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 9:23
>
>On 2/2/07 01:10, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
>
>> So, am I looking at wrong code? In 2.6.16:
>> while (!kthread_should_stop()) {
>>                 msleep_interruptible(1000);
>>                 touch_softlockup_watchdog();
>>         }
>>
>> While in 2.6.18:
>> while (!kthread_should_stop()) {
>>                 set_current_state(TASK_INTERRUPTIBLE);
>>                 touch_softlockup_watchdog();
>>                 schedule();
>>         }
>>
>> I don't think same logic kept there. :-)
>
>Fair point! I must have compared two 2.6.16 trees...
>
>Well, that is interesting. I have no idea how
>SCHED_FIFO/sched_priority=99
>interacts with timer wheels and/or tickless idle modes. I wonder why this
>was changed at all? Perhaps a question for lkml...
>
> -- Keir

Yeah, that's the question. I can post it to lkml for an answer. But at the 
same time, do you think whether this patch is OK to be accepted into 
xen tree or not? Whatever the reason lkml may have to change that 
logic, we have to make it working correctly under xen... ;-) 

BTW, I'm not sure for generic tick-less model, but at least for 2.6.18, 
seems s390 is the only user on CONFIG_NO_IDLE_HZ which 
disables softlockup check instead.

Thanks,
Kevin

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