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From Peter Schuller <peter.schul...@infidyne.com>
Subject Re: what causes MESSAGE-DESERIALIZER-POOL to spike
Date Tue, 27 Jul 2010 07:28:03 GMT
> average queue size column too. But given the vmstat output I doubt
> this is the case since you should either be seeing a lot more wait
> time or a lot less idle time.

Hmm, another thing: you mention 16 i7 cores. I presume that's 16 in
total, counting hyper-threading? Because that means 8 threads should
be able to saturate 50% (as perceived by the operating system). If you
have 32 (can you get this yet anyway?) virtual cores then I'd say that
your vmstat output could be consistent with READ-ROW-STAGE being CPU
bound rather than disk bound (presumably with data fitting in cache
and not having to go down to disk). If this is the case, increasing
read concurrency should at least make the actual problem more obvious
(i.e., achieving CPU saturation), though it probably won't increase
throughput much unless Cassandra is very friendly to
hyperthreading....

-- 
/ Peter Schuller

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