Re: [Qemu-devel] Can you commit the pcnet patch ?

[Fabrice Bellard]

Paul Brook wrote:
> On Thursday 21 July 2005 08:29, Lars Munch wrote:
>
> > On Wed, Jul 20, 2005 at 12:32:10PM +0200, Ludovic Drolez wrote:
> >
> > > Hi !
> > >
> > > I've tried the latest AMD pcnet patch (made by Antony T Curtis) with qemu
> > > 0.7 because I was tired of the sloooww PXE booting of my QEMU. For
> > > exemple, to load a linux kernel + initrd over TFTP, it takes 4m30s with a
> > > ne2000, and 1m35s with the PCNET card.
> >
> > Does anyone know why pcnet is so much faster than ne2000? is it easier
> > to emulate? or is there room for improvements on the ne2000?
>
>
> Probably because it's a DMA capable controller. IIRC the ne2k is pio based, so 
> has to shuffle the data through an IO port one byte at a time.

I don't think that the switch to DMA can explain a factor of 3. Another 
possibility is that there is a bug in the ne2000 code. It could be 
interesting to check the send and receive latencies by adding traces in 
the ne2000 code...

Fabrice.