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authorMel Gorman <mgorman@techsingularity.net>2019-03-05 15:45:31 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-05 21:07:17 -0800
commitdbe2d4e4f12e07c6a2215e3603a5f77056323081 (patch)
tree03ac02c91b3900b20c999bbc48c064f5c584afd6 /mm/internal.h
parentd097a6f63522547dfc7c75c7084a05b6a7f9e838 (diff)
mm, compaction: round-robin the order while searching the free lists for a target
As compaction proceeds and creates high-order blocks, the free list search gets less efficient as the larger blocks are used as compaction targets. Eventually, the larger blocks will be behind the migration scanner for partially migrated pageblocks and the search fails. This patch round-robins what orders are searched so that larger blocks can be ignored and find smaller blocks that can be used as migration targets. The overall impact was small on 1-socket but it avoids corner cases where the migration/free scanners meet prematurely or situations where many of the pageblocks encountered by the free scanner are almost full instead of being properly packed. Previous testing had indicated that without this patch there were occasional large spikes in the free scanner without this patch. [dan.carpenter@oracle.com: fix static checker warning] Link: http://lkml.kernel.org/r/20190118175136.31341-20-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/internal.h')
-rw-r--r--mm/internal.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/internal.h b/mm/internal.h
index d5b999e5eb5f..31bb0be6fd52 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -192,7 +192,8 @@ struct compact_control {
struct zone *zone;
unsigned long total_migrate_scanned;
unsigned long total_free_scanned;
- unsigned int fast_search_fail; /* failures to use free list searches */
+ unsigned short fast_search_fail;/* failures to use free list searches */
+ short search_order; /* order to start a fast search at */
const gfp_t gfp_mask; /* gfp mask of a direct compactor */
int order; /* order a direct compactor needs */
int migratetype; /* migratetype of direct compactor */