Messages in this thread | | | Date | Thu, 22 May 2014 12:04:12 -0400 | From | Rik van Riel <> | Subject | Re: [PATCH 3/3] mm: vmscan: Use proportional scanning during direct reclaim and full scan at DEF_PRIORITY |
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On 05/22/2014 05:09 AM, Mel Gorman wrote: > Commit "mm: vmscan: obey proportional scanning requirements for kswapd" > ensured that file/anon lists were scanned proportionally for reclaim from > kswapd but ignored it for direct reclaim. The intent was to minimse direct > reclaim latency but Yuanhan Liu pointer out that it substitutes one long > stall for many small stalls and distorts aging for normal workloads like > streaming readers/writers. Hugh Dickins pointed out that a side-effect of > the same commit was that when one LRU list dropped to zero that the entirety > of the other list was shrunk leading to excessive reclaim in memcgs. > This patch scans the file/anon lists proportionally for direct reclaim > to similarly age page whether reclaimed by kswapd or direct reclaim but > takes care to abort reclaim if one LRU drops to zero after reclaiming the > requested number of pages. >
> Note that there are fewer allocation stalls even though the amount > of direct reclaim scanning is very approximately the same. > > Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
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