From: Vlastimil Babka <vbabka@suse.cz>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Johannes Weiner <hannes@cmpxchg.org>,
Mel Gorman <mgorman@techsingularity.net>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
David Rientjes <rientjes@google.com>,
kernel-team@fb.com, Vlastimil Babka <vbabka@suse.cz>
Subject: [PATCH v3 2/8] mm, compaction: remove redundant watermark check in compact_finished()
Date: Tue, 7 Mar 2017 14:15:39 +0100 [thread overview]
Message-ID: <20170307131545.28577-3-vbabka@suse.cz> (raw)
In-Reply-To: <20170307131545.28577-1-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>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
---
mm/compaction.c | 8 --------
1 file changed, 8 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index 81e1eaa2a2cf..9222ff362f33 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1280,7 +1280,6 @@ 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;
@@ -1308,13 +1307,6 @@ 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];
--
2.12.0
--
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next prev parent reply other threads:[~2017-03-07 13:16 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-07 13:15 [PATCH v3 0/8] try to reduce fragmenting fallbacks Vlastimil Babka
2017-03-07 13:15 ` [PATCH v3 1/8] mm, compaction: reorder fields in struct compact_control Vlastimil Babka
2017-03-07 13:15 ` Vlastimil Babka [this message]
2017-03-16 1:30 ` [PATCH v3 2/8] mm, compaction: remove redundant watermark check in compact_finished() Joonsoo Kim
2017-03-29 15:30 ` Vlastimil Babka
2017-03-07 13:15 ` [PATCH v3 3/8] mm, page_alloc: split smallest stolen page in fallback Vlastimil Babka
2017-03-07 13:15 ` [PATCH v3 4/8] mm, page_alloc: count movable pages when stealing from pageblock Vlastimil Babka
2017-03-16 1:53 ` Joonsoo Kim
2017-03-29 15:49 ` Vlastimil Babka
2017-03-07 13:15 ` [PATCH v3 5/8] mm, compaction: change migrate_async_suitable() to suitable_migration_source() Vlastimil Babka
2017-03-07 13:15 ` [PATCH v3 6/8] mm, compaction: add migratetype to compact_control Vlastimil Babka
2017-03-07 13:15 ` [PATCH v3 7/8] mm, compaction: restrict async compaction to pageblocks of same migratetype Vlastimil Babka
2017-03-16 2:14 ` Joonsoo Kim
2017-03-29 16:06 ` Vlastimil Babka
2017-04-07 0:38 ` Joonsoo Kim
2017-05-04 6:12 ` Vlastimil Babka
2017-03-07 13:15 ` [PATCH v3 8/8] mm, compaction: finish whole pageblock to reduce fragmentation Vlastimil Babka
2017-03-16 2:18 ` Joonsoo Kim
2017-03-29 16:13 ` Vlastimil Babka
2017-03-08 16:46 ` [PATCH v3 0/8] try to reduce fragmenting fallbacks Johannes Weiner
2017-03-08 19:17 ` Vlastimil Babka
2017-03-16 18:34 ` Johannes Weiner
2017-03-17 18:29 ` Vlastimil Babka
2017-03-19 21:23 ` Johannes Weiner
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