From: David Rientjes <rientjes@google.com> To: Vlastimil Babka <vbabka@suse.cz> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, Greg Thelen <gthelen@google.com>, Minchan Kim <minchan@kernel.org>, Mel Gorman <mgorman@suse.de>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Michal Nazarewicz <mina86@mina86.com>, Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>, Christoph Lameter <cl@linux.com>, Rik van Riel <riel@redhat.com> Subject: Re: [RFC PATCH 6/6] mm, compaction: don't migrate in blocks that cannot be fully compacted in async direct compaction Date: Wed, 4 Jun 2014 17:08:59 -0700 (PDT) [thread overview] Message-ID: <alpine.DEB.2.02.1406041705140.22536@chino.kir.corp.google.com> (raw) In-Reply-To: <1401898310-14525-6-git-send-email-vbabka@suse.cz> On Wed, 4 Jun 2014, Vlastimil Babka wrote: > In direct compaction, we want to allocate the high-order page as soon as > possible, so migrating from a block of pages that contains also unmigratable > pages just adds to allocation latency. > The title of the patch in the subject line should probably be reworded since it implies we never isolate from blocks that cannot become completely free and what you're really doing is skipping cc->order aligned pages. > This patch therefore makes the migration scanner skip to the next cc->order > aligned block of pages as soon as it cannot isolate a non-free page. Everything > isolated up to that point is put back. > > In this mode, the nr_isolated limit to COMPACT_CLUSTER_MAX is not observed, > allowing the scanner to scan the whole block at once, instead of migrating > COMPACT_CLUSTER_MAX pages and then finding an unmigratable page in the next > call. This might however have some implications on too_many_isolated. > > Also in this RFC PATCH, the "skipping mode" is tied to async migration mode, > which is not optimal. What we most probably want is skipping in direct > compactions, but not from kswapd and hugepaged. > > In very preliminary tests, this has reduced migrate_scanned, isolations and > migrations by about 10%, while the success rate of stress-highalloc mmtests > actually improved a bit. > Ok, so this obsoletes my patchseries that did something similar. I hope you can rebase this set on top of linux-next and then propose it formally without the RFC tag. We also need to discuss the scheduling heuristics, the reliance on need_resched(), to abort async compaction. In testing, we actualy sometimes see 2-3 pageblocks scanned before terminating and thp has a very little chance of being allocated. At the same time, if we try to fault 64MB of anon memory in and each of the 32 calls to compaction are expensive but don't result in an order-9 page, we see very lengthy fault latency. I think it would be interesting to consider doing async compaction deferral up to 1 << COMPACT_MAX_DEFER_SHIFT after a sysctl-configurable amount of memory is scanned, at least for thp, and remove the scheduling heuristic entirely.
