On 13/01/14 01:16, Doug Barton wrote:
Howdy,
Without going into too much detail, doing some performance testing and
am seeing a weird result. On the same systems authoritative queries will
happily peg the CPU. However when running recursive queries (with a
small zone, all data cached before testing) the CPU never gets above
80%. The disk is nearly inactive on both systems, and there is no
swapping. Using BIND 9.9.4.
Is there perhaps something obvious I'm overlooking here? Any suggestions
are welcome.
I'm wondering if it's something tediously low-level like scheduler,
issues relating to concurrency/locking of the cache, and so on.
Presumably bind has some method to protect the cache from simultaneous
updates that requires some degree of locking - perhaps you're loading it
to a degree that you're bumping into lock waiting?
What's the (relative) size of the auth vs. pre-loaded recursive cache?
A generic CPU tracing tool (e.g. "perf" under Linux) might be able to
tell you the hotspots in the two cases, and any differences might be
instructive.
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