Re: [Xen-users] Re: I/O performance.

["Tim Wood" <twwood@xxxxxxxxx>]

One thing I've noticed is that if you have 2 VMs on a server and one
is running a IO intensive task while the other is CPU intensive, the
IO task tends to get starved and performs very poorly.  This seems
like a scheduling problem, so perhaps the new credit scheduler helps
with this, although I haven't tried.

So to further complicate how to measure I/O performance there is the
issue of interference with other VMs.


On 8/28/06, Sven Köhler <skoehler@xxxxxx> wrote:
> > What performance penalty I should expect from the I/O under domU ?
> >
> > Does it matter to the I/O if the CPU has hardware virtualization ?
>
> Me, personally, would be interested in the performance in the case that
> the DomU accesses a block device on the host though the "most optimized"
> case - namely if the DomU is using the Xen frontend and the Xen backend
> of the Dom0 to access the device.
>
> There are many questions, like:
> Does Xen allow the DomU to make multiple requests that are then queued
> on the Dom0 or even passed to the lower level SCSI/SATA driver of the
> Dom0? And so on ...
>
>
>
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