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Re: [Xen-devel] Xen & I/O in clusters - Single Vs. Dual CPU issue

To: Rune Johan Andresen <runejoha@xxxxxxxxxxx>
Subject: Re: [Xen-devel] Xen & I/O in clusters - Single Vs. Dual CPU issue
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Sat, 06 Nov 2004 08:04:47 +0000
Cc: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>, Xen Virtual Machine Monitor <xen-devel@xxxxxxxxxxxxxxxxxxxxx>, br260@xxxxxxxxx, Rune Johan Andresen <Rune.Johan.Andresen@xxxxxxxxxxx>, H=E5vard_Bjerke <havard.bjerke@xxxxxxxxxxx>
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In-reply-to: Your message of "Fri, 05 Nov 2004 18:33:09 +0100." <C2CAE713-2F50-11D9-8795-000A95B44940@xxxxxxxxxxx>
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Unless your workload maxes out one of the CPUs, or doesn't play as
well as it could with the CPU scheduler. In general it's probably wise
to run your dom0 on another CPU, or at least HyperThread, from other
performance-critical VMs. 

The situation on a single CPU should be improveable with tweaking,

 -- Keir

> Yes, I am running on a SMP system with two CPUs. The nodes are running 
> on different CPUs, but is this a problem? If the two
> guest OSs are unprivileged and run on separate CPUs, they should 
> perform I/O just as good (or bad) anyway, no?
> Cheers,
> Rune
> On Nov 5, 2004, at 5:47 PM, Keir Fraser wrote:
> >>
> >> A and B are domain 0, A1,A2,B1,B2 are the guest OS systems. I think 
> >> all
> >> are privileged (?), They are
> >> created with the same config file, exception of the file loopback
> >> configuration and ip config.
> >>
> >> Cheers,
> >> Rune
> >
> > Are you running on SMP systems? I would guess the performance differs
> > based on whether DOM0 and the unprivileged guest are runnign on the
> > same CPU or different CPUs...
> >
> >  -- Keir

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