Re: [PATCH 3/3] mm: vmscan: Use proportional scanning during direct reclaim and full scan at DEF_PRIORITY
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 Acked-by: Rik van Riel -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 3/3] mm: vmscan: Use proportional scanning during direct reclaim and full scan at DEF_PRIORITY
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 mgor...@suse.de Acked-by: Rik van Riel r...@redhat.com -- All rights reversed -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
