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/[email protected]
Signed-off-by: Vlastimil Babka <[email protected]>
Reviewed-by: Anshuman Khandual <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Mel Gorman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 65876fe..46c30fa 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);