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From: David Rientjes <rientjes@google.com> To: Vlastimil Babka <vbabka@suse.cz> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, Greg Thelen <gthelen@google.com>, Minchan Kim <minchan@kernel.org>, Mel Gorman <mgorman@suse.de>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Michal Nazarewicz <mina86@mina86.com>, Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>, Christoph Lameter <cl@linux.com>, Rik van Riel <riel@redhat.com> Subject: Re: [RFC PATCH 6/6] mm, compaction: don't migrate in blocks that cannot be fully compacted in async direct compaction Date: Wed, 4 Jun 2014 17:08:59 -0700 (PDT) [thread overview] Message-ID: <alpine.DEB.2.02.1406041705140.22536@chino.kir.corp.google.com> (raw) In-Reply-To: <1401898310-14525-6-git-send-email-vbabka@suse.cz> On Wed, 4 Jun 2014, Vlastimil Babka wrote: > In direct compaction, we want to allocate the high-order page as soon as > possible, so migrating from a block of pages that contains also unmigratable > pages just adds to allocation latency. > The title of the patch in the subject line should probably be reworded since it implies we never isolate from blocks that cannot become completely free and what you're really doing is skipping cc->order aligned pages. > This patch therefore makes the migration scanner skip to the next cc->order > aligned block of pages as soon as it cannot isolate a non-free page. Everything > isolated up to that point is put back. > > In this mode, the nr_isolated limit to COMPACT_CLUSTER_MAX is not observed, > allowing the scanner to scan the whole block at once, instead of migrating > COMPACT_CLUSTER_MAX pages and then finding an unmigratable page in the next > call. This might however have some implications on too_many_isolated. > > Also in this RFC PATCH, the "skipping mode" is tied to async migration mode, > which is not optimal. What we most probably want is skipping in direct > compactions, but not from kswapd and hugepaged. > > In very preliminary tests, this has reduced migrate_scanned, isolations and > migrations by about 10%, while the success rate of stress-highalloc mmtests > actually improved a bit. > Ok, so this obsoletes my patchseries that did something similar. I hope you can rebase this set on top of linux-next and then propose it formally without the RFC tag. We also need to discuss the scheduling heuristics, the reliance on need_resched(), to abort async compaction. In testing, we actualy sometimes see 2-3 pageblocks scanned before terminating and thp has a very little chance of being allocated. At the same time, if we try to fault 64MB of anon memory in and each of the 32 calls to compaction are expensive but don't result in an order-9 page, we see very lengthy fault latency. I think it would be interesting to consider doing async compaction deferral up to 1 << COMPACT_MAX_DEFER_SHIFT after a sysctl-configurable amount of memory is scanned, at least for thp, and remove the scheduling heuristic entirely. