| commit | ede9c697bc7513f210103fa77a9031e89726ae40 | |
| author | Eric Dumazet <dada1@cosmosbay.com> | |
| Tue, 29 Apr 2008 07:58:35 +0000 (29 00:58 -0700) | ||
| committer | Linus Torvalds <torvalds@linux-foundation.org> | |
| Tue, 29 Apr 2008 15:05:59 +0000 (29 08:05 -0700) | ||
| tree | a48eaac7da2877aa5600e5b4e99dedabd4b4b6fb | treesnapshot (tar.gz zip) |
| parent | cdac75e6f2fec9abc21d0abb4e5d80720eeebb10 | commitdiff |
Avoid divides in BITS_TO_LONGS
BITS_PER_LONG is a signed value (32 or 64)
DIV_ROUND_UP(nr, BITS_PER_LONG) performs signed arithmetic if "nr" is signed too.
Converting BITS_TO_LONGS(nr) to DIV_ROUND_UP(nr, BITS_PER_BYTE *
sizeof(long)) makes sure compiler can perform a right shift, even if "nr"
is a signed value, instead of an expensive integer divide.
Applying this patch saves 141 bytes on x86 when CONFIG_CC_OPTIMIZE_FOR_SIZE=y
and speedup bitmap operations.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
BITS_PER_LONG is a signed value (32 or 64)
DIV_ROUND_UP(nr, BITS_PER_LONG) performs signed arithmetic if "nr" is signed too.
Converting BITS_TO_LONGS(nr) to DIV_ROUND_UP(nr, BITS_PER_BYTE *
sizeof(long)) makes sure compiler can perform a right shift, even if "nr"
is a signed value, instead of an expensive integer divide.
Applying this patch saves 141 bytes on x86 when CONFIG_CC_OPTIMIZE_FOR_SIZE=y
and speedup bitmap operations.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| include/linux/bitops.h | diffblobblamehistory |