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[PACTH v3 0/3] Implement /proc/<pid>/totmaps

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  [PACTH v3 0/3] Implement /proc/<pid>/totmaps robert.foss@collabora.com - 2016-08-16 19:40 +0200
    [PACTH v3 3/3] Documentation/filesystems: Added /proc/PID/totmaps documentation robert.foss@collabora.com - 2016-08-16 19:40 +0200
      Re: [PACTH v3 3/3] Documentation/filesystems: Added  /proc/PID/totmaps documentation Jann Horn <jann@thejh.net> - 2016-08-16 20:10 +0200
        Re: [PACTH v3 3/3] Documentation/filesystems: Added /proc/PID/totmaps  documentation Robert Foss <robert.foss@collabora.com> - 2016-08-16 20:30 +0200

#1463966 — [PACTH v3 0/3] Implement /proc/<pid>/totmaps

From: Robert Foss <robert.foss@collabora.com>

This series provides the /proc/PID/totmaps feature, which 
summarizes the information provided by /proc/PID/smaps for
improved performance and usability reasons.

A use case is to speed up monitoring of memory consumption in 
environments where RSS isn't precise.

For example Chrome tends to many processes which have hundreds of VMAs
with a substantial amount of shared memory, and the error of using
RSS rather than PSS tends to be very large when looking at overall
memory consumption.  PSS isn't kept as a single number that's exported
like RSS, so to calculate PSS means having to parse a very large smaps
file.

This process is slow and has to be repeated for many processes, and we
found that the just act of doing the parsing was taking up a
significant amount of CPU time, so this patch is an attempt to make
that process cheaper.

/proc/PID/totmaps provides roughly a 2x speedup compared to parsing
/proc/PID/smaps with awk.

$ /usr/bin/time -v -p zsh -c "(repeat 25 {cat /proc/5025/totmaps})"
[...]
        Command being timed: "zsh -c (repeat 25 {cat /proc/5025/totmaps})"
        User time (seconds): 0.00
        System time (seconds): 0.40
        Percent of CPU this job got: 90%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.45


$ /usr/bin/time -v -p zsh -c "repeat 25 { awk '/^Rss/{rss+=\$2} /^Pss/{pss+=\$2} END {printf \"rss:%d pss:%d\n\", rss, pss}\' /proc/5025/smaps}"
[...]
        Command being timed: "zsh -c repeat 25 { awk '/^Rss/{rss+=$2}
/^Pss/{pss+=$2} END {printf "rss:%d pss:%d\n", rss, pss}\' /proc/5025/smaps }"
        User time (seconds): 0.37
        System time (seconds): 0.45
        Percent of CPU this job got: 92%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.89

Robert Foss (3):
  mm, proc: Implement /proc/<pid>/totmaps
  Documentation/filesystems: Fixed typo
  Documentation/filesystems: Added /proc/PID/totmaps documentation

 Documentation/filesystems/proc.txt |  23 ++++++-
 fs/proc/base.c                     |   1 +
 fs/proc/internal.h                 |   2 +
 fs/proc/task_mmu.c                 | 129 +++++++++++++++++++++++++++++++++++++
 4 files changed, 154 insertions(+), 1 deletion(-)

-- 
2.7.4

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#1463967 — [PACTH v3 3/3] Documentation/filesystems: Added /proc/PID/totmaps documentation

From: Robert Foss <robert.foss@collabora.com>

Added documentation covering /proc/PID/totmaps.

Signed-off-by: Robert Foss <robert.foss@collabora.com>
---
 Documentation/filesystems/proc.txt | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 7d001be..c06ff33 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -11,6 +11,7 @@ Version 1.3                                              Kernel version 2.2.12
 					      Kernel version 2.4.0-test11-pre4
 ------------------------------------------------------------------------------
 fixes/update part 1.1  Stefani Seibold <stefani@seibold.net>       June 9 2009
+add totmaps            Robert Foss <robert.foss@collabora.com>  August 12 2016
 
 Table of Contents
 -----------------
@@ -147,6 +148,8 @@ Table 1-1: Process specific entries in /proc
  stack		Report full stack trace, enable via CONFIG_STACKTRACE
  smaps		an extension based on maps, showing the memory consumption of
 		each mapping and flags associated with it
+ totmaps        an extenssion based on maps, showing the total memory
+                consumption of all mappings
  numa_maps	an extension based on maps, showing the memory locality and
 		binding policy as well as mem usage (in pages) of each mapping.
 ..............................................................................
@@ -512,6 +515,24 @@ be vanished or the reverse -- new added.
 This file is only present if the CONFIG_MMU kernel configuration option is
 enabled.
 
+The /proc/PID/totmaps is an extension based on maps, showing the memory
+consumption totals for all of the process's mappings. It lists the sums of the
+same statistics as /proc/PID/smaps.
+
+The process' mappings will be summarized as a series of lines like the
+following:
+
+Rss:                4256 kB
+Pss:                1170 kB
+Shared_Clean:       2720 kB
+Shared_Dirty:       1136 kB
+Private_Clean:         0 kB
+Private_Dirty:       400 kB
+Referenced:         4256 kB
+Anonymous:          1536 kB
+AnonHugePages:         0 kB
+Swap:                  0 kB
+
 The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG
 bits on both physical and virtual pages associated with a process, and the
 soft-dirty bit on pte (see Documentation/vm/soft-dirty.txt for details).
-- 
2.7.4

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#1463982 — Re: [PACTH v3 3/3] Documentation/filesystems: Added /proc/PID/totmaps documentation

[Multipart message — attachments visible in raw view] — view raw

On Tue, Aug 16, 2016 at 01:34:16PM -0400, robert.foss@collabora.com wrote:
> + totmaps        an extenssion based on maps, showing the total memory
> +                consumption of all mappings

nit: s/extenssion/extension/

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#1464003 — Re: [PACTH v3 3/3] Documentation/filesystems: Added /proc/PID/totmaps documentation

On 2016-08-16 02:01 PM, Jann Horn wrote:
> nit: s/extenssion/extension/

Thanks :)

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