linux-kernel - Re: [RFC/RFT][PATCH 1/2] cpufreq: schedutil: Use policy-dependent transition delays

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Date:   Tue, 11 Apr 2017 16:01:42 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>,
        Juri Lelli <juri.lelli@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Joel Fernandes <joelaf@...gle.com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Brendan Jackman <brendan.jackman@....com>
Subject: Re: [RFC/RFT][PATCH 1/2] cpufreq: schedutil: Use policy-dependent
 transition delays

On Tue, Apr 11, 2017 at 1:14 PM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> On 11-04-17, 00:20, Rafael J. Wysocki wrote:
>> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>>
>> Make the schedutil governor take the initial (default) value of the
>> rate_limit_us sysfs attribute from the (new) transition_delay_us
>> policy parameter (to be set by the scaling driver).
>>
>> That will allow scaling drivers to make schedutil use smaller default
>> values of rate_limit_us and reduce the default average time interval
>> between consecutive frequency changes.
>>
>> Make intel_pstate set transition_delay_us to 500.
>>
>> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>> ---
>>
>> This is a replacement for https://patchwork.kernel.org/patch/9671831/
>>
>> ---
>>  drivers/cpufreq/intel_pstate.c   |    2 ++
>>  include/linux/cpufreq.h          |    7 +++++++
>>  kernel/sched/cpufreq_schedutil.c |   15 ++++++++++-----
>>  3 files changed, 19 insertions(+), 5 deletions(-)
>
> Should we use this new value for the ondemand/conservative governors as well?

We might, but it is mostly for schedutil.

Thanks,
Rafael