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. Signed-off-by: Vlastimil Babka <[email protected]> Acked-by: Michal Hocko <[email protected]> Reviewed-by: Anshuman Khandual <[email protected]> --- 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 05068adf9007..407e5d89ad2e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3900,9 +3900,10 @@ 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); -- 2.11.0
