Hi Dario,
Thank you very much for the explanation! I got it. To be specific,
2015-11-04 10:52 GMT-05:00 Dario Faggioli <dario.faggi...@citrix.com>:
> On Wed, 2015-11-04 at 10:01 -0500, Meng Xu wrote:
> > 2015-11-04 9:12 GMT-05:00 Dario Faggioli <dario.faggi...@citrix.com>:
> > > Just FTR (and for next time :-D), is the above something that can
> > > be
> > > interpreted as a 'Reviewed-by: Meng Xu <xxx>' ? If no (e.g.,
> > > because
> > > you haven't looking thoroughly enough to feel confident to express
> > > it),
> > > then fine, I was just asking.
> > Thank you very much for explaining this for me. :-)
> >
> > I feel confident about the changes for RTDS scheduler.
> >
> Ok.
>
> > I'm not so confident about the change in the schedule.c. To be
> > specific, this patch removes insert_vcpu in schedule_cpu_switch() in
> > schedule.c;
> >
> It removes the attempt of inserting the idle vCPU in the runqueue of
> the scheduler of the target cpupool for the pCPU.
>
> More specifically, this line:
>
> SCHED_OP(new_ops, insert_vcpu, idle);
>
I neglected the parameter "idle" here. :-)
> If we look at the various ways in which insert_vcpu is implemented, we
> have:
>
> csched_vcpu_insert:
>
> if ( !__vcpu_on_runq(svc) && vcpu_runnable(vc) && !vc->is_running )
> __runq_insert(vc->processor, svc);
>
> but the pCPU being switched is free, i.e., it is not in any cpupool,
> and it is idling. So, the idle vCPU is running, and the condition above
> is false, which means __runq_insert() is not really called.
>
> csched2_vcpu_insert:
>
> if ( ! is_idle_vcpu(vc) )
> {
> ...
> }
>
> so trying to insert the idle vCPU is actually a nop.
>
> rt_vcpu_insert:
>
> if ( is_idle_vcpu(vc) )
> return;
>
>
> a nop again.
>
>
Yes. :-) After seeing this, I recalled... :-D
> My point being that this patch actually removes nothing but a bunch of
> if()-s, with no effect at all.
>
> > I'm not so sure if it is ok to insert_vcpu when a domain is moved.
>
> >
> Hopefully, I addressed your doubts.
>
Yes. It clears my doubts. :-D
> Ok, I haven't sent v4 yet, so I'll apply it there. Thanks.
>
>
Thank you very much for your explanation!
Now I'm confident about
Reviewed-by: Meng Xu <men...@cis.upenn.edu>
I saw the v4 patch series that comes with the Reviewed-by above. So I think
you don't need to do anything.
Best regards,
Meng
-----------
Meng Xu
PhD Student in Computer and Information Science
University of Pennsylvania
http://www.cis.upenn.edu/~mengxu/
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
