From mboxrd@z Thu Jan 1 00:00:00 1970 From: yong.zhang0@gmail.com (Yong Zhang) Date: Wed, 30 May 2012 15:51:26 +0800 Subject: [RFC PATCH] ARM: cmpxchg: define __HAVE_ARCH_CMPXCHG for armv6 and later Message-ID: <1338364287-11614-1-git-send-email-yong.zhang0@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Yong Zhang 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 Cc: Russell King Cc: Nicolas Pitre Cc: Will Deacon Cc: Catalin Marinas Cc: Thomas Gleixner Cc: linux-arm-kernel at lists.infradead.org --- 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