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Re: [Xen-devel] Credit scheduler


  • To: <pak333@xxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: Keir Fraser <keir@xxxxxxxxxxxxx>
  • Date: Wed, 27 Jun 2007 02:17:32 +0100
  • Delivery-date: Tue, 26 Jun 2007 18:15:34 -0700
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: Ace4WO+cLmdT0iRMEdyu6gAX8io7RQ==
  • Thread-topic: [Xen-devel] Credit scheduler

Are these all Windows HVM guests? And do you exclude domain0 when you count the number of VMs in your system (so it’s actually 4 user VMs + domain0 VM)? How did you come up with the 3us figure — some kind of in-guest tracing, or using xentrace, or by some other means?

Does the problem still happen if you run 2 cpu-intensive VMs instead of 3?

 -- Keir

On 27/6/07 02:09, "pak333@xxxxxxxxxxx" <pak333@xxxxxxxxxxx> wrote:


I have 4 physical cpus (2 dual core sockets) and the IO workload is loadsim with 500 users

Thanks
-Prabha


 -------------- Original message ----------------------
From: Keir Fraser <keir@xxxxxxxxxxxxx>
> How many physical CPUs do you have, and what is the IO workload that one of
> the VMs is running?
>
>  -- Keir
>
> On 26/6/07 22:33, "pak333@xxxxxxxxxxx" <pak333@xxxxxxxxxxx> wrote:
>
> > Hi
> >  
> > I have noticed that VMs are typically spending 3 microsecs or less before they
> > are being prempted. I thought that the credit schduler time slice was 30 ms. I
> > have 4 VMs running and they are all cpu intensive except for 1 (which is IO
> > intensive) but having a VM spend max 3 micro secs before being kicked out
> > seems strange.
> >  
> > Is there something else going on that i am not aware of. Is the time slice
> > really 30 millisecs? I am using default parameters of the credit scheduler.
> >  
> > Thanks
> > -Prabha
> >  
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
>
>



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