The patch titled
Subject: mm, page_alloc: use __dec_zone_state for order-0 page allocation
has been added to the -mm tree. Its filename is
mm-page_alloc-use-__dec_zone_state-for-order-0-page-allocation.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-use-__dec_zone_state-for-order-0-page-allocation.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-use-__dec_zone_state-for-order-0-page-allocation.patch
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------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Subject: mm, page_alloc: use __dec_zone_state for order-0 page allocation
__dec_zone_state is cheaper to use for removing an order-0 page as it has
fewer conditions to check.
The performance difference on a page allocator microbenchmark is;
4.6.0-rc2 4.6.0-rc2
optiter-v1r20 decstat-v1r20
Min alloc-odr0-1 382.00 ( 0.00%) 381.00 ( 0.26%)
Min alloc-odr0-2 282.00 ( 0.00%) 275.00 ( 2.48%)
Min alloc-odr0-4 233.00 ( 0.00%) 229.00 ( 1.72%)
Min alloc-odr0-8 203.00 ( 0.00%) 199.00 ( 1.97%)
Min alloc-odr0-16 188.00 ( 0.00%) 186.00 ( 1.06%)
Min alloc-odr0-32 182.00 ( 0.00%) 179.00 ( 1.65%)
Min alloc-odr0-64 177.00 ( 0.00%) 174.00 ( 1.69%)
Min alloc-odr0-128 175.00 ( 0.00%) 172.00 ( 1.71%)
Min alloc-odr0-256 184.00 ( 0.00%) 181.00 ( 1.63%)
Min alloc-odr0-512 197.00 ( 0.00%) 193.00 ( 2.03%)
Min alloc-odr0-1024 203.00 ( 0.00%) 201.00 ( 0.99%)
Min alloc-odr0-2048 209.00 ( 0.00%) 206.00 ( 1.44%)
Min alloc-odr0-4096 214.00 ( 0.00%) 212.00 ( 0.93%)
Min alloc-odr0-8192 218.00 ( 0.00%) 215.00 ( 1.38%)
Min alloc-odr0-16384 219.00 ( 0.00%) 216.00 ( 1.37%)
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN mm/page_alloc.c~mm-page_alloc-use-__dec_zone_state-for-order-0-page-allocation mm/page_alloc.c
--- a/mm/page_alloc.c~mm-page_alloc-use-__dec_zone_state-for-order-0-page-allocation
+++ a/mm/page_alloc.c
@@ -2444,6 +2444,7 @@ struct page *buffered_rmqueue(struct zon
else
page = list_first_entry(list, struct page, lru);
+ __dec_zone_state(zone, NR_ALLOC_BATCH);
list_del(&page->lru);
pcp->count--;
} else {
@@ -2465,11 +2466,11 @@ struct page *buffered_rmqueue(struct zon
spin_unlock(&zone->lock);
if (!page)
goto failed;
+ __mod_zone_page_state(zone, NR_ALLOC_BATCH, -(1 << order));
__mod_zone_freepage_state(zone, -(1 << order),
get_pcppage_migratetype(page));
}
- __mod_zone_page_state(zone, NR_ALLOC_BATCH, -(1 << order));
if (atomic_long_read(&zone->vm_stat[NR_ALLOC_BATCH]) <= 0 &&
!test_bit(ZONE_FAIR_DEPLETED, &zone->flags))
set_bit(ZONE_FAIR_DEPLETED, &zone->flags);
_
Patches currently in -mm which might be from mgorman@xxxxxxxxxxxxxxxxxxx are
mm-page_alloc-only-check-pagecompound-for-high-order-pages.patch
mm-page_alloc-use-new-pageanonhead-helper-in-the-free-page-fast-path.patch
mm-page_alloc-reduce-branches-in-zone_statistics.patch
mm-page_alloc-inline-zone_statistics.patch
mm-page_alloc-inline-the-fast-path-of-the-zonelist-iterator.patch
mm-page_alloc-use-__dec_zone_state-for-order-0-page-allocation.patch
mm-page_alloc-avoid-unnecessary-zone-lookups-during-pageblock-operations.patch
mm-page_alloc-convert-alloc_flags-to-unsigned.patch
mm-page_alloc-convert-nr_fair_skipped-to-bool.patch
mm-page_alloc-remove-unnecessary-local-variable-in-get_page_from_freelist.patch
mm-page_alloc-remove-unnecessary-initialisation-in-get_page_from_freelist.patch
mm-page_alloc-remove-redundant-check-for-empty-zonelist.patch
mm-page_alloc-simplify-last-cpupid-reset.patch
mm-page_alloc-move-might_sleep_if-check-to-the-allocator-slowpath.patch
mm-page_alloc-move-__gfp_hardwall-modifications-out-of-the-fastpath.patch
mm-page_alloc-check-once-if-a-zone-has-isolated-pageblocks.patch
mm-page_alloc-shorten-the-page-allocator-fast-path.patch
mm-page_alloc-reduce-cost-of-fair-zone-allocation-policy-retry.patch
mm-page_alloc-shortcut-watermark-checks-for-order-0-pages.patch
mm-page_alloc-avoid-looking-up-the-first-zone-in-a-zonelist-twice.patch
mm-page_alloc-remove-field-from-alloc_context.patch
mm-page_alloc-check-multiple-page-fields-with-a-single-branch.patch
mm-page_alloc-remove-unnecessary-variable-from-free_pcppages_bulk.patch
mm-page_alloc-inline-pageblock-lookup-in-page-free-fast-paths.patch
mm-page_alloc-defer-debugging-checks-of-freed-pages-until-a-pcp-drain.patch
mm-page_alloc-defer-debugging-checks-of-pages-allocated-from-the-pcp.patch
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