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2014-06-05 0:09 UTC|newest] Thread overview: 267+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-05-01 0:45 [patch 1/2] mm, migration: add destination page freeing callback David Rientjes 2014-05-01 0:45 ` David Rientjes 2014-05-01 0:45 ` [patch 2/2] mm, compaction: return failed migration target pages back to freelist David Rientjes 2014-05-01 0:45 ` David Rientjes 2014-05-01 5:10 ` Naoya Horiguchi 2014-05-01 21:02 ` David Rientjes 2014-05-01 21:02 ` David Rientjes 2014-05-01 5:08 ` [patch 1/2] mm, migration: add destination page freeing callback Naoya Horiguchi [not found] ` <5361d71e.236ec20a.1b3d.ffffc8aeSMTPIN_ADDED_BROKEN@mx.google.com> 2014-05-01 21:02 ` David Rientjes 2014-05-01 21:02 ` David Rientjes 2014-05-01 21:35 ` [patch v2 1/4] " David Rientjes 2014-05-01 21:35 ` David Rientjes 2014-05-01 21:35 ` [patch v2 2/4] mm, compaction: return failed migration target pages back to freelist David Rientjes 2014-05-01 21:35 ` David Rientjes 2014-05-02 10:11 ` Mel Gorman 2014-05-02 10:11 ` Mel Gorman 2014-05-02 15:23 ` Vlastimil Babka 2014-05-02 15:23 ` Vlastimil Babka 2014-05-02 15:26 ` [PATCH] mm/compaction: do not count migratepages when unnecessary Vlastimil Babka 2014-05-06 21:18 ` Naoya Horiguchi [not found] ` <1399411134-k43fsr0p@n-horiguchi@ah.jp.nec.com> 2014-05-07 9:33 ` Vlastimil Babka 2014-05-07 9:33 ` Vlastimil Babka 2014-05-02 15:27 ` [PATCH 2/2] mm/compaction: avoid rescanning pageblocks in isolate_freepages Vlastimil Babka 2014-05-02 15:27 ` Vlastimil Babka 2014-05-06 22:19 ` Naoya Horiguchi [not found] ` <1399414778-xakujfb3@n-horiguchi@ah.jp.nec.com> 2014-05-07 9:22 ` Vlastimil Babka 2014-05-07 9:22 ` Vlastimil Babka 2014-05-02 15:29 ` [PATCH 1/2] mm/compaction: do not count migratepages when unnecessary Vlastimil Babka 2014-05-02 15:29 ` Vlastimil Babka 2014-05-01 21:35 ` [patch v2 3/4] mm, compaction: add per-zone migration pfn cache for async compaction David Rientjes 2014-05-01 21:35 ` David Rientjes 2014-05-05 9:34 ` Vlastimil Babka 2014-05-05 9:34 ` Vlastimil Babka 2014-05-05 9:51 ` David Rientjes 2014-05-05 9:51 ` David Rientjes 2014-05-05 14:24 ` Vlastimil Babka 2014-05-05 14:24 ` Vlastimil Babka 2014-05-06 0:29 ` David Rientjes 2014-05-06 0:29 ` David Rientjes 2014-05-06 11:52 ` Vlastimil Babka 2014-05-06 11:52 ` Vlastimil Babka 2014-05-01 21:35 ` [patch v2 4/4] mm, thp: do not perform sync compaction on pagefault David Rientjes 2014-05-01 21:35 ` David Rientjes 2014-05-02 10:22 ` Mel Gorman 2014-05-02 10:22 ` Mel Gorman 2014-05-02 11:22 ` David Rientjes 2014-05-02 11:22 ` David Rientjes 2014-05-02 11:58 ` Mel Gorman 2014-05-02 20:29 ` David Rientjes 2014-05-02 20:29 ` David Rientjes 2014-05-05 14:48 ` Vlastimil Babka 2014-05-05 14:48 ` Vlastimil Babka 2014-05-06 8:55 ` Mel Gorman 2014-05-06 8:55 ` Mel Gorman 2014-05-06 15:05 ` Vlastimil Babka 2014-05-06 15:05 ` Vlastimil Babka 2014-05-02 10:10 ` [patch v2 1/4] mm, migration: add destination page freeing callback Mel Gorman 2014-05-07 2:22 ` [patch v3 1/6] " David Rientjes 2014-05-07 2:22 ` David Rientjes 2014-05-07 2:22 ` [patch v3 2/6] mm, compaction: return failed migration target pages back