On Thu, Oct 16, 2003 at 05:18:24PM -0400, Robert Watson wrote: > > My conclusion from my BPF bridge experience was that prototyping in > userspace made it a lot easier to experiment with changes, and > dramatically reduced the development time. On the other hand, it did > terrible things to performance on high bandwidth tests, and because we > weren't using mbufs in userspace, made it harder to port to the kernel. > One nice benefit, though, was that we had TCP/IP people programming TCP/IP > stuff without having to teach them about mbuf semantics or kernel > debugging :-).
It's actually not so hard to get kernel mbuf-oriented code running in userspace. I did a userspace PPP implementation in 1994, and when it came time to do VJ compression I took the BSD kernel VJ code (from lbl.gov, if I recall correctly), defined some of the mbuf fields in my own structs, and it compiled and worked correctly without changing a single line of the VJ code. That project would never have survived if every bug had caused a kernel panic. The code is still running in commercial service today. -- Barney Wolff http://www.databus.com/bwresume.pdf I'm available by contract or FT, in the NYC metro area or via the 'Net. _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "[EMAIL PROTECTED]"
