Re: [Xen-devel] [PATCH 23/24] xen: credit2: optimize runq_tickle() a little bit

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

On Fri, 2016-09-02 at 13:38 +0100, anshul makkar wrote:
> On 17/08/16 18:20, Dario Faggioli wrote:
> > 
> > diff --git a/xen/common/sched_credit2.c
> > b/xen/common/sched_credit2.c
> > 
> > @@ -1102,13 +1110,26 @@ runq_tickle(const struct scheduler *ops, 
> >           for_each_cpu(i, &mask)
> >           {
> > -            /* Already looked at this one above */
> > -            if ( i == cpu )
> > +            /*
> > +             * Already looked at these ones above, either because
> > it's the
> > +             * cpu where new was running before, or because we are
> > at the
> > +             * hard-affinity step, and we checked this during the
> > +             * soft-affinity one
> > +             */
> Sorry for my naiveness here,
>
NP.

>  but can we be sure that situation has not 
> changed since we checked during soft-affinity step. ?
>
Yes we can, since we're holding the runqueue lock.

Regards,
Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)

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