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

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

Hi, Keir,
        Please check whether attached patch matches 
your suggestion. Test OK with vcpu hotplug and save/restore.

Thanks,
Kevin
 
>From: Tian, Kevin
>Sent: 2007年2月2日 10:49
>>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

Attachment: softlockup_fix.patch
Description: softlockup_fix.patch

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