[PATCH v3 5/6] pv-qspinlock: use cmpxchg_release in __pv_queued_spin_unlock

From	Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Newsgroups	linux.kernel
Subject	[PATCH v3 5/6] pv-qspinlock: use cmpxchg_release in __pv_queued_spin_unlock
Date	2016-05-25 10:30 +0200
Message-ID	<rCCmt-79l-9@gated-at.bofh.it> (permalink)
References	<rCCmt-79l-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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cmpxchg_release is light-wight than cmpxchg, we can gain a better
performace then. On some arch like ppc, barrier impact the performace
too much.

Suggested-by:  Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
---
 kernel/locking/qspinlock_paravirt.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
index a5b1248..2bbffe4 100644
--- a/kernel/locking/qspinlock_paravirt.h
+++ b/kernel/locking/qspinlock_paravirt.h
@@ -614,7 +614,7 @@ __visible void __pv_queued_spin_unlock(struct qspinlock *lock)
 	 * unhash. Otherwise it would be possible to have multiple @lock
 	 * entries, which would be BAD.
 	 */
-	locked = cmpxchg(&l->locked, _Q_LOCKED_VAL, 0);
+	locked = cmpxchg_release(&l->locked, _Q_LOCKED_VAL, 0);
 	if (likely(locked == _Q_LOCKED_VAL))
 		return;
 
-- 
1.9.1

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[PATCH v3 5/6] pv-qspinlock: use cmpxchg_release in __pv_queued_spin_unlock Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-05-25 10:30 +0200
  Re: [PATCH v3 5/6] pv-qspinlock: use cmpxchg_release in  __pv_queued_spin_unlock Peter Zijlstra <peterz@infradead.org> - 2016-05-26 18:50 +0200
    Re: [PATCH v3 5/6] pv-qspinlock: use cmpxchg_release in  __pv_queued_spin_unlock Peter Zijlstra <peterz@infradead.org> - 2016-05-26 19:00 +0200
      Re: [PATCH v3 5/6] pv-qspinlock: use cmpxchg_release in __pv_queued_spin_unlock xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-05-27 12:40 +0200

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