maps4: add proportional set size accounting in smaps
The "proportional set size" (PSS) of a process is the count of pages it has
in memory, where each page is divided by the number of processes sharing
it. So if a process has 1000 pages all to itself, and 1000 shared with one
other process, its PSS will be 1500.
- lwn.net: "ELC: How much memory are applications really using?"
The PSS proposed by Matt Mackall is a very nice metic for measuring an
process's memory footprint. So collect and export it via
/proc/<pid>/smaps.
Matt Mackall's pagemap/kpagemap and John Berthels's exmap can also do the
job. They are comprehensive tools. But for PSS, let's do it in the simple
way.
Cc: John Berthels <[email protected]>
Cc: Bernardo Innocenti <[email protected]>
Cc: Padraig Brady <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Balbir Singh <[email protected]>
Signed-off-by: Matt Mackall <[email protected]>
Signed-off-by: Fengguang Wu <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Dave Hansen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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