linux-kernel - Re: [RESEND][PATCH 0/8] Introduce support for artificial Energy Model

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Date:   Mon, 4 Apr 2022 13:35:35 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     rafael@...nel.org
Cc:     dietmar.eggemann@....com, Pierre.Gondois@....com,
        ionela.voinescu@....com, viresh.kumar@...aro.org,
        daniel.lezcano@...aro.org, linux-pm@...r.kernel.org,
        mka@...omium.org, nm@...com, sboyd@...nel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, cristian.marussi@....com,
        sudeep.holla@....com, matthias.bgg@...il.com,
        linux-kernel@...r.kernel.org
Subject: Re: [RESEND][PATCH 0/8] Introduce support for artificial Energy Model

Hi Rafael,


The patch set has been on LKML for quite a while and got one ACK,
for the code touching something outside the EM (thermal cooling).

AFAICS there is no interest and objections from others for this code.

Therefore, I have a question:
What would be be process to have merge this code?
(We had internally a few reviews of this code)

On 3/21/22 09:57, Lukasz Luba wrote:
> Hi all,
> 
> This patch set adds new callback and support for artificial Energy Model (EM).
> The new EMs have artificially generated performance states.
> Such EMs can be created from lean information sources, such
> as the relative energy efficiency between CPUs. The ACPI based
> platforms provide this information
> (ACPI 6.4, s5.2.12.14 'GIC CPU Interface (GICC) Structure'
> 'Processor Power efficiency Class' field).
> 
> Artificial EMs might require to directly provide the 'cost' of
> the generated performance state. This patch set adds a new callback
> .get_cost() for this. The EM framework does not force any model
> or formula, it's up to the platform code.
> 
> Artificial EMs aim to leverage the Energy Aware Scheduler
> (EAS). Other frameworks relying on performance states
> information (i.e. IPA/DTPM) must be informed of the
> EM type and might be prevented from using it. This patch
> sets also does this by introducing a new flag:
> EM_PERF_DOMAIN_ARTIFICIAL.
> 
> The patch set is based on current linux-next, where some
> changes to OPP & EM are queuing.
> 
> The patch set also contains (patch 7/8 and patch 8/8) logic which prevents
> two EM's client frameworks from using this new EM type. Some other approach,
> using 'milli-watts', has been proposed and discussed, but refused [1].
> This new flag is more precised and should not leave space for
> wrong interpretation.
> 
> Shortly after this patch set you will see a patch set implementing the
> platform code and registering this new EM.
> 


No one from Arm is an official maintainer of the EM code.

Regards,
Lukasz