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From: Vincent Guittot <vincent.guittot@linaro.org>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Quentin Perret <quentin.perret@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	"open list:THERMAL" <linux-pm@vger.kernel.org>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	Ingo Molnar <mingo@redhat.com>,
	Morten Rasmussen <morten.rasmussen@arm.com>,
	Chris Redpath <chris.redpath@arm.com>,
	Patrick Bellasi <patrick.bellasi@arm.com>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Thara Gopinath <thara.gopinath@linaro.org>,
	viresh kumar <viresh.kumar@linaro.org>,
	Todd Kjos <tkjos@google.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	"Cc: Steve Muckle" <smuckle@google.com>,
	adharmap@quicinc.com, "Kannan, Saravana" <skannan@quicinc.com>,
	pkondeti@codeaurora.org, Juri Lelli <juri.lelli@redhat.com>,
	Eduardo Valentin <edubezval@gmail.com>,
	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
	currojerez@riseup.net, Javi Merino <javi.merino@kernel.org>
Subject: Re: [PATCH v5 09/14] sched: Add over-utilization/tipping point indicator
Date: Mon, 6 Aug 2018 14:37:00 +0200
Message-ID: <CAKfTPtDZs2_4skbGFJkrtq1Z+G_MWue7xC3tcoLs5xcpsBkNUw@mail.gmail.com> (raw)
In-Reply-To: <1cac0d16-9f50-ed30-2460-340b077faa57@arm.com>

On Mon, 6 Aug 2018 at 14:29, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
>
> On 08/06/2018 12:33 PM, Vincent Guittot wrote:
> > On Mon, 6 Aug 2018 at 12:08, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
> >>
> >> On 08/06/2018 10:40 AM, Vincent Guittot wrote:
> >>> On Fri, 3 Aug 2018 at 17:55, Quentin Perret <quentin.perret@arm.com> wrote:
> >>>>
> >>>> On Friday 03 Aug 2018 at 15:49:24 (+0200), Vincent Guittot wrote:
> >>>>> On Fri, 3 Aug 2018 at 10:18, Quentin Perret <quentin.perret@arm.com> wrote:
> >>>>>>
> >>>>>> On Friday 03 Aug 2018 at 09:48:47 (+0200), Vincent Guittot wrote:
> >>>>>>> On Thu, 2 Aug 2018 at 18:59, Quentin Perret <quentin.perret@arm.com> wrote:
> >>
> >> [...]
> >>
> >>>> I think we're discussing two different things right now:
> >>>>       1. Should forkees go in find_energy_efficient_cpu() ?
> >>>>       2. Should forkees have 0 of initial util_avg when EAS is enabled ?
> >>>
> >>> It's the same topic: How EAS should consider a newly created task ?
> >>>
> >>> For now, we let the "performance" mode selects a CPU. This CPU will
> >>> most probably be worst CPU from a EAS pov because it's the idlest CPU
> >>> in the idlest group which is the opposite of what EAS tries to do
> >>>
> >>> The current behavior is :
> >>> For every new task, the cpu selection is done assuming it's a heavy
> >>> task with the max possible load_avg,  and it looks for the idlest cpu.
> >>> This means that if the system is lightly loaded, scheduler will select
> >>> most probably a idle big core.
> >>
> >> AFAICS, task load doesn't seem to be used for find_idlest_cpu() (
> >> find_idlest_group() and find_idlest_group_cpu()). So the forkee
> >> (SD_BALANCE_FORK) is placed independently of his task load.
> >
> > hmm ... so what is used if load or runnable load are not used ?
> > find_idlest_group() uses load and runnable load but skip spare
> > capacity in case of fork
>
> Yes, runnable load and load are used, but from the cpus, not from the task.

yes that's right, I have skipped the "task" word when reading.
So scheduler looks for the idlest CPU taking into account only CPU
loads. Then the task load starts to highest value until it get a
chance to reduce and stabilize to its final value

>
> [...]

