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Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods
Date 2017-07-12 10:40 +0200
Message-ID <u2llF-5Pi-19@gated-at.bofh.it> (permalink)
References (5 earlier) <u1Vhv-65c-3@gated-at.bofh.it> <u1ZXR-zq-23@gated-at.bofh.it> <u25TA-4wz-3@gated-at.bofh.it> <u26mC-4Hp-23@gated-at.bofh.it> <u2hi2-3cV-5@gated-at.bofh.it>
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On Wed, Jul 12, 2017 at 12:15:08PM +0800, Li, Aubrey wrote:
> Okay, the difference is that Mike's patch uses a very simple algorithm to make the decision.

No, the difference is that we don't end up with duplication of a metric
ton of code.

It uses the normal idle path, it just makes the NOHZ enter fail.

The condition Mike uses is why that patch never really went anywhere and
needs work.


For the condition I tend to prefer something auto-adjusting vs a tunable
threshold that everybody + dog needs to manually adjust.

So add something that measures the cost of tick_nohz_idle_{enter,exit}()
and base the threshold off of that. Then of course, there's the question
which of the idle estimates to use.

The cpuidle idle estimate includes IRQs, which is important for actual
idle states, but not all interrupts re-enable the tick.

The scheduler idle estimate only considers task activity, which tends to
re-enable the tick.

So the cpuidle estimate is pessimistic in that it'll vastly under
estimate the actual nohz period, while the scheduler estimate will over
estimate. I suspsect the scheduler one is closer to the actual nohz
duration, but this is something we'll have to play with.

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Thread

[RFC PATCH v1 00/11] Create fast idle path for short idle periods Aubrey Li <aubrey.li@intel.com> - 2017-07-10 03:50 +0200
  [RFC PATCH v1 04/11] sched/idle: make the fast idle path for short idle periods Aubrey Li <aubrey.li@intel.com> - 2017-07-10 03:50 +0200
    Re: [RFC PATCH v1 04/11] sched/idle: make the fast idle path for  short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-11 15:00 +0200
      Re: [RFC PATCH v1 04/11] sched/idle: make the fast idle path for  short idle periods Frederic Weisbecker <fweisbec@gmail.com> - 2017-07-11 18:40 +0200
        Re: [RFC PATCH v1 04/11] sched/idle: make the fast idle path for  short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-11 20:20 +0200
          Re: [RFC PATCH v1 04/11] sched/idle: make the fast idle path for  short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-12 05:30 +0200
            Re: [RFC PATCH v1 04/11] sched/idle: make the fast idle path for  short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-12 07:10 +0200
              Re: [RFC PATCH v1 04/11] sched/idle: make the fast idle path for  short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-12 07:30 +0200
        Re: [RFC PATCH v1 04/11] sched/idle: make the fast idle path for  short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-12 14:30 +0200
  [RFC PATCH v1 05/11] cpuidle: update idle statistics before cpuidle governor Aubrey Li <aubrey.li@intel.com> - 2017-07-10 03:50 +0200
  [RFC PATCH v1 08/11] cpuidle: menu: remove reduplicative implementation Aubrey Li <aubrey.li@intel.com> - 2017-07-10 04:00 +0200
  [RFC PATCH v1 07/11] cpuidle: make idle residency update more generic Aubrey Li <aubrey.li@intel.com> - 2017-07-10 04:00 +0200
  [RFC PATCH v1 03/11] cpuidle: introduce cpuidle governor for idle prediction Aubrey Li <aubrey.li@intel.com> - 2017-07-10 04:00 +0200
    Re: [RFC PATCH v1 03/11] cpuidle: introduce cpuidle governor for  idle prediction Peter Zijlstra <peterz@infradead.org> - 2017-07-12 14:20 +0200
  [RFC PATCH v1 09/11] cpuidle: menu: feed cpuidle prediction to menu governor Aubrey Li <aubrey.li@intel.com> - 2017-07-10 04:00 +0200
  Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-10 10:50 +0200
    Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Wanpeng Li <kernellwp@gmail.com> - 2017-07-10 11:40 +0200
    Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-10 16:00 +0200
    Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Andi Kleen <ak@linux.intel.com> - 2017-07-10 16:50 +0200
      Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-10 18:50 +0200
        Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Andi Kleen <ak@linux.intel.com> - 2017-07-10 19:30 +0200
          Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-11 06:50 +0200
            Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-11 11:50 +0200
              Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Frederic Weisbecker <fweisbec@gmail.com> - 2017-07-11 18:10 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-11 18:40 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-11 20:10 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-12 14:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-12 18:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-12 19:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-12 21:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-12 21:10 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-12 14:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-12 18:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-12 19:20 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-12 20:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-12 21:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-12 20:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-13 10:40 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-12 06:20 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-12 10:40 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Andi Kleen <ak@linux.intel.com> - 2017-07-12 23:40 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-13 10:40 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-13 16:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-13 17:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-13 17:20 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-13 20:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-14 06:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-14 17:40 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-14 18:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Andi Kleen <ak@linux.intel.com> - 2017-07-14 18:10 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-17 11:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-17 15:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Andi Kleen <ak@linux.intel.com> - 2017-07-14 18:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-14 18:10 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Andi Kleen <ak@linux.intel.com> - 2017-07-14 18:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-17 21:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Arjan van de Ven <arjan@linux.intel.com> - 2017-07-17 21:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle  periods Thomas Gleixner <tglx@linutronix.de> - 2017-07-17 21:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Arjan van de Ven <arjan@linux.intel.com> - 2017-07-17 22:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle  periods Thomas Gleixner <tglx@linutronix.de> - 2017-07-17 22:10 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Arjan van de Ven <arjan@linux.intel.com> - 2017-07-17 21:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle  periods Thomas Gleixner <tglx@linutronix.de> - 2017-07-17 22:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Arjan van de Ven <arjan@linux.intel.com> - 2017-07-17 22:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-18 05:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-18 05:20 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Andi Kleen <ak@linux.intel.com> - 2017-07-18 06:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle  periods Thomas Gleixner <tglx@linutronix.de> - 2017-07-18 08:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Andi Kleen <ak@linux.intel.com> - 2017-07-18 09:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle  periods Thomas Gleixner <tglx@linutronix.de> - 2017-07-18 09:20 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle  periods Thomas Gleixner <tglx@linutronix.de> - 2017-07-18 09:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-18 09:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Arjan van de Ven <arjan@linux.intel.com> - 2017-07-14 18:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-13 17:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-14 05:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-14 06:10 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-17 15:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-17 16:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-17 16:10 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-12 14:20 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle  periods Christoph Lameter <cl@linux.com> - 2017-07-11 20:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-12 04:10 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-12 04:40 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-12 20:20 +0200
          Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-11 11:10 +0200

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