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Date:   Tue, 5 Mar 2019 12:44:06 +0100
From:   Peter Zijlstra <>
To:     "Rafael J. Wysocki" <>
Cc:     Quentin Perret <>,
        Linux PM <>,
        LKML <>,
        Viresh Kumar <>,
        Srinivas Pandruvada <>,
        Chen Yu <>,
        Gabriele Mazzotta <>
Subject: Re: [RFT][Update][PATCH 2/2] cpufreq: intel_pstate: Update max CPU
 frequency on global turbo changes

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.

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