| From: Johannes Weiner <hannes@cmpxchg.org> |
| Subject: Documentation: filesystems: proc: update meminfo section |
| |
| Patch series "zswap: accounting & cgroup control", v2. |
| |
| Zswap can consume nearly a quarter of RAM in the default configuration, |
| yet it's neither listed in /proc/meminfo, nor is it accounted and |
| manageable on a per-cgroup basis. |
| |
| This makes reasoning about the memory situation on a host in general |
| rather difficult. On shared/cgrouped hosts, the consequences are worse. |
| First, workloads can escape memory containment and cause resource priority |
| inversions: a lo-pri group can fill the global zswap pool and force a |
| hi-pri group out to disk. Second, not all workloads benefit from zswap |
| equally. Some even suffer when memory contents compress poorly, and are |
| better off going to disk swap directly. On a host with mixed workloads, |
| it's currently not possible to enable zswap for one workload but not for |
| the other. |
| |
| This series implements the missing global accounting as well as cgroup |
| tracking & control for zswap backing memory: |
| |
| - Patch 1 refreshes the very out-of-date meminfo documentation in |
| Documentation/filesystems/proc.rst. |
| |
| - Patches 2-4 clean up related and adjacent options in Kconfig. Not |
| actual dependencies, just things I noticed during development. |
| |
| - Patch 5 adds meminfo and vmstat coverage for zswap consumption and |
| activity. |
| |
| - Patch 6 implements per-cgroup tracking & control of zswap memory. |
| |
| |
| This patch (of 6): |
| |
| Add new entries. Minor corrections and cleanups. |
| |
| [hannes@cmpxchg.org: fix htmldocs warnings] |
| Link: https://lkml.kernel.org/r/Ynve8dg4zJyhH2gW@cmpxchg.org |
| [hannes@cmpxchg.org: change `Unevictable' wording, per David] |
| Link: https://lkml.kernel.org/r/YnwFraZlVWQoCjz3@cmpxchg.org |
| Link: https://lkml.kernel.org/r/20220510152847.230957-1-hannes@cmpxchg.org |
| Link: https://lkml.kernel.org/r/20220510152847.230957-2-hannes@cmpxchg.org |
| Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> |
| Acked-by: David Hildenbrand <david@redhat.com> |
| Cc: Dan Streetman <ddstreet@ieee.org> |
| Cc: Michal Hocko <mhocko@suse.com> |
| Cc: Minchan Kim <minchan@kernel.org> |
| Cc: Roman Gushchin <guro@fb.com> |
| Cc: Seth Jennings <sjenning@redhat.com> |
| Cc: Shakeel Butt <shakeelb@google.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| --- |
| |
| Documentation/filesystems/proc.rst | 148 ++++++++++++++++----------- |
| 1 file changed, 92 insertions(+), 56 deletions(-) |
| |
| --- a/Documentation/filesystems/proc.rst~documentation-filesystems-proc-update-meminfo-section |
| +++ a/Documentation/filesystems/proc.rst |
| @@ -942,56 +942,71 @@ can be substantial. In many cases there |
| additional memory using subsystem specific interfaces, for instance |
| /proc/net/sockstat for TCP memory allocations. |
| |
| -The following is from a 16GB PIII, which has highmem enabled. |
| -You may not have all of these fields. |
| +Example output. You may not have all of these fields. |
| |
| :: |
| |
| > cat /proc/meminfo |
| |
| - MemTotal: 16344972 kB |
| - MemFree: 13634064 kB |
| - MemAvailable: 14836172 kB |
| - Buffers: 3656 kB |
| - Cached: 1195708 kB |
| - SwapCached: 0 kB |
| - Active: 891636 kB |
| - Inactive: 1077224 kB |
| - HighTotal: 15597528 kB |
| - HighFree: 13629632 kB |
| - LowTotal: 747444 kB |
