From b813e931b4c8235bb42e301096ea97dbdee3e8fe Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Sun, 6 May 2007 14:49:24 -0700 Subject: smaps: add clear_refs file to clear reference Adds /proc/pid/clear_refs. When any non-zero number is written to this file, pte_mkold() and ClearPageReferenced() is called for each pte and its corresponding page, respectively, in that task's VMAs. This file is only writable by the user who owns the task. It is now possible to measure _approximately_ how much memory a task is using by clearing the reference bits with echo 1 > /proc/pid/clear_refs and checking the reference count for each VMA from the /proc/pid/smaps output at a measured time interval. For example, to observe the approximate change in memory footprint for a task, write a script that clears the references (echo 1 > /proc/pid/clear_refs), sleeps, and then greps for Pgs_Referenced and extracts the size in kB. Add the sizes for each VMA together for the total referenced footprint. Moments later, repeat the process and observe the difference. For example, using an efficient Mozilla: accumulated time referenced memory ---------------- ----------------- 0 s 408 kB 1 s 408 kB 2 s 556 kB 3 s 1028 kB 4 s 872 kB 5 s 1956 kB 6 s 416 kB 7 s 1560 kB 8 s 2336 kB 9 s 1044 kB 10 s 416 kB This is a valuable tool to get an approximate measurement of the memory footprint for a task. Cc: Hugh Dickins Cc: Paul Mundt Cc: Christoph Lameter Signed-off-by: David Rientjes [akpm@linux-foundation.org: build fixes] [mpm@selenic.com: rename for_each_pmd] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/filesystems/proc.txt | 31 ++++++++++++++++--------------- 1 file changed, 16 insertions(+), 15 deletions(-) (limited to 'Documentation') diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 7aaf09b86a55..3f4b226572e7 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -122,21 +122,22 @@ subdirectory has the entries listed in Table 1-1. Table 1-1: Process specific entries in /proc .............................................................................. - File Content - cmdline Command line arguments - cpu Current and last cpu in which it was executed (2.4)(smp) - cwd Link to the current working directory - environ Values of environment variables - exe Link to the executable of this process - fd Directory, which contains all file descriptors - maps Memory maps to executables and library files (2.4) - mem Memory held by this process - root Link to the root directory of this process - stat Process status - statm Process memory status information - status Process status in human readable form - wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan - smaps Extension based on maps, presenting the rss size for each mapped file + File Content + clear_refs Clears page referenced bits shown in smaps output + cmdline Command line arguments + cpu Current and last cpu in which it was executed (2.4)(smp) + cwd Link to the current working directory + environ Values of environment variables + exe Link to the executable of this process + fd Directory, which contains all file descriptors + maps Memory maps to executables and library files (2.4) + mem Memory held by this process + root Link to the root directory of this process + stat Process status + statm Process memory status information + status Process status in human readable form + wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan + smaps Extension based on maps, the rss size for each mapped file .............................................................................. For example, to get the status information of a process, all you have to do is -- cgit v1.2.3