[Gllug] Constrained virtual machines

[Richard Huxton]

Daniel P. Berrange wrote:
> On Thu, Nov 30, 2006 at 03:05:11PM +0000, Richard Huxton wrote:
>> Is anyone using VM technology that provides limits on CPU and I/O as 
>> well as memory usage?
> 
> Xen gives you very good control over CPU scheduling of guests. Memory
> is reasonable - you can balloon up & down guest OS memory on the fly.
> With disk I/O there is near zero per-guest throttling / control, you
> really have to rely on the Dom0 OS doing reasonably fair I/O scheduling.

Blast. I'm after "unfair but under my control".

> Simiarly for network I/O, but at least for this you can use existing 
> IP traffic shaping utilities in Dom0 if you need to control it based
> on the MAC address of the guest OS.
> 
>> What I'd like to be able to do is run a set of database tests with 
>> varying configuration settings. I'm not really concerned with absolute 
>> numbers, but I'll need to scale CPU and I/O to generate some useful figures.
> 
> Xen will give you pretty good data for this - Database benchmarks are
> a test we run very frequently for Xen on RHEL-5 to verify performance
> is being maintained over course of development. Xen scales up quite
> nicely as you add extra CPUs, or as you add increasing number of guests
> doing same workload.
> 
> Make sure you use Xen 3.0.3 though - even just one minor release earlier
> with 3.0.2 had absolutely terrible scalability.

Thanks for the pointer.

-- 
   Richard Huxton
   Archonet Ltd
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