[Pdns-users] Performance of pdns authoritative server on big machines with different backends

Marc Haber mh+pdns-users at zugschlus.de
Wed Jan 5 08:56:55 UTC 2011


On Tue, Jan 04, 2011 at 09:17:48PM -0500, Mathew Hennessy wrote:
> Looks like in either case you're driving a ton of interrupts and
> context switches, which may be a driver issue if it's not a known
> issue with PDNS threading (and cursory googling doesn't have this leap
> out).  For example, I've used a Dell PERC RAID adapter in earlier
> Linux kernels that spiked the context switches and caused delays that
> a later card-specific driver patch from Dell fixed.  I would figure
> high wait times (wa) if it was an I/O issue to your drives though.

As I said in the thread starting article, the database fully fits into
memory, and during the benchmark the disk subsystem is (nearly) idle.
And, of course, benchmarking against the bind backend doesn't use the
disk at all.

> Given your PowerDNS run results, it looks like your bottleneck is in
> your NIC, perhaps you need to resize buffers and tcp settings? Here's
> a handy link for linux tcp tuning:
> http://fasterdata.es.net/TCP-tuning/linux.html

The benchmark uses UDP only. I fail to see what role TCP tuning plays
in the setting.


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