Re: [RFC v2 3/7] Improve the tracking of active utilisation

luca abeni
2016-04-05T19:35:58Z

On Tue, 5 Apr 2016 20:00:50 +0200
Peter Zijlstra <peterz@infradead.org> wrote:

> On Tue, Apr 05, 2016 at 07:56:57PM +0200, luca abeni wrote:
> > > > + if (rq != cpu_rq(cpu)) {
> > >
> > > I don't think this is right, you want:
> > >
> > > if (task_cpu(p) != cpu) {
> > >
> > > because @cpu does not need to be task_cpu().
> > Uhm... I must have misunderstood something in the code, then :(
> > What I want to do here is to check if select_task_rq_dl() selected
> > a new CPU for this task... Since at the beginning of the function
> > rq is set as
> > rq = cpu_rq(cpu);
> > I was thinkint about checking if this is still true (if not, it
> > means that the value of "cpu" changed).
> >
> > I'll look at it again.
>
> Basically because:
>
> ac66f5477239 ("sched/numa: Introduce migrate_swap()")

Thanks; I am going to look at it

Thanks,
Luca

>
> we cannot (in general) assume .cpu == task_cpu(p).
>
> Now it might still be true for deadline tasks, but I find it easier to
> simply not rely on such assumptions.