Van Jacobson's network stack restructure

[Mike Silbersack]

On Wed, 1 Feb 2006, Greg 'groggy' Lehey wrote:

> Last week, at the Linux.conf.au in Dunedin, Van Jacobson presented
> some slides about work he has been doing rearchitecting the Linux
> network stack.  He claims to have reduced the CPU usage by 80% and
> doubled network throughput (he expects more, but it was limited by
> memory bandwidth).  The approach looks like it would work on FreeBSD
> as well.  I spoke to him and he confirmed.
>
> He's currently trying to get the code released as open source, but in
> the meantime his slides are up on
> http://www.lemis.com/grog/Documentation/vj/.  Yes, this is my web
> site.  The conference organizers are going to put it up on their web
> site soon, but in the meantime he's asked me to put it were I can.
>
> Comments?
>
> Greg

The slides alone don't tell much.  There seem to be two possibilities - 
either "channelizing" everything is responsible for the improvements, or 
the fact that it waits until the socket is woken up to process the packets 
is responsible for the improvements.  I can't understand why the final 
step involves a userland TCP stack.  The rest of the presentation doesn't 
explain why that is necessary.

I'm sure we'll learn more once we see the source.

Mike "Silby" Silbersack