Re: [Xen-devel] xen/arm: Domain not fully destroyed when using credit2

[Julien Grall <julien.grall@xxxxxxx>]

On 24/01/17 14:16, Dario Faggioli wrote:
> On Tue, 2017-01-24 at 13:49 +0000, Julien Grall wrote:
> > On 24/01/17 13:40, Dario Faggioli wrote:
> > > Ah, wow... And how --forgive my naiveness-- do you measure / check
> > > that?
> > I added a print in the interrupt path (gic_interrupt for ARM) to
> > dump
> > the interrupt number. This needs to be restrict to CPU2 and above to
> > avoid been flooded:
> >
> > if ( smp_processor_id() > 1 )
> >    printk("%s: CPU%u IRQ%u\n", __FUNCTION__, smp_processor_id(),
> > irq);
> Ok.
>
> > I also added a print in the idle loop before and after the idling
> > instruction (wfi for ARM, pm_idle for x86 I think). You can see the
> > CPU
> > to go in idle mode but never coming back.
> I see. Yes, this is very different on x86.
>
> There, we have tracing (BTW, did that made it to ARM eventually?) and
> there's TRC_PM_IDLE_ENTRY/EXIT which do pretty much the same of your
> printk-s.
There is patch on the ML for xentrace support (see [1]) but nothing has 
been upstreamed yet. Waiting for a new version from the contributor.
> And if I look at it, I do see even totally idle (from the scheduler
> point of view) pCPUs, I indeed see them going back and forth from and
> to C3.
My knowledge on x86 is limited. When does a CPU decides to leave the 
idle mode?
In the case of ARM, the wfi instruction will put the CPU in idle mode 
until an interrupt is received.
Cheers,

[1] 
https://lists.xenproject.org/archives/html/xen-devel/2016-04/msg00464.html
--
Julien Grall

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