Messages in this thread | | | Date | Thu, 13 Dec 2012 11:12:54 +0000 | From | Mel Gorman <> | Subject | Re: [patch 7/8] mm: vmscan: compaction works against zones, not lruvecs |
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On Wed, Dec 12, 2012 at 04:43:39PM -0500, Johannes Weiner wrote: > The restart logic for when reclaim operates back to back with > compaction is currently applied on the lruvec level. But this does > not make sense, because the container of interest for compaction is a > zone as a whole, not the zone pages that are part of a certain memory > cgroup. > > Negative impact is bounded. For one, the code checks that the lruvec > has enough reclaim candidates, so it does not risk getting stuck on a > condition that can not be fulfilled. And the unfairness of hammering > on one particular memory cgroup to make progress in a zone will be > amortized by the round robin manner in which reclaim goes through the > memory cgroups. Still, this can lead to unnecessary allocation > latencies when the code elects to restart on a hard to reclaim or > small group when there are other, more reclaimable groups in the zone. > > Move this logic to the zone level and restart reclaim for all memory > cgroups in a zone when compaction requires more free pages from it. > > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Mel Gorman <mgorman@suse.de>
-- Mel Gorman SUSE Labs
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