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authorYong Zhang <yong.zhang at windriver.com>2015-01-29 12:56:18 -0600
committerAnders Roxell <anders.roxell@linaro.org>2015-06-01 12:03:35 +0200
commit0bc8e682ed2f4a0eed74eca17d079222f9063a30 (patch)
parent4b1c14d38e69a3904b2dfdd68f0d10189a9561f4 (diff)
ARM: cmpxchg: define __HAVE_ARCH_CMPXCHG for armv6 and later
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 at gmail.com> Cc: Russell King <rmk+kernel at arm.linux.org.uk> Cc: Nicolas Pitre <nico at linaro.org> Cc: Will Deacon <will.deacon at arm.com> Cc: Catalin Marinas <catalin.marinas at arm.com> Cc: Thomas Gleixner <tglx at linutronix.de> Cc: linux-arm-kernel at lists.infradead.org Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h
index df2fbba7efc8..30b1a4010b89 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);