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author | Vlastimil Babka <vbabka@suse.cz> | 2016-12-12 16:44:38 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-12 18:55:08 -0800 |
commit | d5a187daf5856df9b997f9d208e5a7b64006eb2e (patch) | |
tree | a9543d74a74fac2bc7a2c5bf378968e92e6fb9b4 /mm/page_alloc.c | |
parent | 46e8a3a08c23d07d0f21fabeed182b671af68c93 (diff) | |
download | lwn-d5a187daf5856df9b997f9d208e5a7b64006eb2e.tar.gz lwn-d5a187daf5856df9b997f9d208e5a7b64006eb2e.zip |
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 'mm/page_alloc.c')
0 files changed, 0 insertions, 0 deletions