diff options
| author | Mel Gorman <mgorman@techsingularity.net> | 2016-05-20 02:13:21 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-05-20 04:12:14 +0200 |
| commit | 175145748d00794369317070dd19ce12dd816241 (patch) | |
| tree | 967976096168df6f2abec949fa99004182dae358 | |
| parent | mm, page_alloc: only check PageCompound for high-order pages (diff) | |
| download | linux-175145748d00794369317070dd19ce12dd816241.tar.xz linux-175145748d00794369317070dd19ce12dd816241.zip | |
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>
| -rw-r--r-- | include/linux/page-flags.h | 7 | ||||
| -rw-r--r-- | mm/page_alloc.c | 2 |
2 files changed, 7 insertions, 2 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 diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 087ba3e417ec..7be1ce8b6be0 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1048,7 +1048,7 @@ static bool free_pages_prepare(struct page *page, unsigned int order) bad += free_pages_check(page + i); } } - if (PageAnon(page)) + if (PageAnonHead(page)) page->mapping = NULL; bad += free_pages_check(page); if (bad) |