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From: Waiman Long <Waiman.Long@hp.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	Scott J Norton <scott.norton@hp.com>,
	Douglas Hatch <doug.hatch@hp.com>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Waiman Long <Waiman.Long@hp.com>
Subject: [PATCH v5 1/6] locking/pvqspinlock: Unconditional PV kick with _Q_SLOW_VAL
Date: Fri,  7 Aug 2015 23:17:56 -0400	[thread overview]
Message-ID: <1439003881-17349-2-git-send-email-Waiman.Long@hp.com> (raw)
In-Reply-To: <1439003881-17349-1-git-send-email-Waiman.Long@hp.com>

If _Q_SLOW_VAL has been set, the vCPU state must have been vcpu_hashed.
The extra check at the end of __pv_queued_spin_unlock() is unnecessary
and so is removed.

Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
---
 kernel/locking/qspinlock_paravirt.h |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
index c8e6e9a..6eafb9e 100644
--- a/kernel/locking/qspinlock_paravirt.h
+++ b/kernel/locking/qspinlock_paravirt.h
@@ -364,8 +364,7 @@ __visible void __pv_queued_spin_unlock(struct qspinlock *lock)
 	 * vCPU is harmless other than the additional latency in completing
 	 * the unlock.
 	 */
-	if (READ_ONCE(node->state) == vcpu_hashed)
-		pv_kick(node->cpu);
+	pv_kick(node->cpu);
 }
 /*
  * Include the architecture specific callee-save thunk of the
-- 
1.7.1


  reply	other threads:[~2015-08-08  3:18 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-08  3:17 [PATCH v5 0/6] locking/qspinlock: Enhance pvqspinlock performance Waiman Long
2015-08-08  3:17 ` Waiman Long [this message]
2015-08-08  6:02   ` [PATCH v5 1/6] locking/pvqspinlock: Unconditional PV kick with _Q_SLOW_VAL Peter Zijlstra
2015-08-14  2:07     ` Waiman Long
2015-08-08  3:17 ` [PATCH v5 2/6] locking/pvqspinlock: Add pending bit support Waiman Long
2015-08-08  3:17 ` [PATCH v5 3/6] locking/pvqspinlock: Collect slowpath lock statistics Waiman Long
2015-08-08  3:17 ` [PATCH v5 4/6] locking/pvqspinlock, x86: Optimize PV unlock code path Waiman Long
2015-08-08  3:18 ` [PATCH v5 5/6] locking/pvqspinlock: Allow vCPUs kick-ahead Waiman Long
2015-08-08  3:18 ` [PATCH v5 6/6] locking/pvqspinlock: Queue node adaptive spinning Waiman Long

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