Re: [Xen-devel] state of process on de-scheduled vCPU

[David Xu <davidxu06@xxxxxxxxx>]

Hi George,

Thanks for your quick reply. In my question, the running state is mainly for the process. For example, when a vCPU becomes OVER, what's the state of the running process(this process in running when this vCPU is UNDER) on it? Besides, do you mean that from the guest's perspective its time is frozen when the corresponding vCPU is de-scheduled? In this case, how about vSMP? If a VM has 2 vCPUs, one is de-scheduled and the other is running, the time on the running vCPU will continue going ahead, right? Thanks.

Regards,

Cong

2012/11/12 George Dunlap <George.Dunlap@xxxxxxxxxxxxx>

On Sun, Nov 11, 2012 at 3:57 AM, David Xu <davidxu06@xxxxxxxxx> wrote:

Hi all,

I wonder if the state of process in guestOS will change when the corresponding vCPU is de-scheduled. In other words, when a vCPU uses up its credits and its state become over, how about the process context or softirq context in guest OS on this vCPU? Does it still maintain the same running state? Thanks.

I'm not sure what you mean "the same running state".  The state of the vcpu -- the registers, the guest memory relating to it, and the fact that it's not blocked -- is the same.  From the guest's perspective, it has temporarily frozen in time until it gets to run again.  Does that answer your question?

 -George

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