| - LowFree: 4432 kB |
| - SwapTotal: 0 kB |
| - SwapFree: 0 kB |
| - Dirty: 968 kB |
| - Writeback: 0 kB |
| - AnonPages: 861800 kB |
| - Mapped: 280372 kB |
| - Shmem: 644 kB |
| - KReclaimable: 168048 kB |
| - Slab: 284364 kB |
| - SReclaimable: 159856 kB |
| - SUnreclaim: 124508 kB |
| - PageTables: 24448 kB |
| - NFS_Unstable: 0 kB |
| - Bounce: 0 kB |
| - WritebackTmp: 0 kB |
| - CommitLimit: 7669796 kB |
| - Committed_AS: 100056 kB |
| - VmallocTotal: 112216 kB |
| - VmallocUsed: 428 kB |
| - VmallocChunk: 111088 kB |
| - Percpu: 62080 kB |
| - HardwareCorrupted: 0 kB |
| - AnonHugePages: 49152 kB |
| - ShmemHugePages: 0 kB |
| - ShmemPmdMapped: 0 kB |
| + MemTotal: 32858820 kB |
| + MemFree: 21001236 kB |
| + MemAvailable: 27214312 kB |
| + Buffers: 581092 kB |
| + Cached: 5587612 kB |
| + SwapCached: 0 kB |
| + Active: 3237152 kB |
| + Inactive: 7586256 kB |
| + Active(anon): 94064 kB |
| + Inactive(anon): 4570616 kB |
| + Active(file): 3143088 kB |
| + Inactive(file): 3015640 kB |
| + Unevictable: 0 kB |
| + Mlocked: 0 kB |
| + SwapTotal: 0 kB |
| + SwapFree: 0 kB |
| + Dirty: 12 kB |
| + Writeback: 0 kB |
| + AnonPages: 4654780 kB |
| + Mapped: 266244 kB |
| + Shmem: 9976 kB |
| + KReclaimable: 517708 kB |
| + Slab: 660044 kB |
| + SReclaimable: 517708 kB |
| + SUnreclaim: 142336 kB |
| + KernelStack: 11168 kB |
| + PageTables: 20540 kB |
| + NFS_Unstable: 0 kB |
| + Bounce: 0 kB |
| + WritebackTmp: 0 kB |
| + CommitLimit: 16429408 kB |
| + Committed_AS: 7715148 kB |
| + VmallocTotal: 34359738367 kB |
| + VmallocUsed: 40444 kB |
| + VmallocChunk: 0 kB |
| + Percpu: 29312 kB |
| + HardwareCorrupted: 0 kB |
| + AnonHugePages: 4149248 kB |
| + ShmemHugePages: 0 kB |
| + ShmemPmdMapped: 0 kB |
| + FileHugePages: 0 kB |
| + FilePmdMapped: 0 kB |
| + CmaTotal: 0 kB |
| + CmaFree: 0 kB |
| + HugePages_Total: 0 |
| + HugePages_Free: 0 |
| + HugePages_Rsvd: 0 |
| + HugePages_Surp: 0 |
| + Hugepagesize: 2048 kB |
| + Hugetlb: 0 kB |
| + DirectMap4k: 401152 kB |
| + DirectMap2M: 10008576 kB |
| + DirectMap1G: 24117248 kB |
| |
| MemTotal |
| Total usable RAM (i.e. physical RAM minus a few reserved |
| bits and the kernel binary code) |
| MemFree |
| - The sum of LowFree+HighFree |
| + Total free RAM. On highmem systems, the sum of LowFree+HighFree |
| MemAvailable |
| An estimate of how much memory is available for starting new |
| applications, without swapping. Calculated from MemFree, |
| @@ -1005,8 +1020,9 @@ Buffers |
| Relatively temporary storage for raw disk blocks |
| shouldn't get tremendously large (20MB or so) |
| Cached |
| - in-memory cache for files read from the disk (the |
| - pagecache). Doesn't include SwapCached |
| + In-memory cache for files read from the disk (the |
| + pagecache) as well as tmpfs & shmem. |
| + Doesn't include SwapCached. |
| SwapCached |
| Memory that once was swapped out, is swapped back in but |
| still also is in the swapfile (if memory is needed it |
| @@ -1018,6 +1034,11 @@ Active |
| Inactive |
| Memory which has been less recently used. It is more |
| eligible to be reclaimed for other purposes |
| +Unevictable |
| + Memory allocated for userspace which cannot be reclaimed, such |
| + as mlocked pages, ramfs backing pages, secret memfd pages etc. |
| +Mlocked |
| + Memory locked with mlock(). |
| HighTotal, HighFree |
| Highmem is all memory above ~860MB of physical memory. |
