Commit a0647dc9 authored Nov 17, 2017 by David Rientjes Committed by Linus Torvalds Nov 17, 2017

mm, compaction: kcompactd should not ignore pageblock skip

Kcompactd is needlessly ignoring pageblock skip information.  It is
doing MIGRATE_SYNC_LIGHT compaction, which is no more powerful than
MIGRATE_SYNC compaction.

If compaction recently failed to isolate memory from a set of
pageblocks, there is nothing to indicate that kcompactd will be able to
do so, or that it is beneficial from attempting to isolate memory.

Use the pageblock skip hint to avoid rescanning pageblocks needlessly
until that information is reset.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1708151638550.106658@chino.kir.corp.google.com


Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 09af5cce

mm/compaction.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -1928,9 +1928,8 @@ static void kcompactd_do_work(pg_data_t *pgdat)
		.total_free_scanned = 0,
		.classzone_idx = pgdat->kcompactd_classzone_idx,
		.mode = MIGRATE_SYNC_LIGHT,
		.ignore_skip_hint = true,
		.ignore_skip_hint = false,
		.gfp_mask = GFP_KERNEL,

		};
		trace_mm_compaction_kcompactd_wake(pgdat->node_id, cc.order,
		cc.classzone_idx);

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