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powerpc: Use CONFIG_ARCH_HAS_FAST_MULTIPLIER

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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>
This commit is contained in:
Anton Blanchard 2014-09-16 10:49:14 +10:00 committed by Michael Ellerman
parent ff2e466aa2
commit 423216ed32
1 changed files with 2 additions and 0 deletions
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arch/powerpc/platforms/Kconfig.cputype
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@ -116,10 +116,12 @@ config POWER6_CPU
config POWER7_CPU
bool "POWER7"
depends on PPC_BOOK3S_64
select ARCH_HAS_FAST_MULTIPLIER
config POWER8_CPU
bool "POWER8"
depends on PPC_BOOK3S_64
select ARCH_HAS_FAST_MULTIPLIER
config E5500_CPU
bool "Freescale e5500"