Re: [Xen-devel] what's maximum speed setting for xen network?

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

It is possible to rate limit vifs but it won't be active by default.

What are you using to copy the files across?  If you're using scp, bear in 
bind that both virtual machines will have to do crypto, so you could actually 
be limited by CPU performance rather than virtual network.

Also, uniprocessor systems are a worst case for this sort of test because 
you'll incur a lot of context switches.  Hyperthreading should be able to 
mitigate this somewhat.

There are plans to optimise host-internal networking somewhat.

Cheers,
Mark

On Friday 22 April 2005 21:14, Xin Zhao wrote:
> I just setup network and tried to copy files between dom0 and domU. The
> speed is around 100Mb/s. So I once thought it is simulating 100Mb network,
> but after looking into the network driver, I failed to find anything about
> the flow control.
>
> I didn't try UDP, so have no idea about UDP losses.
>
> Xin
>
> On Fri, 22 Apr 2005, mukesh agrawal wrote:
> > > For a physical network card, it has a maximum transmission speed such
> > > as 100Mb. How about network in a virtual machine? It is a virtual
> > > network card. Is there any speed limit? Or it can transmit as fast as
> > > possible? If so, I guess network transmission happened within a
> > > physical host should be very fast (great than 100Mb). But this is not
> > > true in my experiment.
> >
> > Out of curiousity, what kind of testing have you run, and what kind
> > of speeds are you getting?
> >
> > I've got a configuration with DomU talking to Dom0 over a vif, and seem
> > to be seeing UDP losses, even at low data rates. (I haven't dug into this
> > deeply to very the problem yet, though.) So I'd be interested if you're
> > seeing something similar.
> >
> > Thanks,
> > mukesh
> >
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