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authorVlastimil Babka <vbabka@suse.cz>2017-05-08 15:54:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-05-08 17:15:10 -0700
commit02aa0cdd72483c6dd436ed24d1000f86e0038d28 (patch)
tree0cdf8eec0c5f69b59d7284519ae6b44aab6d6aed /include
parent3bc48f96cf11ce8699e419d5e47ae0d456403274 (diff)
mm, page_alloc: count movable pages when stealing from pageblock
When stealing pages from pageblock of a different migratetype, we count how many free pages were stolen, and change the pageblock's migratetype if more than half of the pageblock was free. This might be too conservative, as there might be other pages that are not free, but were allocated with the same migratetype as our allocation requested. While we cannot determine the migratetype of allocated pages precisely (at least without the page_owner functionality enabled), we can count pages that compaction would try to isolate for migration - those are either on LRU or __PageMovable(). The rest can be assumed to be MIGRATE_RECLAIMABLE or MIGRATE_UNMOVABLE, which we cannot easily distinguish. This counting can be done as part of free page stealing with little additional overhead. The page stealing code is changed so that it considers free pages plus pages of the "good" migratetype for the decision whether to change pageblock's migratetype. The result should be more accurate migratetype of pageblocks wrt the actual pages in the pageblocks, when stealing from semi-occupied pageblocks. This should help the efficiency of page grouping by mobility. In testing based on 4.9 kernel with stress-highalloc from mmtests configured for order-4 GFP_KERNEL allocations, this patch has reduced the number of unmovable allocations falling back to movable pageblocks by 47%. The number of movable allocations falling back to other pageblocks are increased by 55%, but these events don't cause permanent fragmentation, so the tradeoff should be positive. Later patches also offset the movable fallback increase to some extent. [akpm@linux-foundation.org: merge fix] Link: http://lkml.kernel.org/r/20170307131545.28577-5-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/page-isolation.h5
1 files changed, 1 insertions, 4 deletions
diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
index 047d64706f2a..d4cd2014fa6f 100644
--- a/include/linux/page-isolation.h
+++ b/include/linux/page-isolation.h
@@ -33,10 +33,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
bool skip_hwpoisoned_pages);
void set_pageblock_migratetype(struct page *page, int migratetype);
int move_freepages_block(struct zone *zone, struct page *page,
- int migratetype);
-int move_freepages(struct zone *zone,
- struct page *start_page, struct page *end_page,
- int migratetype);
+ int migratetype, int *num_movable);
/*
* Changes migrate type in [start_pfn, end_pfn) to be MIGRATE_ISOLATE.