moseleymark at gmail.com
Thu Jul 6 19:24:23 UTC 2006
On 7/6/06, bert hubert <bert.hubert at netherlabs.nl> wrote:
> On Thu, Jul 06, 2006 at 11:03:14AM -0700, Mark Moseley wrote:
> > Just a quick question regarding the excellent pdns-recursor:
> Thanks :-)
> > To save myself a number of days of trial and error, I'm curious if
> there's a
> > rough conversion for max-cache-entries => memory limit of cache.
> > it's not going to be exact but is there a maximum limit in bytes of each
> > cache entry, so that max-cache-entry x max-cache-entries = Max memory
> > for cache?
> No, there is no hard and fast rule. *Actual* memory use depends on a lot
> things, including c++ compiler, operating system paging strategy, access
> From what I know, 4 million cache entries correspond to around 1G of
> used. From my measurements, there is not a lot of benefit of using more
> 4 or 5 million entries, generally.
> On 64 bit systems, some more memory will be needed because of the 8 byte
> pointers. This has been confirmed by some large operators.
> Tinydns is able to do exact bytewise limiting of memory usage, which is
> impressive. I've pondered doing something like it but it requires a lot of
> very tricky coding, so the current cache entries limit will have to do.
> Good luck!
> http://www.PowerDNS.com Open source, database driven DNS Software
> http://netherlabs.nl Open and Closed source services
Cool, that gives me round numbers to work with. Thanks for the info!
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