linux-imx/Documentation/ABI/testing/procfs-smaps_rollup
Vincent Whitchurch 3093484301 mm/smaps: add Pss_Dirty
Pss is the sum of the sizes of clean and dirty private pages, and the
proportional sizes of clean and dirty shared pages:

 Private = Private_Dirty + Private_Clean
 Shared_Proportional = Shared_Dirty_Proportional + Shared_Clean_Proportional
 Pss = Private + Shared_Proportional

The Shared*Proportional fields are not present in smaps, so it is not
always possible to determine how much of the Pss is from dirty pages and
how much is from clean pages.  This information can be useful for
measuring memory usage for the purpose of optimisation, since clean pages
can usually be discarded by the kernel immediately while dirty pages
cannot.

The smaps routines in the kernel already have access to this data, so add
a Pss_Dirty to show it to userspace.  Pss_Clean is not added since it can
be calculated from Pss and Pss_Dirty.

Link: https://lkml.kernel.org/r/20220620081251.2928103-1-vincent.whitchurch@axis.com
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-07-03 18:08:49 -07:00

1.4 KiB

What: /proc/pid/smaps_rollup Date: August 2017 Contact: Daniel Colascione dancol@google.com Description: This file provides pre-summed memory information for a process. The format is almost identical to /proc/pid/smaps, except instead of an entry for each VMA in a process, smaps_rollup has a single entry (tagged "[rollup]") for which each field is the sum of the corresponding fields from all the maps in /proc/pid/smaps. Additionally, the fields Pss_Anon, Pss_File and Pss_Shmem are not present in /proc/pid/smaps. These fields represent the sum of the Pss field of each type (anon, file, shmem). For more details, see Documentation/filesystems/proc.rst and the procfs man page.

	Typical output looks like this::

		00100000-ff709000 ---p 00000000 00:00 0		 [rollup]
		Size:               1192 kB
		KernelPageSize:        4 kB
		MMUPageSize:           4 kB
		Rss:		     884 kB
		Pss:		     385 kB
		Pss_Dirty:	      68 kB
		Pss_Anon:	     301 kB
		Pss_File:	      80 kB
		Pss_Shmem:	       4 kB
		Shared_Clean:	     696 kB
		Shared_Dirty:	       0 kB
		Private_Clean:	     120 kB
		Private_Dirty:	      68 kB
		Referenced:	     884 kB
		Anonymous:	      68 kB
		LazyFree:	       0 kB
		AnonHugePages:	       0 kB
		ShmemPmdMapped:	       0 kB
		Shared_Hugetlb:	       0 kB
		Private_Hugetlb:       0 kB
		Swap:		       0 kB
		SwapPss:	       0 kB
		Locked:		     385 kB