linux-kernel - Re: [PATCH v2 12/17] PM: EM: Add argument to get

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Message-ID: <93afb0fd-6226-4b0d-380a-182ecf028b34@arm.com>
Date:   Tue, 30 May 2023 11:53:53 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Lukasz Luba <lukasz.luba@....com>, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, rafael@...nel.org
Cc:     rui.zhang@...el.com, amit.kucheria@...durent.com,
        amit.kachhap@...il.com, daniel.lezcano@...aro.org,
        viresh.kumar@...aro.org, len.brown@...el.com, pavel@....cz,
        Pierre.Gondois@....com, ionela.voinescu@....com,
        rostedt@...dmis.org, mhiramat@...nel.org
Subject: Re: [PATCH v2 12/17] PM: EM: Add argument to get_cost() for runtime
 modification

On 12/05/2023 11:57, Lukasz Luba wrote:
> The Energy Model (EM) supports runtime modifications. Let also the
> artificial EM use this new feature and allow to update the 'cost' values
> at runtime. When the artificial EM is used there is a need to provide
> two callbacks: get_cost() and update_power(), not only the last one.
> 
> Update also CPPC driver code, since the new argument is needed there
> to compile properly and register EM.

Is there a real use case behind this? It can't be mobile which IMHO
drivers the rest of the 'Runtime modifiable EM' feature.

Do we know of any machine using the artificial EM. And do they care
about EM matching workload or static power?

[...]