Subject: Re: More performance for the TCP stack by using additional
	hardware chip on NIC
From: Avi Kivity <avi@argo.co.il>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Andreas Hartmann <andihartmann@01019freenet.de>,
       linux-kernel <linux-kernel@vger.kernel.org>
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	 <1113728880.17394.16.camel@laptopd505.fenrus.org>
	 <1113733753.15803.26.camel@avik.scalemp>
	 <1113735452.17394.33.camel@laptopd505.fenrus.org>
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Date: Sun, 17 Apr 2005 15:32:53 +0300
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On Sun, 2005-04-17 at 13:57, Arjan van de Ven wrote:
> > 
> > TOEs can remove the data copy on receive. In some applications (notably
> > storage), where the application does not touch most of the data, this is
> > a significant advantage that cannot be achieved in a software-only
> > solution.
> 
> other solutions can too. Search the archives for posts from Dave Miller
> and Jeff Garzik on these issues. Note that TOEs per se don't do this,
> specific treats of interfaces to TOE *may* allow this. The interesting
> part is that the parts of the interface that would allow this can be
> implemented without TOE (and all the downsides of full TOE such as
> bypassing firewall rules etc etc) just as well.
> 

I see. if you are referring to Willy's trick in the other post, then I
agree. it has still more overhead than full offload, so only
measurements can tell if it is enough (and, of course, need to wait for
the hardware to materialize).


> > a copyless solution is probably necessary to achieve 10Gb/s speeds.
> 
> I've heard the same say abot 100Mbit and 1Gbit. And neither has been
> proven true. Don't get me wrong, avoiding copies is always nice, and on
> sending linux already enables that (depending on the applications
> capabilities). But I personally find it hard to accept that full
> copyless operation is a strict requirement to achieve 10Gb/s.
> 
> What sure will be required to achieve efficient 10Gb/s performance is a
> whole lot of tuning in the network stack and potentially even in the
> tcp/ip layer to allow for bigger buffers etc. But I'm pretty sure that
> effort is underway already or will be soon...
> 

amen.

Avi

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