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Re: RFC on fixing mutex spinning on owner

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Hi Greg,

On Wed, Mar 16, 2016 at 4:35 PM, Greg Kroah-Hartman <greg@kroah.com> wrote:
> On Wed, Mar 16, 2016 at 04:22:17PM -0700, Joel Fernandes wrote:
>> Hi,
>>
>> On a fairly recent kernel and android userspace, I am seeing that with
>> i915 driver is in a spin loop waiting for mutex owner to release it
>> (mutex_spin_on_owner).
>
> Why not provide a backtrace to the drm and i915 developers so that they
> can work on this?  The mailing lists you sent this to can't do much
> about this, sorry...

I am not sure if the problem is with the i915 driver, because the
mutex spin on owner stuff is mutex related so the mutex design may
potentially need a tweak (I mentioned a proposal of adding mutex
spinning time outs).
Also since this is latency issue related (I mentioned preemptoff
tracer and preempt disabled), I sent it to linux-rt-users. Thanks for
the tip about sending it to i915 developers, incase no one here has a
say in the matter, I can drop them a note later as well.

Thanks,

Joel

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Thread

RFC on fixing mutex spinning on owner Joel Fernandes <agnel.joel@gmail.com> - 2016-03-17 00:30 +0100
  Re: RFC on fixing mutex spinning on owner Greg Kroah-Hartman <greg@kroah.com> - 2016-03-17 00:40 +0100
    Re: RFC on fixing mutex spinning on owner Joel Fernandes <agnel.joel@gmail.com> - 2016-03-17 00:40 +0100
      Re: RFC on fixing mutex spinning on owner Steven Rostedt <rostedt@goodmis.org> - 2016-03-17 03:20 +0100
        Re: RFC on fixing mutex spinning on owner Joel Fernandes <agnel.joel@gmail.com> - 2016-03-17 06:40 +0100
          Re: RFC on fixing mutex spinning on owner Steven Rostedt <rostedt@goodmis.org> - 2016-03-17 13:10 +0100
        Re: RFC on fixing mutex spinning on owner Peter Zijlstra <peterz@infradead.org> - 2016-03-17 08:40 +0100
          Re: RFC on fixing mutex spinning on owner Nicholas Mc Guire <der.herr@hofr.at> - 2016-03-17 10:10 +0100
            Re: RFC on fixing mutex spinning on owner Peter Zijlstra <peterz@infradead.org> - 2016-03-17 11:20 +0100
              Re: RFC on fixing mutex spinning on owner Thomas Gleixner <tglx@linutronix.de> - 2016-03-17 12:20 +0100
                Re: RFC on fixing mutex spinning on owner Steven Rostedt <rostedt@goodmis.org> - 2016-03-17 13:10 +0100
                Re: RFC on fixing mutex spinning on owner Peter Zijlstra <peterz@infradead.org> - 2016-03-17 13:20 +0100
                Re: RFC on fixing mutex spinning on owner Thomas Gleixner <tglx@linutronix.de> - 2016-03-17 14:40 +0100

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