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Commit b9f00e14 authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
Browse files

mm, page_alloc: reduce branches in zone_statistics 



zone_statistics has more branches than it really needs to take an
unlikely GFP flag into account.  Reduce the number and annotate the
unlikely flag.

The performance difference on a page allocator microbenchmark is;

                                             4.6.0-rc2                  4.6.0-rc2
                                      nocompound-v1r10           statbranch-v1r10
  Min      alloc-odr0-1               417.00 (  0.00%)           419.00 ( -0.48%)
  Min      alloc-odr0-2               308.00 (  0.00%)           305.00 (  0.97%)
  Min      alloc-odr0-4               253.00 (  0.00%)           250.00 (  1.19%)
  Min      alloc-odr0-8               221.00 (  0.00%)           219.00 (  0.90%)
  Min      alloc-odr0-16              205.00 (  0.00%)           203.00 (  0.98%)
  Min      alloc-odr0-32              199.00 (  0.00%)           195.00 (  2.01%)
  Min      alloc-odr0-64              193.00 (  0.00%)           191.00 (  1.04%)
  Min      alloc-odr0-128             191.00 (  0.00%)           189.00 (  1.05%)
  Min      alloc-odr0-256             200.00 (  0.00%)           198.00 (  1.00%)
  Min      alloc-odr0-512             212.00 (  0.00%)           210.00 (  0.94%)
  Min      alloc-odr0-1024            219.00 (  0.00%)           216.00 (  1.37%)
  Min      alloc-odr0-2048            225.00 (  0.00%)           221.00 (  1.78%)
  Min      alloc-odr0-4096            231.00 (  0.00%)           227.00 (  1.73%)
  Min      alloc-odr0-8192            234.00 (  0.00%)           232.00 (  0.85%)
  Min      alloc-odr0-16384           234.00 (  0.00%)           232.00 (  0.85%)

Signed-off-by: default avatarMel Gorman <mgorman@techsingularity.net>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 17514574

mm/vmstat.c

+10 −6
Original line number Diff line number Diff line
@@ -581,17 +581,21 @@ void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset) 
 */

void zone_statistics(struct zone *preferred_zone, struct zone *z, gfp_t flags)

{

	if (z->zone_pgdat == preferred_zone->zone_pgdat) {

	int local_nid = numa_node_id();

	enum zone_stat_item local_stat = NUMA_LOCAL;



	if (unlikely(flags & __GFP_OTHER_NODE)) {

		local_stat = NUMA_OTHER;

		local_nid = preferred_zone->node;

	}



	if (z->node == local_nid) {

		__inc_zone_state(z, NUMA_HIT);

		__inc_zone_state(z, local_stat);

	} else {

		__inc_zone_state(z, NUMA_MISS);

		__inc_zone_state(preferred_zone, NUMA_FOREIGN);

	}

	if (z->node == ((flags & __GFP_OTHER_NODE) ?

			preferred_zone->node : numa_node_id()))

		__inc_zone_state(z, NUMA_LOCAL);

	else

		__inc_zone_state(z, NUMA_OTHER);

}



/*