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RE: [Xen-devel] cpuidle causing Dom0 soft lockups

To: "Ke Yu" <ke.yu@xxxxxxxxx>,"Kevin Tian" <kevin.tian@xxxxxxxxx>
Subject: RE: [Xen-devel] cpuidle causing Dom0 soft lockups
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Mon, 08 Feb 2010 08:45:58 +0000
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>>> "Tian, Kevin" <kevin.tian@xxxxxxxxx> 06.02.10 02:52 >>>
>>From: Jan Beulich [mailto:JBeulich@xxxxxxxxxx] 
>>Sent: 2010年2月5日 23:52
>>
>>>>> "Jan Beulich" <JBeulich@xxxxxxxxxx> 05.02.10 15:59 >>>
>>>Next I'll do is try to detect when the duty CPU is de-scheduled, and
>>>move on the duty to one that is scheduled (i.e. one that is currently
>>>executing timer_interrupt()).
>>
>>This improves the situation (the highest spike I saw so far was 2,000
>>interrupts per CPU per second), but doesn't get it back the way it
>>ought to be (apart from the spikes, as with the original version of the
>>patch, interrupt activity is also generally too high, very erratic, and
>>even during the more quiet periods doesn't go down to the original
>>level).
>>
>
>could you send out your new patch? in same time, tweaking singleshot

Attached. After another refinement (in stop_hz_timer()) I didn't see
spikes above 1,000 interrupts per CPU per second anymore. But it's
still far from being as quiescent as without the patch.

What's also interesting is that there's an initial period (a minute or so)
where the interrupt rate is really stable (though still not as low as
previously), and only then it starts becoming erratic.

>timer stat from Xen side would be helpful as I said earlier. :-)

Didn't get to do that yet.

Jan

Attachment: xen-x86-xtime-lock.patch
Description: Text document

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