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Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency consideration

From Mike Galbraith <efault@gmx.de>
Newsgroups linux.kernel
Subject Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency consideration
Date 2017-02-22 15:50 +0100
Message-ID <tdGoV-37i-13@gated-at.bofh.it> (permalink)
References <tdEGu-1Nw-15@gated-at.bofh.it> <tdEZP-2cZ-9@gated-at.bofh.it> <tdEZP-2cZ-11@gated-at.bofh.it> <tdGfg-32X-9@gated-at.bofh.it>
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On Wed, 2017-02-22 at 22:31 +0800, Alex Shi wrote:
> 
> On 02/22/2017 09:19 PM, Mike Galbraith wrote:
> > On Wed, 2017-02-22 at 14:12 +0100, Peter Zijlstra wrote:
> > > On Wed, Feb 22, 2017 at 01:56:37PM +0100, Mike Galbraith wrote:
> > > > Hi,
> > > > 
> > > > Do we really need a spinlock for that in the idle loop?
> > > 
> > > Urgh, that's broken on RT, you cannot schedule the idle loop.
> > 
> > That's what made me notice the obnoxious little bugger.
> 
> Hi Mike,
> 
> Sorry for this bug. Guess the rt_spin_lock call some function in
> rtmutex.c:995. Could you like to show me how to reproduce this bug?

Yeah, spinlock_t is transmogrified into an rtmutex in RT trees.  No
need to reproduce, if you just make the lock go away, RT trees will
become happy camper again, and NONRT trees won't have to feed yet
another an cycle sucking lock in the fastpath.

	-Mike

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Thread

9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Mike Galbraith <efault@gmx.de> - 2017-02-22 14:00 +0100
  Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Peter Zijlstra <peterz@infradead.org> - 2017-02-22 14:20 +0100
    Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Mike Galbraith <efault@gmx.de> - 2017-02-22 14:20 +0100
      Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Peter Zijlstra <peterz@infradead.org> - 2017-02-22 15:40 +0100
        Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Alex Shi <alex.shi@linaro.org> - 2017-02-22 16:00 +0100
          Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency consideration "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-02-23 13:30 +0100
            Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Mike Galbraith <efault@gmx.de> - 2017-02-23 14:20 +0100
              Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Alex Shi <alex.shi@linaro.org> - 2017-02-23 15:10 +0100
            Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Alex Shi <alex.shi@linaro.org> - 2017-02-23 15:10 +0100
              Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency consideration "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-02-23 23:40 +0100
                Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Alex Shi <alex.shi@linaro.org> - 2017-02-24 03:00 +0100
                [PATCH] cpuidle: menu: Avoid taking spinlock for accessing QoS values "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-02-24 13:40 +0100
      Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Alex Shi <alex.shi@linaro.org> - 2017-02-22 15:40 +0100
        Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Mike Galbraith <efault@gmx.de> - 2017-02-22 15:50 +0100
    Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Alex Shi <alex.shi@linaro.org> - 2017-02-22 16:00 +0100
      Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Mike Galbraith <efault@gmx.de> - 2017-02-22 16:10 +0100
        Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Alex Shi <alex.shi@linaro.org> - 2017-02-22 16:40 +0100
          Re: 9908859acaa9 cpuidle/menu: add per CPU PM QoS resume latency  consideration Mike Galbraith <efault@gmx.de> - 2017-02-22 16:50 +0100

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