vmscan: stop kswapd waiting on congestion when the min watermark is not being met
authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Tue, 15 Dec 2009 01:58:55 +0000 (17:58 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 15 Dec 2009 16:53:16 +0000 (08:53 -0800)
commitbb3ab596832b920c703d1aea1ce76d69c0f71fb7
tree048162bf5081e7bd9802eba012e8b680a4444da8
parentf50de2d3811081957156b5d736778799379c29de
vmscan: stop kswapd waiting on congestion when the min watermark is not being met

If reclaim fails to make sufficient progress, the priority is raised.
Once the priority is higher, kswapd starts waiting on congestion.
However, if the zone is below the min watermark then kswapd needs to
continue working without delay as there is a danger of an increased rate
of GFP_ATOMIC allocation failure.

This patch changes the conditions under which kswapd waits on congestion
by only going to sleep if the min watermarks are being met.

[mel@csn.ul.ie: add stats to track how relevant the logic is]
[mel@csn.ul.ie: make kswapd only check its own zones and rename the relevant counters]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/vmstat.h
mm/vmscan.c
mm/vmstat.c