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| author | Akinobu Mita <akinobu.mita@gmail.com> | 2009-12-21 16:20:16 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-12-28 10:41:39 +0100 |
| commit | 39d997b514e12d5aff0dca206eb8996b3957927e (patch) | |
| tree | d63202847a8a421fbd1fc39e9a2433dbc86ce104 /lib/Makefile | |
| parent | 6b7b284958d47b77d06745b36bc7f36dab769d9b (diff) | |
x86, core: Optimize hweight32()
Optimize hweight32 by using the same technique in hweight64.
The proof of this technique can be found in the commit log for
f9b4192923fa6e38331e88214b1fe5fc21583fcc ("bitops: hweight()
speedup").
The userspace benchmark on x86_32 showed 20% speedup with
bitmap_weight() which uses hweight32 to count bits for each
unsigned long on 32bit architectures.
int main(void)
{
#define SZ (1024 * 1024 * 512)
static DECLARE_BITMAP(bitmap, SZ) = {
[0 ... 100] = 1,
};
return bitmap_weight(bitmap, SZ);
}
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1258603932-4590-1-git-send-email-akinobu.mita@gmail.com>
[ only x86 sets ARCH_HAS_FAST_MULTIPLIER so we do this via the x86 tree]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'lib/Makefile')
0 files changed, 0 insertions, 0 deletions