From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id A4EB36B004F for ; Wed, 29 Jul 2009 05:49:50 -0400 (EDT) Date: Wed, 29 Jul 2009 10:49:52 +0100 From: Mel Gorman Subject: [PATCH] page-allocator: Change migratetype for all pageblocks within a high-order page during __rmqueue_fallback Message-ID: <20090729094951.GA15102@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline Sender: owner-linux-mm@kvack.org To: akpm@linux-foundation.org Cc: apw@shadowen.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: 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 --- 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 caa9268..c158466 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 << (MAX_ORDER - 1 - start_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) @@ -834,8 +845,9 @@ __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); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org