RE: [Xen-users] Slow windows network with gplpv driver.

["James Harper" <james.harper@xxxxxxxxxxxxxxxx>]

> 
> This concerns an old problem
>
http://lists.xensource.com/archives/html/xen-users/2010-08/msg00567.html
> 
> Still having the problem with network performance but need to really
fix it.
> 
> Just did a test with 32 bit xp with 0.11.0.238 drive.
> it show device as Xen Net device driver.
> 
> Iperf gives 14.7 Mbits/sec
> 
> Running an xp live boot cd  get 13.6 Mbits/sec
> Doesn't looks like the the pv driver is doing anything to help the
network as
> there is probably extra load with no pv drivers for disk and display.
> 
> How much of a speed improvement are others seeing?
> 
> The real issue is speed for samba shares.
> 
> I have tried on other hardware and it's a bit faster but not that
impressive.
> To keep the speed in perspective this is /proc/cpuinfo
> 

XP is probably a poor benchmark for GPLPV (or even without) for a few
reasons. If you want to get decent performance out of XP, disable the
firewall service (in services, not just in the network control panel)
and append " /PATCHTPR" to the boot.ini entry if using GPLPV. The
problem with XP is that it makes _very_ frequent calls to change and
read the TPR (Task PRiority) register, which incurs quite a bit of
overhead. "/PATCHTPR" avoids that completely on AMD hardware and
optimises the read case on Intel hardware, although I think Intel under
Xen may not suffer so badly these days.

I'm seeing a few gigabits per second when doing DomU<->Dom0 testing, and
full hardware speeds when talking over a physical network adapter when I
last tested.

James


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