  reply index

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-24 12:25 [PATCH v5 00/14] Energy Aware Scheduling Quentin Perret
2018-07-24 12:25 ` [PATCH v5 01/14] sched: Relocate arch_scale_cpu_capacity Quentin Perret
2018-07-24 12:25 ` [PATCH v5 02/14] sched/cpufreq: Factor out utilization to frequency mapping Quentin Perret
2018-07-24 12:25 ` [PATCH v5 03/14] PM: Introduce an Energy Model management framework Quentin Perret
2018-08-09 21:52   ` Rafael J. Wysocki
2018-08-10  8:15     ` Quentin Perret
2018-08-10  8:41       ` Rafael J. Wysocki
2018-08-10  9:12         ` Quentin Perret
2018-08-10 11:13           ` Rafael J. Wysocki
2018-08-10 12:30             ` Quentin Perret
2018-08-12  9:49               ` Rafael J. Wysocki
2018-07-24 12:25 ` [PATCH v5 04/14] PM / EM: Expose the Energy Model in sysfs Quentin Perret
2018-07-24 12:25 ` [PATCH v5 05/14] sched/topology: Reference the Energy Model of CPUs when available Quentin Perret
2018-07-24 12:25 ` [PATCH v5 06/14] sched/topology: Lowest energy aware balancing sched_domain level pointer Quentin Perret
2018-07-26 16:00   ` Valentin Schneider
2018-07-26 17:01     ` Quentin Perret
2018-07-24 12:25 ` [PATCH v5 07/14] sched/topology: Introduce sched_energy_present static key Quentin Perret
2018-07-24 12:25 ` [PATCH v5 08/14] sched/fair: Clean-up update_sg_lb_stats parameters Quentin Perret
2018-07-24 12:25 ` [PATCH v5 09/14] sched: Add over-utilization/tipping point indicator Quentin Perret
2018-08-02 12:26   ` Peter Zijlstra
2018-08-02 13:03     ` Quentin Perret
2018-08-02 13:08       ` Peter Zijlstra
2018-08-02 13:18         ` Quentin Perret
2018-08-02 13:48           ` Vincent Guittot
2018-08-02 14:14             ` Quentin Perret
2018-08-02 15:14               ` Vincent Guittot
2018-08-02 15:30                 ` Quentin Perret
2018-08-02 15:55                   ` Vincent Guittot
2018-08-02 16:00                     ` Quentin Perret
2018-08-02 16:07                       ` Vincent Guittot
2018-08-02 16:10                         ` Quentin Perret
2018-08-02 16:38                           ` Vincent Guittot
2018-08-02 16:59                             ` Quentin Perret
2018-08-03  7:48                               ` Vincent Guittot
2018-08-03  8:18                                 ` Quentin Perret
2018-08-03 13:49                                   ` Vincent Guittot
2018-08-03 14:21                                     ` Vincent Guittot
2018-08-03 15:55                                     ` Quentin Perret
2018-08-06  8:40                                       ` Vincent Guittot
2018-08-06  9:43                                         ` Quentin Perret
2018-08-06 10:45                                           ` Vincent Guittot
2018-08-06 11:02                                             ` Quentin Perret
2018-08-06 10:08                                         ` Dietmar Eggemann
2018-08-06 10:33                                           ` Vincent Guittot
2018-08-06 12:29                                             ` Dietmar Eggemann
2018-08-06 12:37                                               ` Vincent Guittot [this message]
2018-08-06 13:20                                                 ` Dietmar Eggemann
2018-08-09  9:30   ` Vincent Guittot
2018-08-09  9:38     ` Quentin Perret
2018-07-24 12:25 ` [PATCH v5 10/14] sched/cpufreq: Refactor the utilization aggregation method Quentin Perret
2018-07-30 19:35   ` skannan
2018-07-31  7:59     ` Quentin Perret
2018-07-31 19:31       ` skannan
2018-08-01  7:32         ` Rafael J. Wysocki
2018-08-01  8:23           ` Quentin Perret
2018-08-01  8:35             ` Rafael J. Wysocki
2018-08-01  9:23               ` Quentin Perret
2018-08-01  9:40                 ` Rafael J. Wysocki
2018-08-02 13:04                 ` Peter Zijlstra
2018-08-02 15:39                   ` Quentin Perret
2018-08-03 13:04                     ` Quentin Perret
2018-08-02 12:33     ` Peter Zijlstra
2018-08-02 12:45       ` Peter Zijlstra
2018-08-02 15:21         ` Quentin Perret
2018-08-02 17:36           ` Peter Zijlstra
2018-08-03 12:42             ` Quentin Perret
2018-07-24 12:25 ` [PATCH v5 11/14] sched/fair: Introduce an energy estimation helper function Quentin Perret
2018-07-24 12:25 ` [PATCH v5 12/14] sched/fair: Select an energy-efficient CPU on task wake-up Quentin Perret
2018-08-02 13:54   ` Peter Zijlstra
2018-08-02 16:21     ` Quentin Perret
2018-07-24 12:25 ` [PATCH v5 13/14] OPTIONAL: arch_topology: Start Energy Aware Scheduling Quentin Perret
2018-07-24 12:25 ` [PATCH v5 14/14] OPTIONAL: cpufreq: dt: Register an Energy Model Quentin Perret

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