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

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx]
>Sent: 2007年2月2日 10:07
>
>Okay, I now see how this works -- the thread is kicked from
>softlockup_tick(), from the timer ISR. So this wakeup event is hidden
>from
>next_timer_interrupt(), which only searches timer wheels and hrtimers.

Exactly.

>
>The strictly correct fix here is to make next_timer_interrupt()
>softlockup-aware. I would say it is currently incorrect in the presence of
>softlockup since it is not doing its job (telling an idle process what the
>next time-based event is that it must wake up for).
>
>We can do this by adding a softlockup_get_next_event(), called from the
>bottom of next_timer_interrupt(). I would pass it the current return value
>and have it return an adjusted value: so in the absence of softlockup it
>would simply return its argument unmodified. In the presence of
>softlockup
>it would return a sooner value if softlockup is the next event to fire.
>
>Do you want to try coding this up?
>
> -- Keir

Sure.

Thanks,
Kevin

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