diff options
| author | Andi Kleen <ak@suse.de> | 2006-09-26 10:52:38 +0200 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2006-09-26 10:52:38 +0200 |
| commit | 0136611c62e8650e354b95c76dff6d2ce6030eff (patch) | |
| tree | 9ba66105bccc4d83b84663b8dda7e51962c22a04 /include/asm-x86_64 | |
| parent | 8380aabb99719af583447133f19a4d8074b5c337 (diff) | |
| download | op-kernel-dev-0136611c62e8650e354b95c76dff6d2ce6030eff.zip op-kernel-dev-0136611c62e8650e354b95c76dff6d2ce6030eff.tar.gz | |
[PATCH] optimize hweight64 for x86_64
Based on patch from David Rientjes <rientjes@google.com>, but
changed by AK.
Optimizes the 64-bit hamming weight for x86_64 processors assuming they
have fast multiplication. Uses five fewer bitops than the generic
hweight64. Benchmark on one EMT64 showed ~25% speedup with 2^24
consecutive calls.
Define a new ARCH_HAS_FAST_MULTIPLIER that can be set by other
architectures that can also multiply fast.
Signed-off-by: Andi Kleen <ak@suse.de>
Diffstat (limited to 'include/asm-x86_64')
| -rw-r--r-- | include/asm-x86_64/bitops.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/asm-x86_64/bitops.h b/include/asm-x86_64/bitops.h index f7ba57b..5b535ea 100644 --- a/include/asm-x86_64/bitops.h +++ b/include/asm-x86_64/bitops.h @@ -399,6 +399,8 @@ static __inline__ int fls(int x) return r+1; } +#define ARCH_HAS_FAST_MULTIPLIER 1 + #include <asm-generic/bitops/hweight.h> #endif /* __KERNEL__ */ |
