Re: [PATCH V5] powercap/drivers/idle_injection: Add an idle injection framework

From: Daniel Lezcano
Date: Fri Jun 08 2018 - 04:32:06 EST

On 08/06/2018 06:48, Viresh Kumar wrote:
> On 07-06-18, 16:11, Daniel Lezcano wrote:
>>>> I'm wondering if we can have a CPU hotplugged right after the
>>>> 'put_online_cpus', resulting in the 'should park' flag set and then the
>>>> thread goes in the kthread_parkme instead of jumping back the idle
>>>> injection function and decrease the count, leading up to the timer not
>>>> being set again.
>>> True. That looks like a valid problem to me as well.
>>> What about starting the hrtimer right from this routine itself, after taking
>>> into account running-time, idle-time, delay, etc ? That would get rid of the
>>> count stuff, this get_online_cpus(), etc.
>>> Even if we restart the next play-idle cycle a bit early or with some delay, sky
>>> wouldn't fall :)
>> We won't be able to call completion() in this case.
> I was just having a look at smpboot.h and saw the park/unpark callbacks. I think
> you can very much use them to align things with CPU hotplug.

Hmm, perhaps. I will have a look at it.

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