From 2f66a68f3fac2e94da360c342ff78ab45553f86c Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Mon, 21 Sep 2009 17:02:31 -0700 Subject: [PATCH] page-allocator: change migratetype for all pageblocks within a high-order page during __rmqueue_fallback When there are no pages of a target migratetype free, the page allocator selects a high-order block of another migratetype to allocate from. When the order of the page taken is greater than pageblock_order, all pageblocks within that high-order page should change migratetype so that pages are later freed to the correct free-lists. The current behaviour is that pageblocks change migratetype if the order being split matches the pageblock_order. When pageblock_order < MAX_ORDER-1, ownership is not changing correct and pages are being later freed to the incorrect list and this impacts fragmentation avoidance. This patch changes all pageblocks within the high-order page being split to the correct migratetype. Without the patch, allocation success rates for hugepages under stress were about 59% of physical memory on x86-64. With the patch applied, this goes up to 65%. Signed-off-by: Mel Gorman Cc: Andy Whitcroft Cc: KOSAKI Motohiro Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 9242d13f4ff3..20759803a64a 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -783,6 +783,17 @@ static int move_freepages_block(struct zone *zone, struct page *page, return move_freepages(zone, start_page, end_page, migratetype); } +static void change_pageblock_range(struct page *pageblock_page, + int start_order, int migratetype) +{ + int nr_pageblocks = 1 << (start_order - pageblock_order); + + while (nr_pageblocks--) { + set_pageblock_migratetype(pageblock_page, migratetype); + pageblock_page += pageblock_nr_pages; + } +} + /* Remove an element from the buddy allocator from the fallback list */ static inline struct page * __rmqueue_fallback(struct zone *zone, int order, int start_migratetype) @@ -836,8 +847,9 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype) list_del(&page->lru); rmv_page_order(page); - if (current_order == pageblock_order) - set_pageblock_migratetype(page, + /* Take ownership for orders >= pageblock_order */ + if (current_order >= pageblock_order) + change_pageblock_range(page, current_order, start_migratetype); expand(zone, page, order, current_order, area, migratetype); -- GitLab