From: Vlastimil Babka <vbabka@suse.cz> To: linux-mm@kvack.org, Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>, David Rientjes <rientjes@google.com>, Mel Gorman <mgorman@techsingularity.net>, linux-kernel@vger.kernel.org, kernel-team@fb.com, Vlastimil Babka <vbabka@suse.cz> Subject: [PATCH v2 02/10] mm, compaction: remove redundant watermark check in compact_finished() Date: Fri, 10 Feb 2017 18:23:35 +0100 [thread overview] Message-ID: <20170210172343.30283-3-vbabka@suse.cz> (raw) In-Reply-To: <20170210172343.30283-1-vbabka@suse.cz> When detecting whether compaction has succeeded in forming a high-order page, __compact_finished() employs a watermark check, followed by an own search for a suitable page in the freelists. This is not ideal for two reasons: - The watermark check also searches high-order freelists, but has a less strict criteria wrt fallback. It's therefore redundant and waste of cycles. This was different in the past when high-order watermark check attempted to apply reserves to high-order pages. - The watermark check might actually fail due to lack of order-0 pages. Compaction can't help with that, so there's no point in continuing because of that. It's possible that high-order page still exists and it terminates. This patch therefore removes the watermark check. This should save some cycles and terminate compaction sooner in some cases. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> --- mm/compaction.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 0409a4ad6ea1..fc88e7b6fe37 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1291,7 +1291,6 @@ static enum compact_result __compact_finished(struct zone *zone, struct compact_ const int migratetype) { unsigned int order; - unsigned long watermark; if (cc->contended || fatal_signal_pending(current)) return COMPACT_CONTENDED; @@ -1319,13 +1318,6 @@ static enum compact_result __compact_finished(struct zone *zone, struct compact_ if (is_via_compact_memory(cc->order)) return COMPACT_CONTINUE; - /* Compaction run is not finished if the watermark is not met */ - watermark = zone->watermark[cc->alloc_flags & ALLOC_WMARK_MASK]; - - if (!zone_watermark_ok(zone, cc->order, watermark, cc->classzone_idx, - cc->alloc_flags)) - return COMPACT_CONTINUE; - /* Direct compactor: Is a suitable page free? */ for (order = cc->order; order < MAX_ORDER; order++) { struct free_area *area = &zone->free_area[order]; -- 2.11.0
WARNING: multiple messages have this Message-ID (diff)
From: Vlastimil Babka <vbabka@suse.cz> To: linux-mm@kvack.org, Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>, David Rientjes <rientjes@google.com>, Mel Gorman <mgorman@techsingularity.net>, linux-kernel@vger.kernel.org, kernel-team@fb.com, Vlastimil Babka <vbabka@suse.cz> Subject: [PATCH v2 02/10] mm, compaction: remove redundant watermark check in compact_finished() Date: Fri, 10 Feb 2017 18:23:35 +0100 [thread overview] Message-ID: <20170210172343.30283-3-vbabka@suse.cz> (raw) In-Reply-To: <20170210172343.30283-1-vbabka@suse.cz> When detecting whether compaction has succeeded in forming a high-order page, __compact_finished() employs a watermark check, followed by an own search for a suitable page in the freelists. This is not ideal for two reasons: - The watermark check also searches high-order freelists, but has a less strict criteria wrt fallback. It's therefore redundant and waste of cycles. This was different in the past when high-order watermark check attempted to apply reserves to high-order pages. - The watermark check might actually fail due to lack of order-0 pages. Compaction can't help with that, so there's no point in continuing because of that. It's possible that high-order page still exists and it terminates. This patch therefore removes the watermark check. This should save some cycles and terminate compaction sooner in some cases. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> --- mm/compaction.