Re: [Xen-users] More Windows network performace issues.

[John McMonagle <johnm@xxxxxxxxxxx>]

On Friday 15 April 2011 07:34:06 am James Harper wrote:
> > Made considerable progress with networking problems.
> > New anti-virus and new gplpv driver helped a lot.
> >
> > I'm still having poor speed to the external network.
> >
> > Dom0 is debian squeeze using the debian dom0 kernel. Xen is 4.0.1 from
>
> source.
>
> > Tested domu windows in server 2008 with new gplpv drivers.
> > Reference debian pv domu is debian squeeze.
> > All are 64 bit.
> > External site is a xen dom0 as it's the fastest available.
> > All tests with iperf in Mbits/sec
> > Did each a few times and they were pretty consistent.
> > I put down the highest number.
> >
> > domu server 2008 > dom0   618
> > domu server 2008 > external 280
> > domu server 2008 > domu squeeze  533
> > domu squeeze > dom0   4000
> > domu squeeze > external  923
> > dom0 > external   933
> >
> > The one that concerns me is:
> > domu server 2008 > external 280
> >
> > Need to access external file shares and that is quite a hit.
> > Why does a hvm domain take an additional hit in the bridging to the
>
> external
>
> > interface?
> >
> > Any ideas?
>
> I'm getting similar results. About 1GBits/second to Dom0 and
> 200MBits/second to an external host (over gigabit).
>
> I just tested an XP machine and got the following with -w1m -l32k
> options to iperf:
> (Ext is just a gigabit LAN to another Xen physical machine)
>
> DomU -> Dom0 - 5Gbits/second
> Dom0 -> DomU - 800Mbits/second
> Dom0 -> Ext  - 940Mbits/second
> Ext  -> dom0 - 950Mbits/second
> DomU -> Ext  - 930Mbits/second
> Ext  -> DomU - 950Mbits/second
>
> So it does seem to be 2008 specific.
>
> The problem you are seeing may be something to do with the fact that
> under Vista and above, Windows has to use a compatibility layer to make
> my NDIS5.1 driver work at all. The fact that a driver written for an 8
> year old OS works at all says something about Microsoft's commitment to
> backwards compatibility, but there are definitely some performance costs
> associated with it. I don't understand why it would be slower to an
> external host though.
>
> One of these days I'll port xennet to NDIS 6.x and I hope to see some
> fairly impressive performance increases, but I just don't have the time
> right now, plus it means maintaining two versions of xennet etc.
>
> James
James

This test is windows 7.  1 cpu.
Server 2008 looks about the same.
Figured windows 7 is a simpler case.
Also odds are your server is faster.

Also have an xp domu on that server for testing.
 to dom0 147   
to external   90.1
With your parameters for iperf
to dom0 536   
to external   388

You sure have xp working better than I have.
I'll experiment on them a little more.
I see change to windows7 and server 2008 coming.

Seems  strange.  As a person that really knows nothing about the actual code 
looks like the hvm domain is connected into the network differently than a pv 
domain.  At least the problem looks less severe.

Just redid windows test with your parameters.
to dom0   1870
to  domu  2000
to ext      745

Much better.
Are the defaults for iperf for windows different that for linux?
I'll retest my other windows installations.

John

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