* [PATCH 1/2] powerpc: Add POWER8 CPU selection
@ 2014-09-16 0:47 Anton Blanchard
2014-09-16 0:49 ` [PATCH 2/2] powerpc: Use CONFIG_ARCH_HAS_FAST_MULTIPLIER Anton Blanchard
0 siblings, 1 reply; 2+ messages in thread
From: Anton Blanchard @ 2014-09-16 0:47 UTC (permalink / raw)
To: benh, paulus, michael, torvalds; +Cc: linuxppc-dev, linux-kernel
This allows the user to build a kernel targeted at POWER8
(ie gcc -mcpu=power8).
Signed-off-by: Anton Blanchard <anton@samba.org>
---
Index: b/arch/powerpc/Makefile
===================================================================
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -135,6 +135,7 @@ CFLAGS-$(CONFIG_POWER4_CPU) += $(call cc
CFLAGS-$(CONFIG_POWER5_CPU) += $(call cc-option,-mcpu=power5)
CFLAGS-$(CONFIG_POWER6_CPU) += $(call cc-option,-mcpu=power6)
CFLAGS-$(CONFIG_POWER7_CPU) += $(call cc-option,-mcpu=power7)
+CFLAGS-$(CONFIG_POWER8_CPU) += $(call cc-option,-mcpu=power8)
# Altivec option not allowed with e500mc64 in GCC.
ifeq ($(CONFIG_ALTIVEC),y)
Index: b/arch/powerpc/platforms/Kconfig.cputype
===================================================================
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -117,6 +117,10 @@ config POWER7_CPU
bool "POWER7"
depends on PPC_BOOK3S_64
+config POWER8_CPU
+ bool "POWER8"
+ depends on PPC_BOOK3S_64
+
config E5500_CPU
bool "Freescale e5500"
depends on E500
^ permalink raw reply [flat|nested] 2+ messages in thread
* [PATCH 2/2] powerpc: Use CONFIG_ARCH_HAS_FAST_MULTIPLIER
2014-09-16 0:47 [PATCH 1/2] powerpc: Add POWER8 CPU selection Anton Blanchard
@ 2014-09-16 0:49 ` Anton Blanchard
0 siblings, 0 replies; 2+ messages in thread
From: Anton Blanchard @ 2014-09-16 0:49 UTC (permalink / raw)
To: benh, paulus, michael, torvalds; +Cc: linuxppc-dev, linux-kernel
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>
---
Index: b/arch/powerpc/platforms/Kconfig.cputype
===================================================================
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -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"
^ permalink raw reply [flat|nested] 2+ messages in thread
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