# NetMP 

[What's this all about?](http://leaf.dragonflybsd.org/mailarchive/kernel/2008-04/msg00093.html)

## new sockbuf 

Why do we want to change the sockbuf implementation? Look [here](http://leaf.dragonflybsd.org/mailarchive/kernel/2008-05/msg00003.html).

You can find the new sockbuf code in the 'sockbuf' branch at http://repo.or.cz/w/dragonfly/netmp.git

 **UPDATE** : switched the sockbuf branch to a new semi-lockless sockbuf implementation
by Matthew Dillon. Still pondering about a different linked-list implementation (M_CORAL, this is probably only meaningful if you've followed the discussion on irc) without the added indirection through the cupholders.

Cupholder pros:

* working code available now

* dynamically sized

* simple implementation
Cupholder cons:

* extra memory references

* larger cache footprint

M_CORAL pros:

* dynamically sized
M_CORAL cons:

* complex code

* maybe issues with deallocating mbufs w/ an attached cluster

Ring buffer pros:

* cache efficient

* very straightforward code
Ring buffer cons:

* incurs 8K overhead for every socket (I think I can make it dynamically sized; not sure about code complexity then though)

My plan is to use the cupholder implementation for now and revisit this later. The APIs are
largely compatible anyway.

 **XXX** : the rest of this section refers to the ring buffer implementation

If you want to do some testing, you can follow [these instructions](http://leaf.dragonflybsd.org/mailarchive/kernel/2008-06/msg00085.html). 
Some modules and a few userland utilities don't know about the new sockbuf yet, so please only try to build the kernel as described in the mail above.

Known issues:

* nfs occasionally thinks the server has gone down. Recovers almost instantly, but nativekernel time is still affected

* http accelerator doesn't even compile

* smbfs is probably broken, haven't tested at all

* ncp, ipx, Xerox NS are broken; won't fix because: not relevant any more, no users, no way to test (UPDATE: except Jonathan Stuart [cares](http://leaf.dragonflybsd.org/mailarchive/kernel/2008-06/msg00113.html) for IPX).

* sctp is 'special'. Thomas Nikolajsen [volunteered](http://leaf.dragonflybsd.org/mailarchive/kernel/2008-06/msg00121.html) to work on SCTP after the 2.0 release which is just as well, since I don't plan to put in the new sockbuf code until we brach for 2.0

* unix domain sockets also not well tested

* ->rbytes, ->wbytes wraparound not tested

* based on a snapshot from May 6th; need to merge with CVS HEAD

Stuff that's expected to work:
ftp/http/ssh/nfs/dns/ping

## tcpcb 
An overview of the problems with accesses to the tcpcb can be found in [this](http://leaf.dragonflybsd.org/mailarchive/kernel/2008-06/msg00055.html) message.

Accesses to the tcpcb now always go through the protocol thread. Work started [here](http://leaf.dragonflybsd.org/mailarchive/commits/2008-06/msg00123.html), was revised
[later](http://leaf.dragonflybsd.org/mailarchive/commits/2008-07/msg00055.html) and I [fixed](http://leaf.dragonflybsd.org/mailarchive/commits/2008-07/msg00104.html) the last
known bugs shortly afterwards.

## UDP inpcb 
See the subthread starting [here](http://leaf.dragonflybsd.org/mailarchive/kernel/2008-06/msg00057.html).

## socket 

Start by reading [this](http://leaf.dragonflybsd.org/mailarchive/kernel/2008-08/msg00037.html) mail; needless to say, my analysis was not entirely spotless. Taking into account Matt's [suggestions](http://leaf.dragonflybsd.org/mailarchive/kernel/2008-08/msg00040.html), work has been ongoing in the socket branch in the netmp repo (see above). Also see the rest of the thread. The rest of the socket fields (except ->so_oobmark) are discussed [here](http://leaf.dragonflybsd.org/mailarchive/kernel/2008-08/msg00065.html).