From: Yong Zhang <yong.zhang@xxxxxxxxxxxxx> Both pi_stress and sigwaittest in rt-test show performance gain with __HAVE_ARCH_CMPXCHG. Testing result on coretile_express_a9x4: pi_stress -p 99 --duration=300 (on linux-3.4-rc5; bigger is better) vanilla: Total inversion performed: 5493381 patched: Total inversion performed: 5621746 sigwaittest -p 99 -l 100000 (on linux-3.4-rc5-rt6; less is better) 3.4-rc5-rt6: Min 24, Cur 27, Avg 30, Max 98 patched: Min 19, Cur 21, Avg 23, Max 96 Signed-off-by: Yong Zhang <yong.zhang0@xxxxxxxxx> Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> Cc: Nicolas Pitre <nico@xxxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx --- arch/arm/include/asm/cmpxchg.h | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index 7eb18c1..a91b44e 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -127,6 +127,8 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size #else /* min ARCH >= ARMv6 */ +#define __HAVE_ARCH_CMPXCHG 1 + extern void __bad_cmpxchg(volatile void *ptr, int size); /* -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
