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From: Jason Low <jason.low2@hpe.com>
To: imre.deak@intel.com
Cc: jason.low2@hpe.com, Peter Zijlstra <peterz@infradead.org>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	Chris Wilson <chris@chris-wilson.co.uk>,
	Daniel Vetter <daniel.vetter@intel.com>,
	Waiman Long <Waiman.Long@hpe.com>,
	Davidlohr Bueso <dave@stgolabs.net>
Subject: Re: [RFC] Avoid mutex starvation when optimistic spinning is disabled
Date: Thu, 21 Jul 2016 13:57:38 -0700	[thread overview]
Message-ID: <1469134658.2344.12.camel@j-VirtualBox> (raw)
In-Reply-To: <1469021399.19093.14.camel@intel.com>

On Wed, 2016-07-20 at 16:29 +0300, Imre Deak wrote:
> On ti, 2016-07-19 at 21:39 -0700, Jason Low wrote:
> > On Tue, 2016-07-19 at 16:04 -0700, Jason Low wrote:
> > > Hi Imre,
> > > 
> > > Here is a patch which prevents a thread from spending too much "time"
> > > waiting for a mutex in the !CONFIG_MUTEX_SPIN_ON_OWNER case.
> > > 
> > > Would you like to try this out and see if this addresses the mutex
> > > starvation issue you are seeing in your workload when optimistic
> > > spinning is disabled?
> > 
> > Although it looks like it didn't take care of the 'lock stealing' case
> > in the slowpath. Here is the updated fixed version:
> 
> This also got rid of the problem, I only needed to change the ww
> functions accordingly. Also, imo mutex_trylock() needs the same
> handling

Good point. I supposed mutex_trylock() may not be causing starvation
issues, but I agree that it makes sense if mutex_trylock() fails too if
threads are supposed to yield to a waiter. I'll make the update.

Thanks,
Jason

  reply	other threads:[~2016-07-21 20:58 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-18 16:16 [RFC] locking/mutex: Fix starvation of sleeping waiters Imre Deak
2016-07-18 17:15 ` Peter Zijlstra
2016-07-18 17:47   ` Jason Low
2016-07-19 16:53     ` Imre Deak
2016-07-19 22:57       ` Jason Low
2016-07-19 23:04       ` [RFC] Avoid mutex starvation when optimistic spinning is disabled Jason Low
2016-07-20  4:39         ` Jason Low
2016-07-20 13:29           ` Imre Deak
2016-07-21 20:57             ` Jason Low [this message]
2016-07-22 17:55               ` Waiman Long
2016-07-22 18:03                 ` Davidlohr Bueso
2016-07-22 18:29                   ` Imre Deak
2016-07-22 19:26                     ` Davidlohr Bueso
2016-07-22 19:53                       ` Imre Deak
2016-07-20 18:37           ` Waiman Long
2016-07-21 22:29             ` Jason Low
2016-07-22  9:34               ` Imre Deak
2016-07-22 18:44                 ` Jason Low
2016-07-22 18:01               ` Waiman Long

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