| Highmem areas are for use by userspace programs, or |
| @@ -1040,20 +1061,10 @@ Writeback |
| Memory which is actively being written back to the disk |
| AnonPages |
| Non-file backed pages mapped into userspace page tables |
| -HardwareCorrupted |
| - The amount of RAM/memory in KB, the kernel identifies as |
| - corrupted. |
| -AnonHugePages |
| - Non-file backed huge pages mapped into userspace page tables |
| Mapped |
| files which have been mmaped, such as libraries |
| Shmem |
| Total memory used by shared memory (shmem) and tmpfs |
| -ShmemHugePages |
| - Memory used by shared memory (shmem) and tmpfs allocated |
| - with huge pages |
| -ShmemPmdMapped |
| - Shared memory mapped into userspace with huge pages |
| KReclaimable |
| Kernel allocations that the kernel will attempt to reclaim |
| under memory pressure. Includes SReclaimable (below), and other |
| @@ -1064,9 +1075,10 @@ SReclaimable |
| Part of Slab, that might be reclaimed, such as caches |
| SUnreclaim |
| Part of Slab, that cannot be reclaimed on memory pressure |
| +KernelStack |
| + Memory consumed by the kernel stacks of all tasks |
| PageTables |
| - amount of memory dedicated to the lowest level of page |
| - tables. |
| + Memory consumed by userspace page tables |
| NFS_Unstable |
| Always zero. Previous counted pages which had been written to |
| the server, but has not been committed to stable storage. |
| @@ -1098,7 +1110,7 @@ Committed_AS |
| has been allocated by processes, even if it has not been |
| "used" by them as of yet. A process which malloc()'s 1G |
| of memory, but only touches 300M of it will show up as |
| - using 1G. This 1G is memory which has been "committed" to |
| + using 1G. This 1G is memory which has been "committed" to |
| by the VM and can be used at any time by the allocating |
| application. With strict overcommit enabled on the system |
| (mode 2 in 'vm.overcommit_memory'), allocations which would |
| @@ -1107,7 +1119,7 @@ Committed_AS |
| not fail due to lack of memory once that memory has been |
| successfully allocated. |
| VmallocTotal |
| - total size of vmalloc memory area |
| + total size of vmalloc virtual address space |
| VmallocUsed |
| amount of vmalloc area which is used |
| VmallocChunk |
| @@ -1115,6 +1127,30 @@ VmallocChunk |
| Percpu |
| Memory allocated to the percpu allocator used to back percpu |
| allocations. This stat excludes the cost of metadata. |
| +HardwareCorrupted |
| + The amount of RAM/memory in KB, the kernel identifies as |
| + corrupted. |
| +AnonHugePages |
| + Non-file backed huge pages mapped into userspace page tables |
| +ShmemHugePages |
| + Memory used by shared memory (shmem) and tmpfs allocated |
| + with huge pages |
| +ShmemPmdMapped |
| + Shared memory mapped into userspace with huge pages |
| +FileHugePages |
| + Memory used for filesystem data (page cache) allocated |
| + with huge pages |
| +FilePmdMapped |
| + Page cache mapped into userspace with huge pages |
| +CmaTotal |
| + Memory reserved for the Contiguous Memory Allocator (CMA) |
| +CmaFree |
| + Free remaining memory in the CMA reserves |
| +HugePages_Total, HugePages_Free, HugePages_Rsvd, HugePages_Surp, Hugepagesize, Hugetlb |
| + See Documentation/admin-guide/mm/hugetlbpage.rst. |
| +DirectMap4k, DirectMap2M, DirectMap1G |
| + Breakdown of page table sizes used in the kernel's |
| + identity mapping of RAM |
| |
| vmallocinfo |
| ~~~~~~~~~~~ |
| _ |
