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Groups > linux.kernel > #1349428
| From | Dietmar Eggemann <dietmar.eggemann@arm.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data |
| Date | 2016-03-03 18:30 +0100 |
| Message-ID | <r8Fez-21e-13@gated-at.bofh.it> (permalink) |
| References | (3 earlier) <r8je3-2XE-17@gated-at.bofh.it> <r8nKG-6bw-5@gated-at.bofh.it> <r8C71-88W-33@gated-at.bofh.it> <r8Dw7-Di-39@gated-at.bofh.it> <r8Eiv-1kl-31@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 03/03/16 16:28, Peter Zijlstra wrote:
> On Thu, Mar 03, 2016 at 04:38:17PM +0100, Peter Zijlstra wrote:
>> On Thu, Mar 03, 2016 at 03:01:15PM +0100, Vincent Guittot wrote:
>>>> In case a more formal derivation of this formula is needed, it is
>>>> based on the following 3 assumptions:
>>>>
>>>> (1) Performance is a linear function of frequency.
>>>> (2) Required performance is a linear function of the utilization ratio
>>>> x = util/max as provided by the scheduler (0 <= x <= 1).
>>>
>>> Just to mention that the utilization that you are using, varies with
>>> the frequency which add another variable in your equation
>>
>> Right, x86 hasn't implemented arch_scale_freq_capacity(), so the
>> utilization values we use are all over the map. If we lower freq, the
>> util will go up, which would result in us bumping the freq again, etc..
>
> Something like the completely untested below should maybe work.
>
> Rafael?
>
[...]
> +void arch_scale_freq_tick(void)
> +{
> + u64 aperf, mperf;
> + u64 acnt, mcnt;
> +
> + if (!static_cpu_has(X86_FEATURE_APERFMPERF))
> + return;
> +
> + aperf = rdmsrl(MSR_IA32_APERF);
> + mperf = rdmsrl(MSR_IA32_APERF);
> +
> + acnt = aperf - this_cpu_read(arch_prev_aperf);
> + mcnt = mperf - this_cpu_read(arch_prev_mperf);
> +
> + this_cpu_write(arch_prev_aperf, aperf);
> + this_cpu_write(arch_prev_mperf, mperf);
> +
> + this_cpu_write(arch_cpu_freq, div64_u64(acnt * SCHED_CAPACITY_SCALE, mcnt));
Wasn't there the problem that this ratio goes to zero if the cpu is idle
in the old power estimation approach on x86?
[...]
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[PATCH 0/6] cpufreq: schedutil governor "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-02 03:30 +0100
[PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-02 03:30 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Vincent Guittot <vincent.guittot@linaro.org> - 2016-03-02 18:20 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-02 19:00 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-02 23:50 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-03 13:30 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Juri Lelli <juri.lelli@arm.com> - 2016-03-03 13:40 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-03 17:30 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-03 17:40 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-03 17:50 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-04 02:20 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-03 18:00 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Juri Lelli <juri.lelli@arm.com> - 2016-03-03 18:20 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Juri Lelli <juri.lelli@arm.com> - 2016-03-03 18:00 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Vincent Guittot <vincent.guittot@linaro.org> - 2016-03-03 15:10 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-03 16:40 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-03 17:30 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-03 17:50 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Dietmar Eggemann <dietmar.eggemann@arm.com> - 2016-03-03 18:30 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-03 19:30 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Dietmar Eggemann <dietmar.eggemann@arm.com> - 2016-03-03 20:20 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-03 20:00 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Vincent Guittot <vincent.guittot@linaro.org> - 2016-03-03 14:10 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Steve Muckle <steve.muckle@linaro.org> - 2016-03-03 21:10 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-03 21:30 +0100
Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Steve Muckle <steve.muckle@linaro.org> - 2016-03-03 22:40 +0100
[PATCH v2 10/10] cpufreq: schedutil: New governor based on scheduler utilization data "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-04 04:40 +0100
[PATCH v2 6/10] cpufreq: Support for fast frequency switching "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-04 04:40 +0100
[PATCH v2 0/10] cpufreq: schedutil governor "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-04 04:40 +0100
[PATCH v2 1/10] cpufreq: Reduce cpufreq_update_util() overhead a bit "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-04 04:40 +0100
[PATCH v2 5/10] cpufreq: Move governor attribute set headers to cpufreq.h "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-04 04:40 +0100
Re: [PATCH v2 5/10] cpufreq: Move governor attribute set headers to cpufreq.h Viresh Kumar <viresh.kumar@linaro.org> - 2016-03-04 07:00 +0100
[PATCH v2 2/10][Resend] cpufreq: acpi-cpufreq: Make read and write operations more efficient "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-04 04:40 +0100
[PATCH v2 3/10] cpufreq: governor: New data type for management part of dbs_data "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-04 04:40 +0100
Re: [PATCH v2 3/10] cpufreq: governor: New data type for management part of dbs_data Viresh Kumar <viresh.kumar@linaro.org> - 2016-03-04 07:00 +0100
[PATCH v2 7/10] cpufreq: Rework the scheduler hooks for triggering updates "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-04 04:40 +0100
[PATCH v2 4/10] cpufreq: governor: Move abstract gov_attr_set code to seperate file "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-04 04:40 +0100
Re: [PATCH v2 4/10] cpufreq: governor: Move abstract gov_attr_set code to seperate file Viresh Kumar <viresh.kumar@linaro.org> - 2016-03-04 07:00 +0100
[PATCH v2 8/10] cpufreq: Move scheduler-related code to the sched directory "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-04 04:40 +0100
[PATCH v2 9/10] cpufreq: sched: Re-introduce cpufreq_update_util() "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-04 04:40 +0100
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