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

From Arjan van de Ven <arjan@linux.intel.com>
Newsgroups linux.kernel
Subject Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods
Date 2017-07-18 17:30 +0200
Message-ID <u4CBH-45e-13@gated-at.bofh.it> (permalink)
References (6 earlier) <u4rdf-5rV-1@gated-at.bofh.it> <u4sCl-6f0-3@gated-at.bofh.it> <u4uut-7ol-11@gated-at.bofh.it> <u4uEa-7rF-15@gated-at.bofh.it> <u4CBH-45e-9@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 7/18/2017 8:20 AM, Paul E. McKenney wrote:
> 3.2) how to determine if the idle is short or long. My current proposal is to
> use a tunable value via /sys, while Peter prefers an auto-adjust mechanism. I
> didn't get the details of an auto-adjust mechanism yet


the most obvious way to do this (for me, maybe I'm naive) is to add another
C state, lets call it "C1-lite" with its own thresholds and power levels etc,
and just let that be picked naturally based on the heuristics.
(if we want to improve the heuristics, that's fine and always welcome but that
is completely orthogonal in my mind)

this C1-lite would then skip some of the idle steps like the nohz logic. How we
plumb that ... might end up being a flag or whatever, we'll figure that out easily.

as long as "real C1" has a break even time that is appropriate compared to C1-lite,
we'll only pick C1-lite for very very short idles like is desired...
but we don't end up creating a parallel infra for picking states, that part just does
not make sense to me tbh.... I have yet to see any reason why C1-lite couldn't be just
another C-state for everything except the actual place where we do the "go idle" last
bit of logic.

(Also note that for extreme short idles, today we just spinloop (C0), so by this argument
we should also do a C0-lite.. or make this C0 always the lite variant)

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[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 Frederic Weisbecker <fweisbec@gmail.com> - 2017-07-19 15:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-19 17:00 +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 Peter Zijlstra <peterz@infradead.org> - 2017-07-18 21:00 +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 05:20 +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 "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-19 08:20 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle  periods Thomas Gleixner <tglx@linutronix.de> - 2017-07-19 10:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-20 04:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle  periods Thomas Gleixner <tglx@linutronix.de> - 2017-07-20 10:20 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Arjan van de Ven <arjan@linux.intel.com> - 2017-07-20 15:50 +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 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-18 17:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Arjan van de Ven <arjan@linux.intel.com> - 2017-07-18 17:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Arjan van de Ven <arjan@linux.intel.com> - 2017-07-18 18:40 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-18 19:10 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-18 18:40 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-19 07:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-19 16:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle  periods Christopher Lameter <cl@linux.com> - 2017-07-19 17:10 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-19 19:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Li, Aubrey" <aubrey.li@linux.intel.com> - 2017-07-20 03:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-20 15:00 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Arjan van de Ven <arjan@linux.intel.com> - 2017-07-20 15:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-20 16:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-07-20 18:10 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-18 18:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-18 15:30 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Peter Zijlstra <peterz@infradead.org> - 2017-07-19 15:50 +0200
                Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Arjan van de Ven <arjan@linux.intel.com> - 2017-07-14 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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