in-kernel tcp server

[Nicolas Cormier]

On 6/20/07, John Polstra <jdp at polstra.com> wrote:
> Julian Elischer wrote:
> > Nicolas Cormier wrote:
> >> Hi,
> >>
> >> I'm trying to write a little tcp-server kernel module (like tftp).
> >> I didn't find a lot of documents about the kernel network programming,
> >> just one thread which talks about netgraph.
> >> In the freebsd includes I found /usr/include/sys/socketvar.h (so*).
> >>
> >> What's the easy way to create a basic tcp server
> >> (create/bind/listen/accept/send/recv) : use netgraph's ksocket or so*
> >> ?
> >>
> >> Thanks in advance !
> >> PS: the whole job must be done in the kernel.
> >
> >
> >
> > yes it can (and has been) done..
> > John Polstra did it many years ago.. using netgraph ksockets.
> > He had an in-kernel web server.
> > At least I THINK it was him :-)
>
> Yes, that's right.  I started out using netgraph ksockets, but later on
> it evolved, mainly for performance reasons.  (I needed it to be really,
> really fast.)  The first change was that I eliminated the ksockets and
> worked directly at the link layer, using ng_ether nodes.  I implemented
> a small, stripped down TCP stack and bypassed the FreeBSD native
> TCP/IP/socket layers.  This was still done with netgraph, using just the
> ng_ether nodes talking to my own ng_webclient / ng_webserver nodes.  It
> improved the performance immensely.
>
> More recently I restructured it quite a bit to get better MP performance
> using FreeBSD 7.x.  (The original version was based on 4.x).  I found
> that the netgraph locking and internode communication mechanism impacted
> performance too much under 7.x.  So I eliminated the ng_ether nodes and
> made the webserver / webclient nodes talk directly to the interfaces via
> the if_input / if_output hooks.  It still uses netgraph, but really only
> as a configuration and management mechanism.  No actual network traffic
> flows between netgraph nodes.  This change also resulted in a big
> performance improvement.

Thx, I have started with ng_ksockets, for the now it is sufficient.

> Unfortunately, my contract forbids me to release the source code publicly.

Bad news !
Thanks a lot for your answer, a last question "why did you not used
so* functions ?"
-- 
Nicolas Cormier