From: Alexander A Sverdlin <alexander.sverdlin@nokia.com>
To: Paul Burton <paul.burton@imgtec.com>, linux-mips@vger.kernel.org
Cc: Alexander Sverdlin <alexander.sverdlin@nokia.com>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Boqun Feng <boqun.feng@gmail.com>, Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH 4/6] MIPS: Octeon: qspinlock: Exclude mmiowb()
Date: Wed, 27 Jan 2021 21:36:25 +0100 [thread overview]
Message-ID: <20210127203627.47510-5-alexander.sverdlin@nokia.com> (raw)
In-Reply-To: <20210127203627.47510-1-alexander.sverdlin@nokia.com>
From: Alexander Sverdlin <alexander.sverdlin@nokia.com>
On Octeon mmiowb() is SYNCW, which is already contained in
smp_store_release(). Removing superfluous barrier brings around 10%
performance on uncontended tight spinlock loops.
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
---
arch/mips/include/asm/spinlock.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/mips/include/asm/spinlock.h b/arch/mips/include/asm/spinlock.h
index 0a707f3..fbe97b4 100644
--- a/arch/mips/include/asm/spinlock.h
+++ b/arch/mips/include/asm/spinlock.h
@@ -21,8 +21,10 @@
*/
static inline void queued_spin_unlock(struct qspinlock *lock)
{
+#ifndef CONFIG_CPU_CAVIUM_OCTEON
/* This could be optimised with ARCH_HAS_MMIOWB */
mmiowb();
+#endif
smp_store_release(&lock->locked, 0);
#ifdef CONFIG_CPU_CAVIUM_OCTEON
nudge_writes();
--
2.10.2
next prev parent reply other threads:[~2021-01-27 20:38 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-27 20:36 [PATCH 0/6] MIPS: qspinlock: Try to reduce reduce the spinlock regression Alexander A Sverdlin
2021-01-27 20:36 ` [PATCH 1/6] MIPS: Octeon: Implement __smp_store_release() Alexander A Sverdlin
2021-01-27 22:32 ` Peter Zijlstra
2021-01-28 7:27 ` Alexander Sverdlin
2021-01-28 11:33 ` Peter Zijlstra
2021-01-28 11:52 ` Alexander Sverdlin
2021-01-28 14:57 ` Peter Zijlstra
2021-01-28 15:15 ` Peter Zijlstra
2021-01-28 12:09 ` Alexander Sverdlin
2021-01-28 15:04 ` Peter Zijlstra
2021-01-27 20:36 ` [PATCH 2/6] MIPS: Implement atomic_cmpxchg_relaxed() Alexander A Sverdlin
2021-01-27 20:36 ` [PATCH 3/6] MIPS: Octeon: qspinlock: Flush write buffer Alexander A Sverdlin
2021-01-27 22:34 ` Peter Zijlstra
2021-01-28 7:29 ` Alexander Sverdlin
2021-01-28 11:35 ` Peter Zijlstra
2021-01-28 12:13 ` Alexander Sverdlin
2021-01-28 15:26 ` Peter Zijlstra
2021-01-27 20:36 ` Alexander A Sverdlin [this message]
2021-01-27 22:35 ` [PATCH 4/6] MIPS: Octeon: qspinlock: Exclude mmiowb() Peter Zijlstra
2021-01-27 20:36 ` [PATCH 5/6] MIPS: Provide {atomic_}xchg_relaxed() Alexander A Sverdlin
2021-01-27 20:36 ` [PATCH 6/6] MIPS: cmpxchg: Use cmpxchg_local() for {cmp_}xchg_small() Alexander A Sverdlin
2021-01-27 22:37 ` Peter Zijlstra
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