Re: [Xen-devel] [PATCH] Fix softlockup issue after vcpu hotplug

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 30/1/07 09:54, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:

> If we don't take into account blocked time, maybe we have to disable
> softlockup check. Say an idle process gets a timeout value larger than
> 10s by next_timer_interrupt, and then blocked. If, unfortunately, there's
> no other events happening before that timeout value, this vcpu will see
> softlockup warning after that timeout immediately since this period is
> not categorized into stolen time.

Presumably softlockup threads are killed and re-created when VCPUs are
offlined and onlined. Perhaps the re-creation is taking a long time? But 10s
would be a *very* long time. And once it is created and bound to the correct
VCPU we should never see long timeouts when blocking (since softlockup
thread timeout is never longer than a few seconds).

Perhaps there is a bug in our cpu onlining code -- a big timeout like that
does need investigating. I don't think we can claim this bug is root-caused
yet so it's premature to be applying patches.

 -- Keir



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