[Pdns-users] Performance?

[Mike Benoit]

On Fri, 2003-04-04 at 12:37, David A. Ulevitch wrote:
> <quote who="Mike Benoit">
> 
> > We set our cache to timeout after 1day,
> > but to still get instant updates, we simply push cache expiration
> > commands to PDNS. (pdns_control purge www2.blah.com) This gives you the
> > best of both worlds and you should be able to scale PDNS well past
> > thousands of queries/sec.
> 
> *very* clever.
> 
> Are there any downsides to this that you've noticed?  I may script our code to
> run the purge on updates and set the cache timeout to a day also.
> 

The only downside we have noticed is if your cache becomes very large
(ours gets to about 1.2million entries), purging could start to take a
little while. We've seen it as high as 2seconds per purge command (purge
does use quite a bit of CPU during this process too). So this won't run
300/sec, but you can do things like purge domain.com and it will purge
all records for domain.com. Or of course www.domain.com to be more
specific, and only purge exact records.

If your really nice, you might be able to convince Burt to improve the
cache purging. ;)

We only make about 100-200 changes per _day_, so this works really well
for us, your mileage will of course vary.


> -davidu
> 
> 
> ----------------------------------------------------
>    David A. Ulevitch -- http://david.ulevitch.com
>   http://everydns.net -+- http://communitycolo.net
> Campus Box 6957 + Washington University in St. Louis
> ----------------------------------------------------
-- 
Best Regards,
 
Mike Benoit
NetNation Communications Inc.
Systems Engineer
Tel: 604-684-6892 or 888-983-6600
 ---------------------------------------
 
 Disclaimer: Opinions expressed here are my own and not 
 necessarily those of my employer