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Message-ID: <CAJZ5v0iMLtnab0m56PfXHo9icg-tvSjyf8yKSiTfjuChtQbvrA@mail.gmail.com>
Date: Tue, 5 Mar 2019 12:52:57 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Quentin Perret <quentin.perret@....com>,
Linux PM <linux-pm@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
Viresh Kumar <viresh.kumar@...aro.org>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
Chen Yu <yu.c.chen@...el.com>,
Gabriele Mazzotta <gabriele.mzt@...il.com>
Subject: Re: [RFT][Update][PATCH 2/2] cpufreq: intel_pstate: Update max CPU
frequency on global turbo changes
On Tue, Mar 5, 2019 at 12:44 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Tue, Mar 05, 2019 at 11:58:37AM +0100, Rafael J. Wysocki wrote:
> > So after the Peter's patch "sched/cpufreq: Fix 32bit math overflow"
> > I will need to recompute sg_cpu->min in sugov_limits().
>
> So there's still an open question; do we want that ->min thing to depend
> on available frequencies _at_all_ ?
>
> I'm thinking it might be a good thing to have the iowait boost curve be
> independent of all that.
>
> Like said; if we set it at 128 (static), it takes 9 consequtive wake-ups
> for it to reach 1024 (max). While now the curve depends on how wide the
> gap is between min_freq and max_freq. And it seems weird to have this
> behaviour depend on that. To me at least.
>
> Now, I don't know if 128/9 is the right curve, it is just a random
> number I pulled out of a hat. But it seems to make more sense than
> depending on frequencies.
I agree.
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