[kwlug-disc] KVM

[L.D. Paniak]

It is not slow for processes which stay on the CPU and in RAM when VT-x
is turned on.

I just ran a LINPACK benchmark (HPL) on a single core/1GB VM (VirtualBox
3.1.6 - ubuntu 10.04 standard issue).  The quick result was 3.59
GFLOP/s.

The same benchmark running physically on a single core of the host
hardware gives: 3.78 GFLOP/s.

That is 95% efficiency.

I find disk I/O is the killer of virtual machine performance. Latency in
virtual networking is pretty abysmal as well, but I've never seriously
taxed throughput enough to say if it is a bottleneck. 


On Wed, 2011-01-26 at 17:32 -0500, Paul Nijjar wrote:
> On Wed, Jan 26, 2011 at 01:49:51PM -0800, William Park wrote:
> 
> > For speed, forget it.  They are dog slow.
> 
> I thought one of the selling points of KVM was to take advantage of
> the VTx extensions? 
> 
> Do you know what makes them slow? RAM? Hard disk contention?
> 
> - Paul
> 
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