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| .TH AIO_INIT 3 2020-08-13 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| aio_init \- asynchronous I/O initialization |
| .SH SYNOPSIS |
| .nf |
| .BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */" |
| .B "#include <aio.h>" |
| .PP |
| .BI "void aio_init(const struct aioinit *" init ); |
| .fi |
| .PP |
| Link with \fI\-lrt\fP. |
| .SH DESCRIPTION |
| The GNU-specific |
| .BR aio_init () |
| function allows the caller to provide tuning hints to the |
| glibc POSIX AIO implementation. |
| Use of this function is optional, but to be effective, |
| it must be called before employing any other functions in the POSIX AIO API. |
| .PP |
| The tuning information is provided in the buffer pointed to by the argument |
| .IR init . |
| This buffer is a structure of the following form: |
| .PP |
| .in +4n |
| .EX |
| struct aioinit { |
| int aio_threads; /* Maximum number of threads */ |
| int aio_num; /* Number of expected simultaneous |
| requests */ |
| int aio_locks; /* Not used */ |
| int aio_usedba; /* Not used */ |
| int aio_debug; /* Not used */ |
| int aio_numusers; /* Not used */ |
| int aio_idle_time; /* Number of seconds before idle thread |
| terminates (since glibc 2.2) */ |
| int aio_reserved; |
| }; |
| .EE |
| .in |
| .PP |
| The following fields are used in the |
| .I aioinit |
| structure: |
| .TP |
| .I aio_threads |
| This field specifies the maximum number of worker threads that |
| may be used by the implementation. |
| If the number of outstanding I/O operations exceeds this limit, |
| then excess operations will be queued until a worker thread becomes free. |
| If this field is specified with a value less than 1, the value 1 is used. |
| The default value is 20. |
| .TP |
| .I aio_num |
| This field should specify the maximum number of simultaneous I/O requests |
| that the caller expects to enqueue. |
| If a value less than 32 is specified for this field, |
| it is rounded up to 32. |
| .\" FIXME . But, if aio_num > 32, the behavior looks strange. See |
| .\" http://sourceware.org/bugzilla/show_bug.cgi?id=12083 |
| The default value is 64. |
| .TP |
| .I aio_idle_time |
| This field specifies the amount of time in seconds that a |
| worker thread should wait for further requests before terminating, |
| after having completed a previous request. |
| The default value is 1. |
| .SH VERSIONS |
| The |
| .BR aio_init () |
| function is available since glibc 2.1. |
| .SH CONFORMING TO |
| This function is a GNU extension. |
| .SH SEE ALSO |
| .BR aio (7) |