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(parent: ff2e466) | patch
powerpc: Use CONFIG_ARCH_HAS_FAST_MULTIPLIER
authorAnton Blanchard <anton@samba.org>
Tue, 16 Sep 2014 00:49:14 +0000 (10:49 +1000)
committerMichael Ellerman <mpe@ellerman.id.au>
Thu, 25 Sep 2014 13:14:49 +0000 (23:14 +1000)
commit423216ed3273dae18c347ce52c5ecc193cfdd4e5
tree9f1f095dbd57904697dabd2c463e1decace2faa8tree | snapshot
parentff2e466aa2339238c941dee873e553687e941f3fcommit | diff
powerpc: Use CONFIG_ARCH_HAS_FAST_MULTIPLIER

I ran some tests to compare hash_64 using shifts and multiplies.
The results:

POWER6: ~2x slower
POWER7: ~2x faster
POWER8: ~2x faster

Now we have a proper config option, select
CONFIG_ARCH_HAS_FAST_MULTIPLIER on POWER7 and POWER8.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
arch/powerpc/platforms/Kconfig.cputype diff | blob | blame | history
Mirror https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git