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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 16 Aug 2016 13:34:13 -0400
From:	robert.foss@...labora.com
To:	corbet@....net, akpm@...ux-foundation.org, vbabka@...e.cz,
	mhocko@...e.com, koct9i@...il.com, hughd@...gle.com,
	robert.foss@...labora.com, n-horiguchi@...jp.nec.com,
	john.stultz@...aro.org, minchan@...nel.org,
	ross.zwisler@...ux.intel.com, jmarchan@...hat.com,
	hannes@...xchg.org, mingo@...nel.org, keescook@...omium.org,
	viro@...iv.linux.org.uk, gorcunov@...nvz.org,
	sonnyrao@...omium.org, plaguedbypenguins@...il.com,
	eric.engestrom@...tec.com, rientjes@...gle.com, jdanis@...gle.com,
	calvinowens@...com, adobriyan@...il.com, jann@...jh.net,
	kirill.shutemov@...ux.intel.com, ldufour@...ux.vnet.ibm.com,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	Ben Zhang <benzh@...omium.org>,
	Bryan Freed <bfreed@...omium.org>,
	Filipe Brandenburger <filbranden@...omium.org>,
	Mateusz Guzik <mguzik@...hat.com>,
	Michal Hocko <mhocko@...nel.org>, linux-api@...r.kernel.org
Subject: [PACTH v3 0/3] Implement /proc/<pid>/totmaps

From: Robert Foss <robert.foss@...labora.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