Messages in this thread Patch in this message | | | From | Alexander A Sverdlin <> | Subject | [PATCH 6/6] MIPS: cmpxchg: Use cmpxchg_local() for {cmp_}xchg_small() | Date | Wed, 27 Jan 2021 21:36:27 +0100 |
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From: Alexander Sverdlin <alexander.sverdlin@nokia.com>
It makes no sense to fold smp_mb__before_llsc()/smp_llsc_mb() again and again, leave only one barrier pair in the outer function.
This removes one SYNCW from __xchg_small() and brings around 10% performance improvement in a tight spinlock loop with 6 threads on a 6 core Octeon.
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com> --- arch/mips/kernel/cmpxchg.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/mips/kernel/cmpxchg.c b/arch/mips/kernel/cmpxchg.c index 89107de..122e85f 100644 --- a/arch/mips/kernel/cmpxchg.c +++ b/arch/mips/kernel/cmpxchg.c @@ -41,7 +41,7 @@ unsigned long __xchg_small(volatile void *ptr, unsigned long val, unsigned int s do { old32 = load32; new32 = (load32 & ~mask) | (val << shift); - load32 = cmpxchg(ptr32, old32, new32); + load32 = cmpxchg_local(ptr32, old32, new32); } while (load32 != old32); return (load32 & mask) >> shift; @@ -97,7 +97,7 @@ unsigned long __cmpxchg_small(volatile void *ptr, unsigned long old, */ old32 = (load32 & ~mask) | (old << shift); new32 = (load32 & ~mask) | (new << shift); - load32 = cmpxchg(ptr32, old32, new32); + load32 = cmpxchg_local(ptr32, old32, new32); if (load32 == old32) return old; } -- 2.10.2
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