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authorVlastimil Babka <vbabka@suse.cz>2016-12-12 16:44:38 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-12-12 18:55:08 -0800
commitd5a187daf5856df9b997f9d208e5a7b64006eb2e (patch)
treea9543d74a74fac2bc7a2c5bf378968e92e6fb9b4 /include/linux/rmap.h
parent46e8a3a08c23d07d0f21fabeed182b671af68c93 (diff)
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/linux/rmap.h')
-rw-r--r--include/linux/rmap.h10
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)
{