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Date: Thu, 21 Jul 2005 23:14:32 +0200
From: Fabrice Bellard <fabrice@bellard.org>
Subject: Re: [Qemu-devel] Can you commit the pcnet patch ?
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To: qemu-devel@nongnu.org

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.