]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
mm, compaction: skip rechecks when lock was already held
authorVlastimil Babka <vbabka@suse.cz>
Thu, 9 Oct 2014 22:27:18 +0000 (15:27 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 10 Oct 2014 02:25:54 +0000 (22:25 -0400)
commit69b7189f12e0064237630e8c6bb64cad710bb268
tree5d486d214c347cba828477f8597db05617515c12
parent8b44d2791f912566a7ef58c71a7f9cbd16c3eeae
mm, compaction: skip rechecks when lock was already held

Compaction scanners try to lock zone locks as late as possible by checking
many page or pageblock properties opportunistically without lock and
skipping them if not unsuitable.  For pages that pass the initial checks,
some properties have to be checked again safely under lock.  However, if
the lock was already held from a previous iteration in the initial checks,
the rechecks are unnecessary.

This patch therefore skips the rechecks when the lock was already held.
This is now possible to do, since we don't (potentially) drop and
reacquire the lock between the initial checks and the safe rechecks
anymore.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/compaction.c