linux-kernel - Re: [PATCH 3/3] arm64: rebuild sched domains on invariance status changes

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Date:   Fri, 25 Sep 2020 14:59:00 +0100
From:   Quentin Perret <qperret@...gle.com>
To:     Ionela Voinescu <ionela.voinescu@....com>
Cc:     mingo@...hat.com, peterz@...radead.org, vincent.guittot@...aro.org,
        catalin.marinas@....com, will@...nel.org, rjw@...ysocki.net,
        viresh.kumar@...aro.org, dietmar.eggemann@....com,
        valentin.schneider@....com, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] arm64: rebuild sched domains on invariance status
 changes

Hey Ionela,

On Thursday 24 Sep 2020 at 17:10:02 (+0100), Ionela Voinescu wrote:
> I'm not sure what is a good way of fixing this.. I could add more info
> to the warning to suggest it might be temporary ("Disabling EAS:
> frequency-invariant load tracking currently not supported"). For further
> debugging there are the additional prints guarded by sched_debug().
> 
> I'll look over the code some more to see if other ideas pop out. Any
> suggestions are appreciated.

Right, I'm not seeing anything perfect here, but I think I'd be
personally happy with this message being entirely guarded by
sched_debug(), like we do for asym CPU capacities for instance.

It's not easy to see if EAS has started at all w/o sched debug anyway,
so I expect folks who need it to enable the debug stuff during
bring-up. With a descriptive enough warn message, that should be just
fine. But that's my 2p, so I'm happy to hear if others disagree.

Thanks,
Quentin