linux-kernel - Re: [PATCH 1/3] sched/fair: Prepare variables for increased precision of EAS estimated energy

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Message-ID: <ffc63114-c1c2-f866-8b2a-15e9fd0a7818@arm.com>
Date:   Wed, 30 Jun 2021 18:28:58 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Chris Redpath <Chris.Redpath@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Quentin Perret <qperret@...gle.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>, segall@...gle.com,
        Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        CCj.Yeh@...iatek.com
Subject: Re: [PATCH 1/3] sched/fair: Prepare variables for increased precision
 of EAS estimated energy



On 6/30/21 6:01 PM, Rafael J. Wysocki wrote:
> On Fri, Jun 25, 2021 at 5:26 PM Lukasz Luba <lukasz.luba@....com> wrote:
>>
>> The Energy Aware Scheduler (EAS) tries to find best CPU for a waking up
>> task. It probes many possibilities and compares the estimated energy values
>> for different scenarios. For calculating those energy values it relies on
>> Energy Model (EM) data and em_cpu_energy(). The precision which is used in
>> EM data is in milli-Watts (or abstract scale), which sometimes is not
>> sufficient. In some cases it might happen that two CPUs from different
>> Performance Domains (PDs) get the same calculated value for a given task
>> placement, but in more precised scale, they might differ. This rounding
>> error has to be addressed. This patch prepares EAS code for better
>> precision in the coming EM improvements.
>>
>> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
> 
> If you want me to pick up this series, this patch requires an ACK from
> the scheduler maintainers.
> 

It would be great, if you could take it after e.g. Peter ACK it.

Peter could you have a look at it, please?
In this patch 1/3 we have only variables upgrade.

Regards,
Lukasz