[PATCH] powerpc: Remove static branch prediction in atomic{, 64}_add_unless
flat view
STALE3654d
From: Anton Blanchard <hidden>
Date: 2016-10-03 06:03:11
Subsystem:
atomic infrastructure, linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Will Deacon, Peter Zijlstra, Boqun Feng, Madhavan Srinivasan, Linus Torvalds
From: Anton Blanchard <redacted> I see quite a lot of static branch mispredictions on a simple web serving workload. The issue is in __atomic_add_unless(), called from _atomic_dec_and_lock(). There is no obvious common case, so it is better to let the hardware predict the branch. Signed-off-by: Anton Blanchard <redacted> --- arch/powerpc/include/asm/atomic.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/atomic.h b/arch/powerpc/include/asm/atomic.h
index f08d567..2b90335 100644
--- a/arch/powerpc/include/asm/atomic.h
+++ b/arch/powerpc/include/asm/atomic.h@@ -233,7 +233,7 @@ static __inline__ int __atomic_add_unless(atomic_t *v, int a, int u) PPC_ATOMIC_ENTRY_BARRIER "1: lwarx %0,0,%1 # __atomic_add_unless\n\ cmpw 0,%0,%3 \n\ - beq- 2f \n\ + beq 2f \n\ add %0,%2,%0 \n" PPC405_ERR77(0,%2) " stwcx. %0,0,%1 \n\
@@ -539,7 +539,7 @@ static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u) PPC_ATOMIC_ENTRY_BARRIER "1: ldarx %0,0,%1 # __atomic_add_unless\n\ cmpd 0,%0,%3 \n\ - beq- 2f \n\ + beq 2f \n\ add %0,%2,%0 \n" " stdcx. %0,0,%1 \n\ bne- 1b \n"
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2.7.4