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 0409a4ad6ea1..fc88e7b6fe37 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1291,7 +1291,6 @@ static enum compact_result __compact_finished(struct zone *zone, struct compact_ const int migratetype) { unsigned int order; - unsigned long watermark; if (cc->contended || fatal_signal_pending(current)) return COMPACT_CONTENDED; @@ -1319,13 +1318,6 @@ static enum compact_result __compact_finished(struct zone *zone, struct compact_ if (is_via_compact_memory(cc->order)) return COMPACT_CONTINUE; - /* Compaction run is not finished if the watermark is not met */ - watermark = zone->watermark[cc->alloc_flags & ALLOC_WMARK_MASK]; - - if (!zone_watermark_ok(zone, cc->order, watermark, cc->classzone_idx, - cc->alloc_flags)) - return COMPACT_CONTINUE; - /* Direct compactor: Is a suitable page free? */ for (order = cc->order; order < MAX_ORDER; order++) { struct free_area *area = &zone->free_area[order]; -- 2.11.0 -- 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:[~2017-02-10 19:13 UTC|newest] Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-02-10 17:23 [PATCH v2 00/10] try to reduce fragmenting fallbacks Vlastimil Babka 2017-02-10 17:23 ` Vlastimil Babka 2017-02-10 17:23 ` [PATCH v2 01/10] mm, compaction: reorder fields in struct compact_control Vlastimil Babka 2017-02-10 17:23 ` Vlastimil Babka 2017-02-13 10:49 ` Mel Gorman 2017-02-13 10:49 ` Mel Gorman 2017-02-14 16:33 ` Johannes Weiner 2017-02-14 16:33 ` Johannes Weiner 2017-02-10 17:23 ` Vlastimil Babka [this message] 2017-02-10 17:23 ` [PATCH v2 02/10] mm, compaction: remove redundant watermark check in compact_finished() Vlastimil Babka 2017-02-13 10:49 ` Mel Gorman 2017-02-13 10:49 ` Mel Gorman 2017-02-14 16:34 ` Johannes Weiner 2017-02-14 16:34 ` Johannes Weiner 2017-02-10 17:23 ` [PATCH v2 03/10] mm, page_alloc: split smallest stolen page in fallback Vlastimil Babka 2017-02-10 17:23 ` Vlastimil Babka 2017-02-13 10:51 ` Mel Gorman 2017-02-13 10:51 ` Mel Gorman 2017-02-13 10:54 ` Vlastimil Babka 2017-02-13 10:54 ` Vlastimil Babka 2017-02-14 16:59 ` Johannes Weiner 2017-02-14 16:59 ` Johannes Weiner 2017-02-10 17:23 ` [PATCH v2 04/10] mm, page_alloc: count movable pages when stealing from pageblock Vlastimil Babka 2017-02-10 17:23 ` Vlastimil Babka 2017-02-13 10:53 ` Mel Gorman 2017-02-13 10:53 ` Mel Gorman 2017-02-14 10:07 ` Xishi Qiu 2017-02-14 10:07 ` Xishi Qiu 2017-02-15 10:47 ` Vlastimil Babka 2017-02-15 10:47 ` Vlastimil Babka 2017-02-15 11:56 ` Xishi Qiu 2017-02-15 11:56 ` Xishi Qiu 2017-02-17 16:21 ` Vlastimil Babka 2017-02-17 16:21 ` Vlastimil Babka 2017-02-14 18:10 ` Johannes Weiner 2017-02-14 18:10 ` Johannes Weiner 2017-02-17 16:09 ` Vlastimil Babka 2017-02-17 16:09 ` Vlastimil Babka 2017-02-10 17:23 ` [PATCH v2 05/10] mm, compaction: change migrate_async_suitable() to suitable_migration_source() Vlastimil Babka 2017-02-10 17:23 ` Vlastimil Babka 2017-02-13 10:53 ` Mel Gorman 2017-02-13 10:53 ` Mel Gorman 2017-02-14 18:12 ` Johannes Weiner 2017-02-14 18:12 ` Johannes Weiner 2017-02-10 17:23 ` [PATCH v2 06/10] mm, compaction: add migratetype to compact_control Vlastimil Babka 2017-02-10 17:23 ` Vlastimil Babka 2017-02-13 10:53 ` Mel Gorman 2017-02-13 10:53 ` Mel Gorman 2017-02-14 18:15 ` Johannes Weiner 2017-02-14 18:15 ` Johannes Weiner 2017-02-10 17:23 ` [PATCH v2 07/10] mm, compaction: restrict async compaction to pageblocks of same migratetype Vlastimil Babka 2017-02-10 17:23 ` Vlastimil Babka 2017-02-13 10:56 ` Mel Gorman 2017-02-13 10:56 ` Mel Gorman 2017-02-14 20:10 ` Johannes Weiner 2017-02-14 20:10 ` Johannes Weiner 2017-02-17 16:32 ` Vlastimil Babka 2017-02-17 16:32 ` Vlastimil Babka 2017-02-17 17:39 ` Johannes Weiner 2017-02-17 17:39 ` Johannes Weiner 2017-02-10 17:23 ` [PATCH v2 08/10] mm, compaction: finish whole pageblock to reduce fragmentation Vlastimil Babka 2017-02-10 17:23 ` Vlastimil Babka 2017-02-13 10:57 ` Mel Gorman 2017-02-13 10:57 ` Mel Gorman 2017-02-16 11:44 ` Johannes Weiner 2017-02-16 11:44 ` Johannes Weiner 2017-02-10 17:23 ` [RFC v2 09/10] mm, page_alloc: disallow migratetype fallback in fastpath Vlastimil Babka 2017-02-10 17:23 ` Vlastimil Babka 2017-02-10 17:23 ` [RFC v2 10/10] mm, page_alloc: introduce MIGRATE_MIXED migratetype Vlastimil Babka 2017-02-10 17:23 ` Vlastimil Babka 2017-03-08 2:16 ` Yisheng Xie 2017-03-08 2:16 ` Yisheng Xie 2017-03-08 7:07 ` Vlastimil Babka 2017-03-08 7:07 ` Vlastimil Babka 2017-03-13 2:16 ` Yisheng Xie 2017-03-13 2:16 ` Yisheng Xie 2017-02-13 11:07 ` [PATCH v2 00/10] try to reduce fragmenting fallbacks Mel Gorman 2017-02-13 11:07 ` Mel Gorman 2017-02-15 14:29 ` Vlastimil Babka 2017-02-15 14:29 ` Vlastimil Babka 2017-02-15 16:11 ` Vlastimil Babka 2017-02-15 16:11 ` Vlastimil Babka 2017-02-15 20:11 ` Vlastimil Babka 2017-02-15 20:11 ` Vlastimil Babka 2017-02-16 15:12 ` Vlastimil Babka 2017-02-16 15:12 ` Vlastimil Babka 2017-02-17 15:24 ` Vlastimil Babka 2017-02-17 15:24 ` Vlastimil Babka 2017-02-20 12:30 ` Vlastimil Babka 2017-02-20 12:30 ` Vlastimil Babka 2017-02-23 16:01 ` Mel Gorman 2017-02-23 16:01 ` Mel Gorman
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