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

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: Tue, 12 Oct 2010 08:42:20 -0400
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, yhxu@xxxxxxxxx
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Sorry for making noise, the mode is PV. Because my scheduler is set to
CPU fairness only, so the number I calculated is almost the same, as
long as I set it to I/O favor, the number is different.

Here is another question, since we always say a short period of time,
how long it should be? 500us? 50us? 1ms? is there any hint that I can


> Remind me, are you running in HVM mode, or PV mode?
> That sounds unusual.  Is it the number of events delivered, or the
> number of times the guest woke up?  NB they're not the same -- an HVM
> guest will block and then wake up on the completion of an I/O
> instruction which is handled by qemu.
> If you're running in HVM mode, you can use "xenalyze -s" will give you
> a summary of the trace.  In the summary you can see not only now many
> times a VM woke up, but which interrupt was delivered how many times.
> At the moment, from Xen's perspective, an event delivery is an event
> delivery.  You'd have to manually add some way of classifying an event
> as "I/O".
>  -George

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