[dns-operations] Writeup of Spring Workshop

[Paul Vixie]

Ralf Weber wrote:
> Moin!

gack!

> ...
>
> So as said we agree that the Community should put more effort in 
> getting the Linux people to do better UDP stack instead of switching 
> DNS to TCP, which other people have been suggesting.

on a 1.4-GHz opteron in 2003 or so, recvmsg/sendmsg was giving us ~30K
UDP TPS. there was no recvmmsg() at that time. this was freebsd 5 or so.

so we wrote a user mode UDP implementation that was based on BPF,
knowing that the syscall interface used by libpcap received up to 50
packets per call.

we got 200K UDP TPS.

so, i'd be very curious to see a linux-vs-freebsd UDP bakeoff (just
using recvmsg/sendmsg) since i know that both kernels have had a great
deal of performance work done to their UDP stacks in the past decade.

and i'd be very curious to see a recvmsg-vs-recvmmsg UDP bakeoff, since
if there isn't a huge speedup from using recvmmsg, then the locking in
the kernel is still too course-grained. (this test would have to be run
separately on linux and on freebsd, since they obviously use different
kernels.)

-- 
Paul Vixie