Re: [PATCH] Revert "cpufreq: schedutil: Don't restrict kthread to related_cpus unnecessarily"

[Rafael J. Wysocki]

On Tue, May 8, 2018 at 12:34 PM, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
> On 08-05-18, 11:02, Quentin Perret wrote:
>> The sugov kthreads are DL tasks so they're not impacted by EAS. But even
>> if you take EAS out of the picture, those kthreads are assigned to a
>> "random" CPU at boot time and stay there forever (because that's how DL
>> works). Is this what we want ?
>
> Okay, I didn't knew that DL threads don't migrate at all. I don't
> think that's what we want then specially for big LITTLE platforms. But
> for the rest, I don't know. Take example of Qcom krait. Each CPU has a
> separate policy, why shouldn't we allow other CPUs to run the kthread?

Because that makes things more complex and harder to debug in general.

What's the exact reason why non-policy CPUs should ever run the sugov
kthread for the given policy?