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Message-Id: <20210127203627.47510-3-alexander.sverdlin@nokia.com>
Date: Wed, 27 Jan 2021 21:36:23 +0100
From: Alexander A Sverdlin <alexander.sverdlin@...ia.com>
To: Paul Burton <paul.burton@...tec.com>, linux-mips@...r.kernel.org
Cc: Alexander Sverdlin <alexander.sverdlin@...ia.com>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Will Deacon <will@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Boqun Feng <boqun.feng@...il.com>,
Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 2/6] MIPS: Implement atomic_cmpxchg_relaxed()
From: Alexander Sverdlin <alexander.sverdlin@...ia.com>
This will save one SYNCW on Octeon and improve tight
uncontended spinlock loop performance by 17%.
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@...ia.com>
---
arch/mips/include/asm/atomic.h | 3 +++
arch/mips/include/asm/cmpxchg.h | 2 ++
2 files changed, 5 insertions(+)
diff --git a/arch/mips/include/asm/atomic.h b/arch/mips/include/asm/atomic.h
index f904084..a4e5116 100644
--- a/arch/mips/include/asm/atomic.h
+++ b/arch/mips/include/asm/atomic.h
@@ -264,4 +264,7 @@ ATOMIC_SIP_OP(atomic64, s64, dsubu, lld, scd)
#undef ATOMIC_SIP_OP
+#define atomic_cmpxchg_relaxed(v, o, n) \
+ (cmpxchg_relaxed(&((v)->counter), (o), (n)))
+
#endif /* _ASM_ATOMIC_H */
diff --git a/arch/mips/include/asm/cmpxchg.h b/arch/mips/include/asm/cmpxchg.h
index 5b0b3a6..620f01a 100644
--- a/arch/mips/include/asm/cmpxchg.h
+++ b/arch/mips/include/asm/cmpxchg.h
@@ -182,6 +182,8 @@ unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
(unsigned long)(__typeof__(*(ptr)))(new), \
sizeof(*(ptr))))
+#define cmpxchg_relaxed cmpxchg_local
+
#define cmpxchg(ptr, old, new) \
({ \
__typeof__(*(ptr)) __res; \
--
2.10.2
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