to freelist David Rientjes 2014-05-07 2:22 ` David Rientjes 2014-05-07 14:14 ` Naoya Horiguchi 2014-05-07 21:15 ` Andrew Morton 2014-05-07 21:15 ` Andrew Morton 2014-05-07 21:21 ` David Rientjes 2014-05-07 21:21 ` David Rientjes 2014-05-12 8:35 ` Vlastimil Babka 2014-05-12 8:35 ` Vlastimil Babka 2014-05-07 21:39 ` Greg Thelen 2014-05-07 21:39 ` Greg Thelen 2014-05-12 8:37 ` Vlastimil Babka 2014-05-12 8:37 ` Vlastimil Babka 2014-05-07 2:22 ` [patch v3 3/6] mm, compaction: add per-zone migration pfn cache for async compaction David Rientjes 2014-05-07 2:22 ` David Rientjes 2014-05-07 9:34 ` Vlastimil Babka 2014-05-07 9:34 ` Vlastimil Babka 2014-05-07 20:56 ` Naoya Horiguchi 2014-05-07 2:22 ` [patch v3 4/6] mm, compaction: embed migration mode in compact_control David Rientjes 2014-05-07 2:22 ` David Rientjes 2014-05-07 9:55 ` Vlastimil Babka 2014-05-07 9:55 ` Vlastimil Babka 2014-05-07 10:36 ` [patch v4 " David Rientjes 2014-05-07 10:36 ` David Rientjes 2014-05-09 22:03 ` Andrew Morton 2014-05-09 22:03 ` Andrew Morton 2014-05-07 2:22 ` [patch v3 5/6] mm, thp: avoid excessive compaction latency during fault David Rientjes 2014-05-07 2:22 ` David Rientjes 2014-05-07 9:39 ` Mel Gorman 2014-05-07 9:39 ` Mel Gorman 2014-05-08 5:30 ` [patch -mm] mm, thp: avoid excessive compaction latency during fault fix David Rientjes 2014-05-08 5:30 ` David Rientjes 2014-05-13 10:00 ` Vlastimil Babka 2014-05-13 10:00 ` Vlastimil Babka 2014-05-22 2:49 ` David Rientjes 2014-05-22 2:49 ` David Rientjes 2014-05-22 8:43 ` Vlastimil Babka 2014-05-22 8:43 ` Vlastimil Babka 2014-05-07 2:22 ` [patch v3 6/6] mm, compaction: terminate async compaction when rescheduling David Rientjes 2014-05-07 2:22 ` David Rientjes 2014-05-07 9:41 ` Mel Gorman 2014-05-07 9:41 ` Mel Gorman 2014-05-07 12:09 ` [PATCH v2 1/2] mm/compaction: do not count migratepages when unnecessary Vlastimil Babka 2014-05-07 12:09 ` Vlastimil Babka 2014-05-07 12:09 ` [PATCH v2 2/2] mm/compaction: avoid rescanning pageblocks in isolate_freepages Vlastimil Babka 2014-05-07 12:09 ` Vlastimil Babka 2014-05-07 21:47 ` David Rientjes 2014-05-07 21:47 ` David Rientjes 2014-05-07 22:06 ` Naoya Horiguchi 2014-05-08 5:28 ` Joonsoo Kim 2014-05-08 5:28 ` Joonsoo Kim 2014-05-12 9:09 ` Vlastimil Babka 2014-05-12 9:09 ` Vlastimil Babka 2014-05-13 1:15 ` Joonsoo Kim 2014-05-13 1:15 ` Joonsoo Kim 2014-05-09 15:49 ` Michal Nazarewicz 2014-05-09 15:49 ` Michal Nazarewicz 2014-05-19 10:14 ` Vlastimil Babka 2014-05-19 10:14 ` Vlastimil Babka 2014-05-22 2:51 ` David Rientjes 2014-05-22 2:51 ` David Rientjes 2014-05-07 21:44 ` [PATCH v2 1/2] mm/compaction: do not count migratepages when unnecessary David Rientjes 2014-05-07 21:44 ` David Rientjes 2014-05-09 15:48 ` Michal Nazarewicz 2014-05-09 15:48 ` Michal Nazarewicz 2014-05-12 9:51 ` Vlastimil Babka 2014-05-12 9:51 ` Vlastimil Babka 2014-05-07 12:10 ` [patch v3 6/6] mm, compaction: terminate async compaction when rescheduling Vlastimil Babka 2014-05-07 12:10 ` Vlastimil Babka 2014-05-07 21:20 ` Andrew Morton 2014-05-07 21:20 ` Andrew