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

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: RE: [Xen-devel] cpuidle causing Dom0 soft lockups
From: "Yu, Ke" <ke.yu@xxxxxxxxx>
Date: Sun, 7 Feb 2010 23:36:01 +0800
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Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] cpuidle causing Dom0 soft lockups
Jan,

The attached is the updated patch, it has two changes
- change the logic from local irq disabled *and* poll event to local irq 
disabled *or* poll event 
- Use per-CPU vcpu list to iterate the VCPU, which is more scalable. The 
original scheduler does not provide such kind of list, so this patch implement 
the list in scheduler code.

Regards
Ke

>-----Original Message-----
>From: Jan Beulich [mailto:JBeulich@xxxxxxxxxx]
>Sent: Friday, February 05, 2010 4:49 PM
>To: Yu, Ke
>Cc: Keir Fraser; Tian, Kevin; xen-devel@xxxxxxxxxxxxxxxxxxx
>Subject: RE: [Xen-devel] cpuidle causing Dom0 soft lockups
>
>Yes, this patch works for us too. So a non-hacky version of it would be
>appreciated.
>
>I also meanwhile tried out the idea to reduce the contention on
>xtime_lock (attached for reference). Things appear to work fine, but
>there is an obvious problem (with - thus far to me - no obvious
>explanation) with it: The number of timer interrupts on CPUs not on
>duty to run do_timer() and alike is increasing significantly, with spikes
>of over 100,000 per second. I'm investigating this, but of course any
>idea anyone of you might have what could be causing this would be
>very welcome.
>
>Jan
>
>>>> "Yu, Ke" <ke.yu@xxxxxxxxx> 03.02.10 08:32 >>>
>Hi Jan,
>
>Could you please try the attached patch. this patch try to avoid entering deep
>C state when there is vCPU local irq disabled, and polling event channel.
>When tested in my 64 CPU box, this issue is gone with this patch.
>
>Best Regards
>Ke

Attachment: cpuidle-hint-v3.patch
Description: cpuidle-hint-v3.patch

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