Hello there,
I have been using polygraph to test a home grown cache on
a machine with lot's of RAM and fast CPU (but
not enough disk for such rate - the hit rate eventually settles to 30%).
I'm using variants of the polymix-2 workload with version 2.2.9.
I have the following problem. After several hours of operation (> 2days)
at a load of 200 request/second (which is supposed to be
constant after the first 30min) polygraph reduces the offered rate
gradually down to ~150req/second (all the time req.rate and res.rate
go hand in hand). At the moment the decline starts,
the wait.level.mean graph shows rapid increasing trend
(and conn.*.level.mean also show increasing tendency, although
nothing excessive)
Throughout the run there are also a few errors (total of 0.02%)
I'm wondering whether the problem is because of a flaw in the
box that makes the performance deteriorate and forces polygraph
to react accordingly, or an experiment miscofiguration since
I have taken a couple of liberties with the configuration that might be
the cause of the problem. Namely:
1) use robot cloning on the same IP address rather than that
configuring IP aliases
2) use fewer server agents than perscribed by the formula
in http://polygraph.ircache.net/Workloads/PolyMix-2/
(about 20 server agents, again on one IP but bound on different ports).
I know that taking such liberties does not produce the most accurate
testing environment, but had served its purpose to me so far for
shorter runs.
So if it's a configuration problem, why is it doing ok up to that
point and deteriorates later?
Thank you for your attention
Sincerely,
Kostas
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