Morton 2014-05-07 21:28 ` David Rientjes 2014-05-07 21:28 ` David Rientjes 2014-05-08 5:17 ` Joonsoo Kim 2014-05-08 5:17 ` Joonsoo Kim 2014-05-12 14:15 ` [PATCH] mm, compaction: properly signal and act upon lock and need_sched() contention Vlastimil Babka 2014-05-12 14:15 ` Vlastimil Babka 2014-05-12 15:34 ` Naoya Horiguchi [not found] ` <1399908847-ouuxeneo@n-horiguchi@ah.jp.nec.com> 2014-05-12 15:45 ` Vlastimil Babka 2014-05-12 15:45 ` Vlastimil Babka 2014-05-12 15:53 ` Naoya Horiguchi 2014-05-12 20:28 ` David Rientjes 2014-05-12 20:28 ` David Rientjes 2014-05-13 8:50 ` Vlastimil Babka 2014-05-13 8:50 ` Vlastimil Babka 2014-05-13 0:44 ` Joonsoo Kim 2014-05-13 0:44 ` Joonsoo Kim 2014-05-13 8:54 ` Vlastimil Babka 2014-05-13 8:54 ` Vlastimil Babka 2014-05-15 2:21 ` Joonsoo Kim 2014-05-15 2:21 ` Joonsoo Kim 2014-05-16 9:47 ` [PATCH v2] " Vlastimil Babka 2014-05-16 9:47 ` Vlastimil Babka 2014-05-16 17:33 ` Michal Nazarewicz 2014-05-16 17:33 ` Michal Nazarewicz 2014-05-19 23:37 ` Andrew Morton 2014-05-19 23:37 ` Andrew Morton 2014-05-21 14:13 ` Vlastimil Babka 2014-05-21 14:13 ` Vlastimil Babka 2014-05-21 20:11 ` Andrew Morton 2014-05-21 20:11 ` Andrew Morton 2014-05-22 3:20 ` compaction is still too expensive for thp (was: [PATCH v2] mm, compaction: properly signal and act upon lock and need_sched() contention) David Rientjes 2014-05-22 3:20 ` David Rientjes 2014-05-22 8:10 ` compaction is still too expensive for thp Vlastimil Babka 2014-05-22 8:10 ` Vlastimil Babka 2014-05-22 8:55 ` David Rientjes 2014-05-22 8:55 ` David Rientjes 2014-05-22 12:03 ` Vlastimil Babka 2014-05-22 12:03 ` Vlastimil Babka 2014-06-04 0:29 ` [patch -mm 1/3] mm: rename allocflags_to_migratetype for clarity David Rientjes 2014-06-04 0:29 ` David Rientjes 2014-06-04 0:29 ` [patch -mm 2/3] mm, compaction: pass gfp mask to compact_control David Rientjes 2014-06-04 0:29 ` David Rientjes 2014-06-04 0:30 ` [patch -mm 3/3] mm, compaction: avoid compacting memory for thp if pageblock cannot become free David Rientjes 2014-06-04 0:30 ` David Rientjes 2014-06-04 11:04 ` Mel Gorman 2014-06-04 11:04 ` Mel Gorman 2014-06-04 22:02 ` David Rientjes 2014-06-04 22:02 ` David Rientjes 2014-06-04 16:07 ` Vlastimil Babka 2014-06-04 16:07 ` Vlastimil Babka 2014-06-04 16:11 ` [RFC PATCH 1/6] mm, compaction: periodically drop lock and restore IRQs in scanners Vlastimil Babka 2014-06-04 16:11 ` Vlastimil Babka 2014-06-04 16:11 ` [RFC PATCH 2/6] mm, compaction: skip rechecks when lock was already held Vlastimil Babka 2014-06-04 16:11 ` Vlastimil Babka 2014-06-04 23:46 ` David Rientjes 2014-06-04 23:46 ` David Rientjes 2014-06-04 16:11 ` [RFC PATCH 3/6] mm, compaction: remember position within pageblock in free pages scanner Vlastimil Babka 2014-06-04 16:11 ` Vlastimil Babka 2014-06-04 16:11 ` [RFC PATCH 4/6] mm, compaction: skip buddy pages by their order in the migrate scanner Vlastimil Babka 2014-06-04 16:11 ` Vlastimil Babka 2014-06-05 0:02 ` David Rientjes 2014-06-05 0:02 ` David Rientjes 2014-06-05 9:24 ` Vlastimil Babka 2014-06-05 9:24 ` Vlastimil