DNS query performance

[Robert Watson]

On Mon, 11 Sep 2006, Marcelo Gardini do Amaral wrote:

> I would like to discuss a little bit more about UDP performance. I've made 
> some tests and the results may have some value here.
>
> In this test is easy to see that there is something different in the FreeBSD 
> 6 branch.
>
> I made a benchmark with bind 9.3.2 (without threads support) and nsd 3.0.1 
> (1 server forked) on a HP Proliant Dual AMD Opteron 2.4GHz among FreeBSD 
> 4.11, 6.1 and Linux kernel 2.6.15, all of them for i386 systems. I used this 
> simple zone file:

Are you able to boot a 7.x kernel on this box?  An as yet un-MFC'd 
optimization to the UDP send path is present in the 7.x kernel, suggested by 
ISC, which significantly improves threaded BIND9 performance.  I've not 
benchmarked unthreaded BIND9 with the change.  If you want to test 
specifically the before/after case for that change, you can find the reference 
to sosend_dgram in src/sys/netinet/udp_usrreq.c and swap it to sosend, which 
restores the old behavior.

Robert N M Watson
Computer Laboratory
University of Cambridge