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authorMel Gorman <mgorman@techsingularity.net>2016-05-19 17:13:21 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-19 19:12:14 -0700
commit175145748d00794369317070dd19ce12dd816241 (patch)
tree967976096168df6f2abec949fa99004182dae358 /include/linux/page-flags.h
parentd61f8590397480981f0d3ee7a2b38b5ea990db52 (diff)
mm, page_alloc: use new PageAnonHead helper in the free page fast path
The PageAnon check always checks for compound_head but this is a relatively expensive check if the caller already knows the page is a head page. This patch creates a helper and uses it in the page free path which only operates on head pages. With this patch and "Only check PageCompound for high-order pages", the performance difference on a page allocator microbenchmark is; 4.6.0-rc2 4.6.0-rc2 vanilla nocompound-v1r20 Min alloc-odr0-1 425.00 ( 0.00%) 417.00 ( 1.88%) Min alloc-odr0-2 313.00 ( 0.00%) 308.00 ( 1.60%) Min alloc-odr0-4 257.00 ( 0.00%) 253.00 ( 1.56%) Min alloc-odr0-8 224.00 ( 0.00%) 221.00 ( 1.34%) Min alloc-odr0-16 208.00 ( 0.00%) 205.00 ( 1.44%) Min alloc-odr0-32 199.00 ( 0.00%) 199.00 ( 0.00%) Min alloc-odr0-64 195.00 ( 0.00%) 193.00 ( 1.03%) Min alloc-odr0-128 192.00 ( 0.00%) 191.00 ( 0.52%) Min alloc-odr0-256 204.00 ( 0.00%) 200.00 ( 1.96%) Min alloc-odr0-512 213.00 ( 0.00%) 212.00 ( 0.47%) Min alloc-odr0-1024 219.00 ( 0.00%) 219.00 ( 0.00%) Min alloc-odr0-2048 225.00 ( 0.00%) 225.00 ( 0.00%) Min alloc-odr0-4096 230.00 ( 0.00%) 231.00 ( -0.43%) Min alloc-odr0-8192 235.00 ( 0.00%) 234.00 ( 0.43%) Min alloc-odr0-16384 235.00 ( 0.00%) 234.00 ( 0.43%) Min free-odr0-1 215.00 ( 0.00%) 191.00 ( 11.16%) Min free-odr0-2 152.00 ( 0.00%) 136.00 ( 10.53%) Min free-odr0-4 119.00 ( 0.00%) 107.00 ( 10.08%) Min free-odr0-8 106.00 ( 0.00%) 96.00 ( 9.43%) Min free-odr0-16 97.00 ( 0.00%) 87.00 ( 10.31%) Min free-odr0-32 91.00 ( 0.00%) 83.00 ( 8.79%) Min free-odr0-64 89.00 ( 0.00%) 81.00 ( 8.99%) Min free-odr0-128 88.00 ( 0.00%) 80.00 ( 9.09%) Min free-odr0-256 106.00 ( 0.00%) 95.00 ( 10.38%) Min free-odr0-512 116.00 ( 0.00%) 111.00 ( 4.31%) Min free-odr0-1024 125.00 ( 0.00%) 118.00 ( 5.60%) Min free-odr0-2048 133.00 ( 0.00%) 126.00 ( 5.26%) Min free-odr0-4096 136.00 ( 0.00%) 130.00 ( 4.41%) Min free-odr0-8192 138.00 ( 0.00%) 130.00 ( 5.80%) Min free-odr0-16384 137.00 ( 0.00%) 130.00 ( 5.11%) There is a sizable boost to the free allocator performance. While there is an apparent boost on the allocation side, it's likely a co-incidence or due to the patches slightly reducing cache footprint. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/page-flags.h')
-rw-r--r--include/linux/page-flags.h7
1 files changed, 6 insertions, 1 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 6b052aa7b5b7..a61e06e5fbce 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -371,10 +371,15 @@ PAGEFLAG(Idle, idle, PF_ANY)
#define PAGE_MAPPING_KSM 2
#define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM)
+static __always_inline int PageAnonHead(struct page *page)
+{
+ return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
+}
+
static __always_inline int PageAnon(struct page *page)
{
page = compound_head(page);
- return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
+ return PageAnonHead(page);
}
#ifdef CONFIG_KSM