Re: Question about the ability of credit scheduler to handle I/O and CPU intensive VMs

[George Dunlap <George.Dunlap@eu.citrix.com>]

I think this is probably an area open for research. :-)

I would think 500us or 1ms would be decent options, but that's mostly a 
guess.

  -George

On 12/10/10 13:42, Yuehai Xu wrote:
> 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
> follow?
>
> Thanks,
> Yuehai
>
>
>>
>> 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
>>