linux/fs/proc
David Rientjes b813e931b4 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 <hugh@veritas.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: David Rientjes <rientjes@google.com>
[akpm@linux-foundation.org: build fixes]
[mpm@selenic.com: rename for_each_pmd]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07 12:12:52 -07:00
..
array.c [PATCH] tty: update the tty layer to work with struct pid 2007-02-12 09:48:32 -08:00
base.c smaps: add clear_refs file to clear reference 2007-05-07 12:12:52 -07:00
generic.c [PATCH] sysctl: reimplement the sysctl proc support 2007-02-14 08:10:00 -08:00
inode-alloc.txt Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
inode.c [PATCH] sysctl: reimplement the sysctl proc support 2007-02-14 08:10:00 -08:00
internal.h [PATCH] proc: fix linkage with CONFIG_SYSCTL=y, CONFIG_PROC_SYSCTL=n 2007-04-02 10:06:08 -07:00
kcore.c [PATCH] elf: fix kcore note size calculation 2006-12-07 08:39:38 -08:00
kmsg.c [PATCH] Make most file operations structs in fs/ const 2006-03-28 09:16:06 -08:00
Makefile [PATCH] Fix kernel build with EMBEDDED & PROC_FS & !PROC_SYSCTL 2007-03-27 09:05:16 -07:00
mmu.c [PATCH] fix impossible VmallocChunk 2005-05-17 07:59:10 -07:00
nommu.c [PATCH] mark struct file_operations const 6 2007-02-12 09:48:45 -08:00
proc_devtree.c [POWERPC] Make struct property's value a void * 2007-04-13 03:55:18 +10:00
proc_misc.c mm/slab.c: proper prototypes 2007-05-07 12:12:52 -07:00
proc_sysctl.c [PATCH] sysctl: hide the sysctl proc inodes from selinux 2007-02-14 08:10:00 -08:00
proc_tty.c [PATCH] mark struct file_operations const 6 2007-02-12 09:48:45 -08:00
root.c [PATCH] proc: fix linkage with CONFIG_SYSCTL=y, CONFIG_PROC_SYSCTL=n 2007-04-02 10:06:08 -07:00
task_mmu.c smaps: add clear_refs file to clear reference 2007-05-07 12:12:52 -07:00
task_nommu.c [PATCH] mark struct file_operations const 6 2007-02-12 09:48:45 -08:00
vmcore.c [PATCH] i386: Allow i386 crash kernels to handle x86_64 dumps 2007-05-02 19:27:09 +02:00