[Pdns-users] pdns-recursor cache settings

[Tomasz Kawalec]

Hello,
          I've a question about pdns-recursor and its settings. I've a
pdns-recursor running with 4 threads. I'm trying to set up the best
performance setting and I'm confused about the max-(packet)cache-entries
settings. In the performance guide (
http://doc.powerdns.com/html/recursor-performance.html) it is said that:

"Limit the size of the caches to a sensible value. Cache hit rate does not
improve meaningfully beyond 4 million max-cache-entries per thread,
reducing the memory footprint reduces CPU cache misses. See below for more
information about the various caches. "

Does it mean if I want 4 million `max-cache-entries` per thread with 4
threads running I've to set `max-cache-entries` to 4000000 (4M) or 16000000
(16M)?

How can I interpret these example settings with `threads` set to 4?
a) max-cache-entries = 4000000
b) max-packetcache-entries = 1000000

Means:
a) Each thread will have the limit of 4000000 entries or 1000000 entries?
b) Each thread will have the limit of 1000000 entries or 250000 entries?

I've studied the documentation and I can't find an answer to my question.
Please answer if You are absolutely sure how those settings behave.

If anyone have experience in setting the threads/max-(packet)cache entries
for busy DNS environment and would like to share his settings with stating
average qps from hosts will be appreciated. Best Regards.
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