The patch titled
Subject: bitmap: Use memcmp optimisation in more situations
has been added to the -mm tree. Its filename is
bitmap-use-memcmp-optimisation-in-more-situations.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/bitmap-use-memcmp-optimisation-in-more-situations.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/bitmap-use-memcmp-optimisation-in-more-situations.patch
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------------------------------------------------------
From: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Subject: bitmap: Use memcmp optimisation in more situations
Commit 7dd968163f ("bitmap: bitmap_equal memcmp optimization") was
rather more restrictive than necessary; we can use memcmp() to implement
bitmap_equal() as long as the number of bits can be proved to be a
multiple of 8. And architectures other than s390 may be able to make
good use of this optimisation.
Link: http://lkml.kernel.org/r/20170628153221.11322-5-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Acked-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
---
1 file changed, 1 insertion(+), 3 deletions(-)
index c04c9d155e59..5797ca6fdfe2 100644
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/bitmap.h | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff -puN include/linux/bitmap.h~bitmap-use-memcmp-optimisation-in-more-situations include/linux/bitmap.h
--- a/include/linux/bitmap.h~bitmap-use-memcmp-optimisation-in-more-situations
+++ a/include/linux/bitmap.h
@@ -266,10 +266,8 @@ static inline int bitmap_equal(const uns
{
if (small_const_nbits(nbits))
return !((*src1 ^ *src2) & BITMAP_LAST_WORD_MASK(nbits));
-#ifdef CONFIG_S390
- if (__builtin_constant_p(nbits) && (nbits % BITS_PER_LONG) == 0)
+ if (__builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8))
return !memcmp(src1, src2, nbits / 8);
-#endif
return __bitmap_equal(src1, src2, nbits);
}
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
replace-memfmt-with-string_get_size.patch
bitmap-use-memcmp-optimisation-in-more-situations.patch
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