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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>
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Anton Blanchard authored and Michael Ellerman committed Sep 25, 2014
1 parent ff2e466 commit 423216e
Showing 1 changed file with 2 additions and 0 deletions.
2 changes: 2 additions & 0 deletions arch/powerpc/platforms/Kconfig.cputype
Original file line number Diff line number Diff line change
Expand Up @@ -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"
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