From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <Waiman.Long@hp.com>
Cc: Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
linux-doc@vger.kernel.org, Davidlohr Bueso <davidlohr@hp.com>,
Jason Low <jason.low2@hp.com>,
Scott J Norton <scott.norton@hp.com>
Subject: Re: [PATCH 1/7] locking/rwsem: don't resched at the end of optimistic spinning
Date: Mon, 4 Aug 2014 09:55:28 +0200 [thread overview]
Message-ID: <20140804075528.GI9918@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1407119782-41119-2-git-send-email-Waiman.Long@hp.com>
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On Sun, Aug 03, 2014 at 10:36:16PM -0400, Waiman Long wrote:
> For a fully preemptive kernel, a call to preempt_enable() could
> potentially trigger a task rescheduling event. In the case of rwsem
> optimistic spinning, the task has either gotten the lock or is going
> to sleep soon. So there is no point to do rescheduling here.
Uh what? Why shouldn't we preempt if we've gotten the lock? What if a
FIFO task just woke up?
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next prev parent reply other threads:[~2014-08-04 7:55 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-04 2:36 [PATCH 0/7] locking/rwsem: enable reader opt-spinning & writer respin Waiman Long
2014-08-04 2:36 ` [PATCH 1/7] locking/rwsem: don't resched at the end of optimistic spinning Waiman Long
2014-08-04 7:55 ` Peter Zijlstra [this message]
2014-08-04 18:36 ` Waiman Long
2014-08-04 20:48 ` Peter Zijlstra
2014-08-04 21:12 ` Jason Low
2014-08-05 17:54 ` Waiman Long
2014-08-04 2:36 ` [PATCH 2/7] locking/rwsem: more aggressive use " Waiman Long
2014-08-04 4:09 ` Davidlohr Bueso
2014-08-04 4:10 ` Jason Low
2014-08-04 15:44 ` Waiman Long
2014-08-13 5:51 ` Dave Chinner
2014-08-13 16:41 ` Waiman Long
2014-08-15 3:34 ` Dave Chinner
2014-08-15 17:58 ` Waiman Long
2014-08-16 7:40 ` Mike Galbraith
2014-08-17 23:41 ` Dave Chinner
2014-08-18 22:48 ` Waiman Long
2014-08-04 2:36 ` [PATCH 3/7] locking/rwsem: check for active writer/spinner before wakeup Waiman Long
2014-08-04 21:20 ` Jason Low
2014-08-05 17:56 ` Waiman Long
2014-08-04 2:36 ` [PATCH 4/7] locking/rwsem: threshold limited spinning for active readers Waiman Long
2014-08-05 4:54 ` Davidlohr Bueso
2014-08-05 5:30 ` Davidlohr Bueso
2014-08-05 5:41 ` Davidlohr Bueso
2014-08-05 18:14 ` Waiman Long
2014-08-04 2:36 ` [PATCH 5/7] locking/rwsem: move down rwsem_down_read_failed function Waiman Long
2014-08-04 2:36 ` [PATCH 6/7] locking/rwsem: enables optimistic spinning for readers Waiman Long
2014-08-04 2:36 ` [PATCH 7/7] locking/rwsem: allow waiting writers to go back to optimistic spinning Waiman Long
2014-08-04 4:25 ` [PATCH 0/7] locking/rwsem: enable reader opt-spinning & writer respin Davidlohr Bueso
2014-08-04 18:07 ` Waiman Long
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