mm: smaps: split PSS into components

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.

[[email protected]: v5]
  Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Luigi Semenzato <[email protected]>
Acked-by: Yu Zhao <[email protected]>
Cc: Sonny Rao <[email protected]>
Cc: Yu Zhao <[email protected]>
Cc: Brian Geffon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions