Re: [Xen-devel] Re: VM hung after running sometime

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

 On 09/28/2010 11:01 PM, MaoXiaoyun wrote:
> Well， I just go throught the source of irqbalance, it shows that it
> balances the irq through
> updating /proc/irq/$irq/smp_affinity. That, in my understanding, set
> irq affinity is almost
> equal to irq migration.

Correct.

>
> I later find the NIC interrupt is not modified in dom0, so it is safe
> to set its affinity,
> but interrupt of xen event use handle_level_irq, set its affinity will
> subject to irq
> lost.
>
> Am I right?

I can't parse that sentence so I'm not sure. But if you have
successfully migrated the interrupt/evtchn to a different vcpu, then
there's no subsequent risk of lost events. The event loss can only
happen in the circumstance I mentioned earlier: when you migrate while
an event is being handled, and a second event occurs on the new cpu
before the first one has finished. So you need both bad timing and a
fairly high event delivery rate to trigger the problem.

J


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