From: Davidlohr Bueso <dave@stgolabs.net>
To: Waiman Long <waiman.long@hpe.com>
Cc: Ding Tianhong <dingtianhong@huawei.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
"Paul E. McKenney" <paulmck@us.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <Will.Deacon@arm.com>, Jason Low <jason.low2@hp.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Waiman Long <Waiman.Long@hp.com>
Subject: Re: [PATCH RFC] locking/mutexes: don't spin on owner when wait list is not NULL.
Date: Fri, 22 Jan 2016 08:46:30 -0800 [thread overview]
Message-ID: <20160122164630.GA1633@linux-uzut.site> (raw)
In-Reply-To: <56A230C3.4070801@hpe.com>
On Fri, 22 Jan 2016, Waiman Long wrote:
>The patch that I sent out is just a proof of concept to make sure
>that it can fix that particular case. I do plan to refactor it if I
>decide to go ahead with an official one. Unlike the OSQ, there can be
>no more than one waiter spinner as the wakeup function is directed to
>only the first task in the wait list and the spinning won't happen
>until the task is first woken up. In the worst case scenario, there
>are only 2 spinners spinning on the lock and the owner field, one
>from OSQ and one from the wait list. That shouldn't put too much
>cacheline contention traffic to the system.
Similarly, I guess we should also wakeup the next waiter in line after
releasing the wait_lock via wake_q. This would allow the woken waiter a
slightly better chance of finding the wait_lock free when continuing to
take the mutex.
Thanks,
Davidlohr
next prev parent reply other threads:[~2016-01-22 16:46 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-21 9:29 [PATCH RFC] locking/mutexes: don't spin on owner when wait list is not NULL Ding Tianhong
2016-01-21 21:23 ` Tim Chen
2016-01-22 2:41 ` Paul E. McKenney
2016-01-22 2:48 ` Davidlohr Bueso
2016-01-22 3:13 ` Paul E. McKenney
2016-01-21 23:02 ` Waiman Long
2016-01-22 6:09 ` Davidlohr Bueso
2016-01-22 13:38 ` Waiman Long
2016-01-22 16:46 ` Davidlohr Bueso [this message]
2016-01-25 2:23 ` [PATCH] locking/mutex: Allow next waiter lockless wakeup Davidlohr Bueso
2016-01-25 23:02 ` Waiman Long
2016-02-29 11:21 ` [tip:locking/core] " tip-bot for Davidlohr Bueso
2016-01-22 8:54 ` [PATCH RFC] locking/mutexes: don't spin on owner when wait list is not NULL Peter Zijlstra
2016-01-22 10:20 ` Jason Low
2016-01-22 10:53 ` Peter Zijlstra
2016-01-22 10:56 ` Peter Zijlstra
2016-01-22 11:06 ` Peter Zijlstra
2016-01-22 13:59 ` Waiman Long
2016-01-24 8:03 ` Ding Tianhong
2016-01-29 9:53 ` Peter Zijlstra
2016-01-30 1:18 ` Ding Tianhong
2016-02-01 3:29 ` huang ying
2016-02-01 3:35 ` Huang, Ying
2016-02-01 10:08 ` [PATCH] locking/mutex: Avoid spinner vs waiter starvation Peter Zijlstra
2016-02-02 21:19 ` Davidlohr Bueso
2016-02-03 7:10 ` Ding Tianhong
2016-02-03 19:24 ` Davidlohr Bueso
2016-02-04 1:20 ` Ding Tianhong
2016-02-12 18:33 ` Waiman Long
2016-02-03 22:07 ` Waiman Long
2016-02-04 1:35 ` Jason Low
2016-02-04 8:55 ` huang ying
2016-02-04 22:49 ` Jason Low
2016-01-22 13:41 ` [PATCH RFC] locking/mutexes: don't spin on owner when wait list is not NULL Waiman Long
-- strict thread matches above, loose matches on Subject: below --
2016-01-21 6:53 [PATCH RFC ] " Ding Tianhong
2016-01-21 7:29 ` Ingo Molnar
2016-01-21 9:04 ` Ding Tianhong
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