RE: [PATCH] cpufreq: schedutil: Don't skip freq update when limits change

Doug Smythies
2019-07-31T23:19:19Z

On 2019.07.31 Viresh Kumar wrote:
> To avoid reducing the frequency of a CPU prematurely, we skip reducing
> the frequency if the CPU had been busy recently.
>
> This should not be done when the limits of the policy are changed, for
> example due to thermal throttling. We should always get the frequency
> within the new limits as soon as possible.
>
> Fixes: ecd288429126 ("cpufreq: schedutil: Don't set next_freq to UINT_MAX")
> Cc: v4.18+ <stable@vger.kernel.org> # v4.18+
> Reported-by: Doug Smythies <doug.smythies@gmail.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> @Doug: Can you please provide your Tested-by for this commit, as it
> already fixed the issue around acpi-cpufreq driver.
>
> We will continue to see what's wrong with intel-pstate though.

Please give me a few more hours.
I'll reply to another thread with new information at that time.

My recommendation will be to scrap this "patch2" and go back
to "patch1" [1], with a couple of modifications. The logic
of patch1 is sound.
Teaser: it is working for intel_cpufreq/schedutil, but I
have yet to test acpi-cpufreq/schedutil.

[1] https://marc.info/?l=linux-pm&m=156377832225470&w=2

... Doug