linux-kernel - Re: [PATCH 2/3] PM: EM: Make em_cpu_energy() able to return bigger values

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Date:   Wed, 7 Jul 2021 11:23:51 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org, Chris.Redpath@....com,
        dietmar.eggemann@....com, morten.rasmussen@....com,
        qperret@...gle.com, linux-pm@...r.kernel.org, rjw@...ysocki.net,
        viresh.kumar@...aro.org, vincent.guittot@...aro.org,
        mingo@...hat.com, juri.lelli@...hat.com, rostedt@...dmis.org,
        segall@...gle.com, mgorman@...e.de, bristot@...hat.com,
        CCj.Yeh@...iatek.com
Subject: Re: [PATCH 2/3] PM: EM: Make em_cpu_energy() able to return bigger
 values



On 7/7/21 11:01 AM, Peter Zijlstra wrote:
> On Wed, Jul 07, 2021 at 09:09:08AM +0100, Lukasz Luba wrote:
>> For now we would live with this simple code which improves
>> all recent 64bit platforms and is easy to take it into Android
>> common kernel. The next step would be more scattered across
>> other subsystems, so harder to backport to Android 5.4 and others.
> 
> Ah, you *do* only care about 64bit :-) So one option is to only increase
> precision for 64BIT builds, just like we do for scale_load() and
> friends.
> 

Your suggestion is potentially a good compromise :-)
We could leave the 32bit alone and they would have old code and
precision.

Thank you for the comments. Let me discuss this internally with my team.