Re: [Query]: tick-sched: why don't we stop tick when we are running idle task?

From: Frederic Weisbecker
Date: Tue May 13 2014 - 19:30:48 EST


On Fri, May 09, 2014 at 02:14:10PM +0530, Viresh Kumar wrote:
> On 23 April 2014 16:42, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
> > On 15 April 2014 15:00, Frederic Weisbecker <fweisbec@xxxxxxxxx> wrote:
> >> Ok, I'm a bit buzy with a conference right now but I'm going to summarize that
> >> soonish.
>
> Hi Frederic,
>
> Please see if you can find some time to close this, that would be very
> helpful :)
>
> Thanks

I'm generally worried about the accounting in update_curr() that periodically
updates stats. I have no idea which of these stats could be read by other CPUs:
vruntime, load bandwitdth, etc...

Also without tick:

* we don't poll anymore on trigger_load_balance()

* __update_cpu_load() requires fixed rate periodic polling. Alex Shi had
patches for that but I'm not sure if that's going to be merged

* rq->rt_avg accounting?
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