From: Waiman Long <waiman.long@hp.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
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>
Subject: Re: [PATCH v5 1/6] locking/pvqspinlock: Unconditional PV kick with _Q_SLOW_VAL
Date: Thu, 13 Aug 2015 22:07:16 -0400 [thread overview]
Message-ID: <55CD4D54.2090008@hp.com> (raw)
In-Reply-To: <20150808060249.GT16853@twins.programming.kicks-ass.net>
On 08/08/2015 02:02 AM, Peter Zijlstra wrote:
> On Fri, Aug 07, 2015 at 11:17:56PM -0400, Waiman Long wrote:
>> 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.
> This is half the patch it should be.
>
> Because if the load is not needed, then the store is not either, and
> then there's the comments to update.
Sorry for the late reply.
That is true. Setting state to vcpu_hashed in pv_wait_head() isn't
really necessary. I kept it there for consistency sake as the state may
be set to vcpu_hashed in pv_kick_node(). We can certainly take that out.
BTW, could you also review the other patches when you have time? I am
coming to the LinuxCon/Plumbers next week. Hopefully, I can chat with
you again.
Cheers,
Longman
next prev parent reply other threads:[~2015-08-14 2:07 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 ` [PATCH v5 1/6] locking/pvqspinlock: Unconditional PV kick with _Q_SLOW_VAL Waiman Long
2015-08-08 6:02 ` Peter Zijlstra
2015-08-14 2:07 ` Waiman Long [this message]
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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