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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