From 5104782011a12b04fe9cfaa6f1085bdcdedd79c4 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Fri, 24 Feb 2017 14:56:53 -0800 Subject: [PATCH] mm, page_alloc: don't check cpuset allowed twice in fast-path Since commit 682a3385e773 ("mm, page_alloc: inline the fast path of the zonelist iterator") we replace a NULL nodemask with cpuset_current_mems_allowed in the fast path, so that get_page_from_freelist() filters nodes allowed by the cpuset via for_next_zone_zonelist_nodemask(). In that case it's pointless to additionaly check __cpuset_zone_allowed() in each iteration, which we can avoid by not adding ALLOC_CPUSET to alloc_flags in that scenario. This saves some cycles in the allocator fast path on systems with one or more non-root cpuset configured. In the slow path, ALLOC_CPUSET is reset according to __alloc_pages_slowpath(). Without configured cpusets, this code is disabled by a static key. Link: http://lkml.kernel.org/r/20170124150511.5710-2-vbabka@suse.cz Signed-off-by: Vlastimil Babka Reviewed-by: Anshuman Khandual Acked-by: Michal Hocko Cc: Anshuman Khandual Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 65876feb86f3..46c30fa26acd 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3903,9 +3903,10 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order, if (cpusets_enabled()) { *alloc_mask |= __GFP_HARDWALL; - *alloc_flags |= ALLOC_CPUSET; if (!ac->nodemask) ac->nodemask = &cpuset_current_mems_allowed; + else + *alloc_flags |= ALLOC_CPUSET; } lockdep_trace_alloc(gfp_mask); -- 2.20.1