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authorJerome Marchand2016-01-14 15:19:29 -0800
committerLinus Torvalds2016-01-14 16:00:49 -0800
commit8cee852ec53fb530f10ccabf1596734209ae336b (patch)
tree735d2730dcadecacf1aa6990d0589c14deb62b7e /Documentation
parenteca56ff906bdd0239485e8b47154a6e73dd9a2f3 (diff)
mm, procfs: breakdown RSS for anon, shmem and file in /proc/pid/status
There are several shortcomings with the accounting of shared memory (SysV shm, shared anonymous mapping, mapping of a tmpfs file). The values in /proc/<pid>/status and <...>/statm don't allow to distinguish between shmem memory and a shared mapping to a regular file, even though theirs implication on memory usage are quite different: during reclaim, file mapping can be dropped or written back on disk, while shmem needs a place in swap. Also, to distinguish the memory occupied by anonymous and file mappings, one has to read the /proc/pid/statm file, which has a field for the file mappings (again, including shmem) and total memory occupied by these mappings (i.e. equivalent to VmRSS in the <...>/status file. Getting the value for anonymous mappings only is thus not exactly user-friendly (the statm file is intended to be rather efficiently machine-readable). To address both of these shortcomings, this patch adds a breakdown of VmRSS in /proc/<pid>/status via new fields RssAnon, RssFile and RssShmem, making use of the previous preparatory patch. These fields tell the user the memory occupied by private anonymous pages, mapped regular files and shmem, respectively. Other existing fields in /status and /statm files are left without change. The /statm file can be extended in the future, if there's a need for that. Example (part of) /proc/pid/status output including the new Rss* fields: VmPeak: 2001008 kB VmSize: 2001004 kB VmLck: 0 kB VmPin: 0 kB VmHWM: 5108 kB VmRSS: 5108 kB RssAnon: 92 kB RssFile: 1324 kB RssShmem: 3692 kB VmData: 192 kB VmStk: 136 kB VmExe: 4 kB VmLib: 1784 kB VmPTE: 3928 kB VmPMD: 20 kB VmSwap: 0 kB HugetlbPages: 0 kB [vbabka@suse.cz: forward-porting, tweak changelog] Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/filesystems/proc.txt13
1 files changed, 11 insertions, 2 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index fdeb5b33349f..ffcd49589ab5 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -169,6 +169,9 @@ read the file /proc/PID/status:
VmLck: 0 kB
VmHWM: 476 kB
VmRSS: 476 kB
+ RssAnon: 352 kB
+ RssFile: 120 kB
+ RssShmem: 4 kB
VmData: 156 kB
VmStk: 88 kB
VmExe: 68 kB
@@ -231,7 +234,12 @@ Table 1-2: Contents of the status files (as of 4.1)
VmSize total program size
VmLck locked memory size
VmHWM peak resident set size ("high water mark")
- VmRSS size of memory portions
+ VmRSS size of memory portions. It contains the three
+ following parts (VmRSS = RssAnon + RssFile + RssShmem)
+ RssAnon size of resident anonymous memory
+ RssFile size of resident file mappings
+ RssShmem size of resident shmem memory (includes SysV shm,
+ mapping of tmpfs and shared anonymous mappings)
VmData size of data, stack, and text segments
VmStk size of data, stack, and text segments
VmExe size of text segment
@@ -266,7 +274,8 @@ Table 1-3: Contents of the statm files (as of 2.6.8-rc3)
Field Content
size total program size (pages) (same as VmSize in status)
resident size of memory portions (pages) (same as VmRSS in status)
- shared number of pages that are shared (i.e. backed by a file)
+ shared number of pages that are shared (i.e. backed by a file, same
+ as RssFile+RssShmem in status)
trs number of pages that are 'code' (not including libs; broken,
includes data segment)
lrs number of pages of library (always 0 on 2.6)