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| author | Vlastimil Babka <vbabka@suse.cz> | 2016-12-12 16:44:38 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-12 18:55:08 -0800 |
| commit | d5a187daf5856df9b997f9d208e5a7b64006eb2e (patch) | |
| tree | a9543d74a74fac2bc7a2c5bf378968e92e6fb9b4 /include | |
| parent | 46e8a3a08c23d07d0f21fabeed182b671af68c93 (diff) | |
| download | linux-d5a187daf5856df9b997f9d208e5a7b64006eb2e.tar.bz2 | |
mm, rmap: handle anon_vma_prepare() common case inline
anon_vma_prepare() is mostly a large "if (unlikely(...))" block, as the
expected common case is that an anon_vma already exists. We could turn
the condition around and return 0, but it also makes sense to do it
inline and avoid a call for the common case.
Bloat-o-meter naturally shows that inlining the check has some code size
costs:
add/remove: 1/1 grow/shrink: 4/0 up/down: 475/-373 (102)
function old new delta
__anon_vma_prepare - 359 +359
handle_mm_fault 2744 2796 +52
hugetlb_cow 1146 1170 +24
hugetlb_fault 2123 2145 +22
wp_page_copy 1469 1487 +18
anon_vma_prepare 373 - -373
Checking the asm however confirms that the hot paths now avoid a call,
which is moved away.
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20161116074005.22768-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/rmap.h | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h index b46bb5620a76..15321fb1df6b 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -137,11 +137,19 @@ static inline void anon_vma_unlock_read(struct anon_vma *anon_vma) * anon_vma helper functions. */ void anon_vma_init(void); /* create anon_vma_cachep */ -int anon_vma_prepare(struct vm_area_struct *); +int __anon_vma_prepare(struct vm_area_struct *); void unlink_anon_vmas(struct vm_area_struct *); int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *); int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *); +static inline int anon_vma_prepare(struct vm_area_struct *vma) +{ + if (likely(vma->anon_vma)) + return 0; + + return __anon_vma_prepare(vma); +} + static inline void anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next) { |