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Message-Id: <20170628153221.11322-5-willy@infradead.org>
Date: Wed, 28 Jun 2017 08:32:21 -0700
From: Matthew Wilcox <willy@...radead.org>
To: linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Matthew Wilcox <mawilcox@...rosoft.com>
Subject: [PATCH v2 4/4] bitmap: Use memcmp optimisation in more situations
From: Matthew Wilcox <mawilcox@...rosoft.com>
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.
Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
Acked-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
include/linux/bitmap.h | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index c04c9d155e59..5797ca6fdfe2 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -266,10 +266,8 @@ static inline int bitmap_equal(const unsigned long *src1,
{
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);
}
--
2.11.0
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