From 16867664936e32423375bf44d240f440fff194cb Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Wed, 3 Jun 2020 15:58:42 -0700 Subject: mm,page_alloc,cma: conditionally prefer cma pageblocks for movable allocations Currently a cma area is barely used by the page allocator because it's used only as a fallback from movable, however kswapd tries hard to make sure that the fallback path isn't used. This results in a system evicting memory and pushing data into swap, while lots of CMA memory is still available. This happens despite the fact that alloc_contig_range is perfectly capable of moving any movable allocations out of the way of an allocation. To effectively use the cma area let's alter the rules: if the zone has more free cma pages than the half of total free pages in the zone, use cma pageblocks first and fallback to movable blocks in the case of failure. [guro@fb.com: ifdef the cma-specific code] Link: http://lkml.kernel.org/r/20200311225832.GA178154@carbon.DHCP.thefacebook.com Co-developed-by: Rik van Riel Signed-off-by: Roman Gushchin Signed-off-by: Rik van Riel Signed-off-by: Andrew Morton Acked-by: Vlastimil Babka Acked-by: Minchan Kim Cc: Qian Cai Cc: Mel Gorman Cc: Anshuman Khandual Cc: Joonsoo Kim Link: http://lkml.kernel.org/r/20200306150102.3e77354b@imladris.surriel.com Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'mm/page_alloc.c') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index cbe73a5610a1..5207a9e86388 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2752,6 +2752,20 @@ __rmqueue(struct zone *zone, unsigned int order, int migratetype, { struct page *page; +#ifdef CONFIG_CMA + /* + * Balance movable allocations between regular and CMA areas by + * allocating from CMA when over half of the zone's free memory + * is in the CMA area. + */ + if (migratetype == MIGRATE_MOVABLE && + zone_page_state(zone, NR_FREE_CMA_PAGES) > + zone_page_state(zone, NR_FREE_PAGES) / 2) { + page = __rmqueue_cma_fallback(zone, order); + if (page) + return page; + } +#endif retry: page = __rmqueue_smallest(zone, order, migratetype); if (unlikely(!page)) { -- cgit v1.2.3-59-g8ed1b