Re: [Xen-devel] Question about the ability of credit scheduler t

To:	George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
Subject:	Re: [Xen-devel] Question about the ability of credit scheduler to handle I/O and CPU intensive VMs
From:	Yuehai Xu <yuehaixu@xxxxxxxxx>
Date:	Thu, 7 Oct 2010 20:25:12 -0400
Cc:	xen-devel@xxxxxxxxxxxxxxxxxxx, yhxu@xxxxxxxxx
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> I originally considered that when a Dom has an I/O event, its VCPU
> would be waken up, in another word, csched_vcpu_wake(struct vcpu *vc)
> should be invoked. However, I find I am definitely wrong. As long as
> there is a CPU intensive program running in a Dom, this Dom should
> never be in a state of "sleep"? In another word, it should never be
> waken up?
>

The trace result from xenalyze confirms that when a VM has a running
CPU intensive program, it never needs to be waken up. So, my question
is, how can I schedule a VM that has I/O event immediately even this
VM is CPU intensive? I think it is impossible to implement it in the
function csched_vcpu_wake.

Also, is it possible to trace the I/O procedure by xenalyze? I notice
even the macro TRC_HVM_IO_READ is defined, I don't find it is used in
anywhere.

Thanks,
Yuehai

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Re: [Xen-devel] Question about the ability of credit scheduler to handle