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Report separate components (anon, file, and shmem) for PSS in smaps_rollup. This helps understand and tune the memory manager behavior in consumer devices, particularly mobile devices. Many of them (e.g. chromebooks and Android-based devices) use zram for anon memory, and perform disk reads for discarded file pages. The difference in latency is large (e.g. reading a single page from SSD is 30 times slower than decompressing a zram page on one popular device), thus it is useful to know how much of the PSS is anon vs. file. All the information is already present in /proc/pid/smaps, but much more expensive to obtain because of the large size of that procfs entry. This patch also removes a small code duplication in smaps_account, which would have gotten worse otherwise. Also updated Documentation/filesystems/proc.txt (the smaps section was a bit stale, and I added a smaps_rollup section) and Documentation/ABI/testing/procfs-smaps_rollup. [semenzato@chromium.org: v5] Link: http://lkml.kernel.org/r/20190626234333.44608-1-semenzato@chromium.org Link: http://lkml.kernel.org/r/20190626180429.174569-1-semenzato@chromium.org Signed-off-by: Luigi Semenzato <semenzato@chromium.org> Acked-by: Yu Zhao <yuzhao@chromium.org> Cc: Sonny Rao <sonnyrao@chromium.org> Cc: Yu Zhao <yuzhao@chromium.org> Cc: Brian Geffon <bgeffon@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
41 lines
1.3 KiB
Text
41 lines
1.3 KiB
Text
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.txt
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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_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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