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Re: [Xen-devel] Re: [PATCH 1/4] CPU online/offline support in Xen

To: "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>, Christoph Egger <Christoph.Egger@xxxxxxx>
Subject: Re: [Xen-devel] Re: [PATCH 1/4] CPU online/offline support in Xen
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Thu, 18 Sep 2008 10:11:28 +0100
Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Shan, Haitao" <haitao.shan@xxxxxxxxx>, Gavin Maltby <Gavin.Maltby@xxxxxxx>, Haitao Shan <maillists.shan@xxxxxxxxx>
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Thread-topic: [Xen-devel] Re: [PATCH 1/4] CPU online/offline support in Xen
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On 18/9/08 09:13, "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx> wrote:

>>> Hmm, I think current NMI_MCE_SOFTIRQ can't make sure other
>> guest will not be
>>> scheduled. Considering there is a schedule softirq already
>> pending on the
>>> pCPU, other guest may run before the impacted guest. Did I
>> missed anything?
>> There are races here in any case. What if #MC happens halfway
>> through the
>> scheduler, just before set_current(new)?
> If MCE handler will not cause schedule and not change current, will any issue
> happen?

I'm not sure exactly what you mean. What *I* meant was that there are
certain points during execution where, if a #MC occurs, it may not be
possible to determine which single vCPU was running on the pCPU. I guess
though that if you ever get unrecoverable errors reported while running
inside the hypervisor, you probably can't recover anyway.

 -- Keir

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