Commit 0bc126d4 authored by Rodrigo Freire's avatar Rodrigo Freire Committed by Linus Torvalds

Documentation/filesystems: describe the shared memory usage/accounting

The Shared Memory accounting support is present in Kernel since commit
4b02108a ("mm: oom analysis: add shmem vmstat") and in userland
free(1) since 2014.  This patch updates the Documentation to reflect
this change.
Signed-off-by: default avatarRodrigo Freire <rfreire@redhat.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6f754ba4
...@@ -855,6 +855,7 @@ Dirty: 968 kB ...@@ -855,6 +855,7 @@ Dirty: 968 kB
Writeback: 0 kB Writeback: 0 kB
AnonPages: 861800 kB AnonPages: 861800 kB
Mapped: 280372 kB Mapped: 280372 kB
Shmem: 644 kB
Slab: 284364 kB Slab: 284364 kB
SReclaimable: 159856 kB SReclaimable: 159856 kB
SUnreclaim: 124508 kB SUnreclaim: 124508 kB
...@@ -911,6 +912,7 @@ MemAvailable: An estimate of how much memory is available for starting new ...@@ -911,6 +912,7 @@ MemAvailable: An estimate of how much memory is available for starting new
AnonPages: Non-file backed pages mapped into userspace page tables AnonPages: Non-file backed pages mapped into userspace page tables
AnonHugePages: Non-file backed huge pages mapped into userspace page tables AnonHugePages: Non-file backed huge pages mapped into userspace page tables
Mapped: files which have been mmaped, such as libraries Mapped: files which have been mmaped, such as libraries
Shmem: Total memory used by shared memory (shmem) and tmpfs
Slab: in-kernel data structures cache Slab: in-kernel data structures cache
SReclaimable: Part of Slab, that might be reclaimed, such as caches SReclaimable: Part of Slab, that might be reclaimed, such as caches
SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure SUnreclaim: Part of Slab, that cannot be reclaimed on memory pressure
......
...@@ -17,10 +17,10 @@ RAM, where you have to create an ordinary filesystem on top. Ramdisks ...@@ -17,10 +17,10 @@ RAM, where you have to create an ordinary filesystem on top. Ramdisks
cannot swap and you do not have the possibility to resize them. cannot swap and you do not have the possibility to resize them.
Since tmpfs lives completely in the page cache and on swap, all tmpfs Since tmpfs lives completely in the page cache and on swap, all tmpfs
pages currently in memory will show up as cached. It will not show up pages will be shown as "Shmem" in /proc/meminfo and "Shared" in
as shared or something like that. Further on you can check the actual free(1). Notice that these counters also include shared memory
RAM+swap use of a tmpfs instance with df(1) and du(1). (shmem, see ipcs(1)). The most reliable way to get the count is
using df(1) and du(1).
tmpfs has the following uses: tmpfs has the following uses:
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment