vmscan: implement swap token priority aging
commitd7911ef30cb7bec52234c2b7a5c275ac8f07905a
authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Wed, 15 Jun 2011 22:08:15 +0000 (15 15:08 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 16 Jun 2011 03:03:59 +0000 (15 20:03 -0700)
treec3d9dc8ffc5d9478da434faecc27759ee34edf83
parent83cd81a34357a632509f7491eec81e62e71d65f7
vmscan: implement swap token priority aging

While testing for memcg aware swap token, I observed a swap token was
often grabbed an intermittent running process (eg init, auditd) and they
never release a token.

Why?

Some processes (eg init, auditd, audispd) wake up when a process exiting.
And swap token can be get first page-in process when a process exiting
makes no swap token owner.  Thus such above intermittent running process
often get a token.

And currently, swap token priority is only decreased at page fault path.
Then, if the process sleep immediately after to grab swap token, the swap
token priority never be decreased.  That's obviously undesirable.

This patch implement very poor (and lightweight) priority aging.  It only
be affect to the above corner case and doesn't change swap tendency
workload performance (eg multi process qsbench load)

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/trace/events/vmscan.h
mm/thrash.c