RE: [Xen-users] GPLPV network performance

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

> On Mon, 19 Jan 2009, Grant McWilliams wrote:
> 
> > It seems the speed issues are with data entering the DomU and not
> > actually DomU to DomU performance. Can you guys test Dom0 to DomU
speed
> > instead of the other way around.
> 
> Dom0 2.33 GHz Intel Core2, CentOS 5.2, xen 3.0.3, GPLPV 0.9.12-pre13:
> 
> Windows XP SP3:
>       server=Dom0 client=DomU 702 Mbits/sec
>       server=DomU client=Dom0 667 Mbits/sec (5% slower)
> 
> Windows 2003 SP2:
>       server=Dom0 client=DomU 1.02 Gbits/sec
>       server=DomU client=Dom0 719 Mbits/sec (29% slower)

Just FYI, the reason for the performance drop in the domU RX path is
that Windows doesn't support some of the offload functions that Linux
does, so I have to emulate them which has some pretty high overhead,
mostly related to packet copying.

In fact in the RX path, there is quite a lot of copying going on and
there is definitely room for improvement, but it will never be as good
as TX.

James

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