |
| ------------- |
| |
| Normally fio is invoked as a stand-alone application on the machine where the |
| I/O workload should be generated. However, the backend and frontend of fio can |
| be run separately i.e., the fio server can generate an I/O workload on the "Device |
| Under Test" while being controlled by a client on another machine. |
| |
| Start the server on the machine which has access to the storage DUT:: |
| |
| $ fio --server=args |
| |
| where `args` defines what fio listens to. The arguments are of the form |
| ``type,hostname`` or ``IP,port``. *type* is either ``ip`` (or ip4) for TCP/IP |
| v4, ``ip6`` for TCP/IP v6, or ``sock`` for a local unix domain socket. |
| *hostname* is either a hostname or IP address, and *port* is the port to listen |
| to (only valid for TCP/IP, not a local socket). Some examples: |
| |
| 1) ``fio --server`` |
| |
| Start a fio server, listening on all interfaces on the default port (8765). |
| |
| 2) ``fio --server=ip:hostname,4444`` |
| |
| Start a fio server, listening on IP belonging to hostname and on port 4444. |
| |
| 3) ``fio --server=ip6:::1,4444`` |
| |
| Start a fio server, listening on IPv6 localhost ::1 and on port 4444. |
| |
| 4) ``fio --server=,4444`` |
| |
| Start a fio server, listening on all interfaces on port 4444. |
| |
| 5) ``fio --server=1.2.3.4`` |
| |
| Start a fio server, listening on IP 1.2.3.4 on the default port. |
| |
| 6) ``fio --server=sock:/tmp/fio.sock`` |
| |
| Start a fio server, listening on the local socket :file:`/tmp/fio.sock`. |
| |
| Once a server is running, a "client" can connect to the fio server with:: |
| |
| fio <local-args> --client=<server> <remote-args> <job file(s)> |
| |
| where `local-args` are arguments for the client where it is running, `server` |
| is the connect string, and `remote-args` and `job file(s)` are sent to the |
| server. The `server` string follows the same format as it does on the server |
| side, to allow IP/hostname/socket and port strings. |
| |
| Fio can connect to multiple servers this way:: |
| |
| fio --client=<server1> <job file(s)> --client=<server2> <job file(s)> |
| |
| If the job file is located on the fio server, then you can tell the server to |
| load a local file as well. This is done by using :option:`--remote-config` :: |
| |
| fio --client=server --remote-config /path/to/file.fio |
| |
| Then fio will open this local (to the server) job file instead of being passed |
| one from the client. |
| |
| If you have many servers (example: 100 VMs/containers), you can input a pathname |
| of a file containing host IPs/names as the parameter value for the |
| :option:`--client` option. For example, here is an example :file:`host.list` |
| file containing 2 hostnames:: |
| |
| host1.your.dns.domain |
| host2.your.dns.domain |
| |
| The fio command would then be:: |
| |
| fio --client=host.list <job file(s)> |
| |
| In this mode, you cannot input server-specific parameters or job files -- all |
| servers receive the same job file. |
| |
| In order to let ``fio --client`` runs use a shared filesystem from multiple |
| hosts, ``fio --client`` now prepends the IP address of the server to the |
| filename. For example, if fio is using the directory :file:`/mnt/nfs/fio` and is |
| writing filename :file:`fileio.tmp`, with a :option:`--client` `hostfile` |
| containing two hostnames ``h1`` and ``h2`` with IP addresses 192.168.10.120 and |
| 192.168.10.121, then fio will create two files:: |
| |
| /mnt/nfs/fio/192.168.10.120.fileio.tmp |
| /mnt/nfs/fio/192.168.10.121.fileio.tmp |
| |
| Terse output in client/server mode will differ slightly from what is produced |
| when fio is run in stand-alone mode. See the terse output section for details. |