linux-kernel - Re: problem in changing from active to passive mode

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Message-ID: <alpine.DEB.2.22.394.2110281908150.9518@hadrien>
Date:   Thu, 28 Oct 2021 19:10:48 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...ia.fr>
To:     Doug Smythies <dsmythies@...us.net>
cc:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Len Brown <lenb@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: problem in changing from active to passive mode

> Now, for your graph 3, are you saying this pseudo
> code of the process is repeatable?:
>
> Power up the system, booting kernel 5.9
> switch to passive/schedutil.
> wait X minutes for system to settle
> do benchmark, result ~13 seconds
> re-boot to kernel 5.15-RC
> switch to passive/schedutil.
> wait X minutes for system to settle
> do benchmark, result ~40 seconds
> re-boot to kernel 5.9
> switch to passive/schedutil.
> wait X minutes for system to settle
> do benchmark, result ~28 seconds

In the first boot of 5.9, the des (desired?) field of the HWP_REQUEST
register is 0 and in the second boot (after booting 5.15 and entering
passive mode) it is 10.  I don't know though if this is a bug or a
feature...

julia