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| author |   Matthew Wilcox <mawilcox@microsoft.com> | 2017-07-10 15:51:32 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-10 16:32:34 -0700 |
| commit | 2a98dc028f911a7c59c87d11d4eed6626be1605b (patch) | |
| tree | 6ef30a1615e1a374a442c18d1a92015264d32b0f /include/linux/bitmap.h | |
| parent | bitmap: optimise bitmap_set and bitmap_clear of a single bit (diff) | |
| download | linux-dev-2a98dc028f911a7c59c87d11d4eed6626be1605b.tar.xz linux-dev-2a98dc028f911a7c59c87d11d4eed6626be1605b.zip | |
include/linux/bitmap.h: turn bitmap_set and bitmap_clear into memset when possible
Several callers have constant 'start' and an 'nbits' that is a multiple
of 8, so we can turn them into calls to memset. We don't need the
entirety of 'start' and 'nbits' to be constant, we just need to know
whether they're divisible by 8.
Link: http://lkml.kernel.org/r/20170628153221.11322-4-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
| -rw-r--r-- | include/linux/bitmap.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 4e0f0c8167af..c04c9d155e59 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -319,6 +319,9 @@ static __always_inline void bitmap_set(unsigned long *map, unsigned int start, { if (__builtin_constant_p(nbits) && nbits == 1) __set_bit(start, map); + else if (__builtin_constant_p(start & 7) && IS_ALIGNED(start, 8) && + __builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8)) + memset((char *)map + start / 8, 0xff, nbits / 8); else __bitmap_set(map, start, nbits); } @@ -328,6 +331,9 @@ static __always_inline void bitmap_clear(unsigned long *map, unsigned int start, { if (__builtin_constant_p(nbits) && nbits == 1) __clear_bit(start, map); + else if (__builtin_constant_p(start & 7) && IS_ALIGNED(start, 8) && + __builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8)) + memset((char *)map + start / 8, 0, nbits / 8); else __bitmap_clear(map, start, nbits); } |