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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>
43 lines
1.4 KiB
Plaintext
43 lines
1.4 KiB
Plaintext
What: /proc/pid/smaps_rollup
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Date: August 2017
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Contact: Daniel Colascione <dancol@google.com>
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Description:
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This file provides pre-summed memory information for a
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process. The format is almost identical to /proc/pid/smaps,
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except instead of an entry for each VMA in a process,
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smaps_rollup has a single entry (tagged "[rollup]")
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for which each field is the sum of the corresponding
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fields from all the maps in /proc/pid/smaps.
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Additionally, the fields Pss_Anon, Pss_File and Pss_Shmem
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are not present in /proc/pid/smaps. These fields represent
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the sum of the Pss field of each type (anon, file, shmem).
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For more details, see Documentation/filesystems/proc.rst
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and the procfs man page.
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Typical output looks like this::
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00100000-ff709000 ---p 00000000 00:00 0 [rollup]
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Size: 1192 kB
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KernelPageSize: 4 kB
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MMUPageSize: 4 kB
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Rss: 884 kB
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Pss: 385 kB
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Pss_Dirty: 68 kB
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Pss_Anon: 301 kB
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Pss_File: 80 kB
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Pss_Shmem: 4 kB
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Shared_Clean: 696 kB
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Shared_Dirty: 0 kB
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Private_Clean: 120 kB
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Private_Dirty: 68 kB
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Referenced: 884 kB
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Anonymous: 68 kB
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LazyFree: 0 kB
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AnonHugePages: 0 kB
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ShmemPmdMapped: 0 kB
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Shared_Hugetlb: 0 kB
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Private_Hugetlb: 0 kB
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Swap: 0 kB
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SwapPss: 0 kB
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Locked: 385 kB
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