FreeBSD bind performance in FreeBSD 7

Kris Kennaway kris at FreeBSD.org
Mon Feb 25 20:17:58 UTC 2008


Oliver Herold wrote:
> Hi,
> 
> I saw this bind benchmarks just some minutes ago,
> 
> http://new.isc.org/proj/dnsperf/OStest.html
> 
> is this true for FreeBSD 7 (current state: RELENG_7/7.0R) too? Or is
> this something verified only for the state of development back in August
> 2007?

I have been trying to replicate this.  ISC have kindly given me access 
to their test data but I am seeing Linux performing much slower than 
FreeBSD with the same ISC workload.

   http://people.freebsd.org/~kris/scaling/bind-pt.png

Summary:

* FreeBSD 7.0-R with 4BSD scheduler has close to ideal scaling on this test.

* The drop above 6 threads is due to limitations within BIND.

* Linux 2.6.24 has about 35% lower performance than FreeBSD, which is 
significantly at variance with the ISC results.  It also doesn't scale 
above 3 CPUs.

* I am trying to understand what is different about the ISC 
configuration but have not yet found the cause.  They were testing 
2.6.20.7 so it is possible that there was a major regression before the 
2.6.22 and .24 kernels I tested.  Or maybe something is broken with the 
Intel gige driver in Linux (they were using broadcom hardware).  The 
graph is showing performance over 10ge, but I get the same peak 
performance over gige when I query from 2 clients (the client benchmark 
is very sensitive to network latency so a single client is not enough to 
saturate BIND over gige).

* 7.0 with ULE has a bug on this workload (actually to do with workloads 
involving high interrupt rates).  It is fixed in 8.0.

* Changes we have in progress to improve UDP performance do not help 
much with this particular workload (only about 5%), but with more 
scalable applications we see 30-40% improvement.  e.g. NSD 
(ports/dns/nsd) is a much faster and more scalable DNS server than BIND 
(because it is better optimized for the smaller set of features it 
supports).

Kris




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