Babka 2014-06-05 21:30 ` David Rientjes 2014-06-05 21:30 ` David Rientjes 2014-06-06 7:20 ` Vlastimil Babka 2014-06-06 7:20 ` Vlastimil Babka 2014-06-09 9:09 ` David Rientjes 2014-06-09 9:09 ` David Rientjes 2014-06-09 11:35 ` Vlastimil Babka 2014-06-09 11:35 ` Vlastimil Babka 2014-06-09 22:25 ` David Rientjes 2014-06-09 22:25 ` David Rientjes 2014-06-10 7:26 ` Vlastimil Babka 2014-06-10 7:26 ` Vlastimil Babka 2014-06-10 23:54 ` David Rientjes 2014-06-10 23:54 ` David Rientjes 2014-06-11 12:18 ` Vlastimil Babka 2014-06-11 12:18 ` Vlastimil Babka 2014-06-12 0:21 ` David Rientjes 2014-06-12 0:21 ` David Rientjes 2014-06-12 11:56 ` Vlastimil Babka 2014-06-12 11:56 ` Vlastimil Babka 2014-06-12 21:48 ` David Rientjes 2014-06-12 21:48 ` David Rientjes 2014-06-04 16:11 ` [RFC PATCH 5/6] mm, compaction: try to capture the just-created high-order freepage Vlastimil Babka 2014-06-04 16:11 ` Vlastimil Babka 2014-06-04 16:11 ` [RFC PATCH 6/6] mm, compaction: don't migrate in blocks that cannot be fully compacted in async direct compaction Vlastimil Babka 2014-06-04 16:11 ` Vlastimil Babka 2014-06-05 0:08 ` David Rientjes [this message] 2014-06-05 0:08 ` David Rientjes 2014-06-05 15:38 ` Vlastimil Babka 2014-06-05 15:38 ` Vlastimil Babka 2014-06-05 21:38 ` David Rientjes 2014-06-05 21:38 ` David Rientjes 2014-06-06 7:33 ` Vlastimil Babka 2014-06-06 7:33 ` Vlastimil Babka 2014-06-09 9:06 ` David Rientjes 2014-06-09 9:06 ` David Rientjes 2014-06-12 12:18 ` Vlastimil Babka 2014-06-12 12:18 ` Vlastimil Babka 2014-06-04 23:39 ` [RFC PATCH 1/6] mm, compaction: periodically drop lock and restore IRQs in scanners David Rientjes 2014-06-04 23:39 ` David Rientjes 2014-06-05 9:05 ` Vlastimil Babka 2014-06-05 9:05 ` Vlastimil Babka 2014-05-22 23:49 ` [PATCH v2] mm, compaction: properly signal and act upon lock and need_sched() contention Kevin Hilman 2014-05-22 23:49 ` Kevin Hilman 2014-05-23 2:48 ` Shawn Guo 2014-05-23 2:48 ` Shawn Guo 2014-05-23 2:48 ` Shawn Guo 2014-05-23 8:34 ` Vlastimil Babka 2014-05-23 8:34 ` Vlastimil Babka 2014-05-23 8:34 ` Vlastimil Babka 2014-05-23 10:49 ` Shawn Guo 2014-05-23 10:49 ` Shawn Guo 2014-05-23 10:49 ` Shawn Guo 2014-05-23 15:07 ` Kevin Hilman 2014-05-23 15:07 ` Kevin Hilman 2014-05-23 15:07 ` Kevin Hilman 2014-05-30 16:59 ` Stephen Warren 2014-05-30 16:59 ` Stephen Warren 2014-05-30 16:59 ` Stephen Warren 2014-06-02 13:35 ` Fabio Estevam 2014-06-02 13:35 ` Fabio Estevam 2014-06-02 13:35 ` Fabio Estevam 2014-06-02 14:33 ` [PATCH -mm] mm, compaction: properly signal and act upon lock and need_sched() contention - fix Vlastimil Babka 2014-06-02 14:33 ` Vlastimil Babka 2014-06-02 14:33 ` Vlastimil Babka 2014-06-02 15:18 ` Fabio Estevam 2014-06-02 15:18 ` Fabio Estevam 2014-06-02 15:18 ` Fabio Estevam 2014-06-02 20:09 ` David Rientjes 2014-06-02 20:09 ` David Rientjes 2014-06-02 20:09 ` David Rientjes 2014-05-02 13:16 ` [patch 1/2] mm, migration: add destination page freeing callback Vlastimil Babka 2014-05-02 13:16 ` Vlastimil Babka
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