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From "Baskar Duraikannu" <baskar.duraikannu...@gmail.com>
Subject Re: Performance tests using stress testing tool
Date Fri, 29 Apr 2011 13:14:02 GMT
Thanks Peter. I am using java version of the stress testing tool from the contrib folder. Is
there any issue that should be aware of? Do you recommend using pystress? 

I will rerun tests in order to monitor ethernet stats closely and will update.

--
Thanks,
Baskar Duraikannu 


----- Original Message ----- 
From: Peter Schuller 
To: user@cassandra.apache.org 
Sent: Thursday, April 28, 2011 1:21 PM
Subject: Re: Performance tests using stress testing tool


> When I looked at the benchmark client machine, it was not under any stress
> in terms of disk or CPU.

Are you running with the python multiprocessor module available?
stress should print a warning if it's not. If it's not, you'd end up
with a threaded mode and due to Python's GIL you'd be bottlenecking on
CPU without actually using more than ~ 1 core on the machine.

> But test machines are connected through 10/100 mbps switch port (not
> gigabit). Can this be a bottleneck?

Maybe but seems not-so-likely unless you've turned up the column size.
Check if 'ifstat 1' if you're pushing lots of data.

Another possibility is that the writes are periodically blocking due
to compaction (and compaction is not yet parallel unless you're
running 0.8 betas). However this should show up in the stress client
by a period lack of progress; it shouldn't give you a smooth amount of
cpu usage over time.

-- 
/ Peter Schuller

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