Tuesday, 19 February 2008

Lyme vs Lamp III

Lyme vs Lamp continues...

I've been spending some time figuring out how Tsung outputs the data, how gnuplot works and how to create my own graphs using the Tsung output data. I now have a graph that shows the throughput rate (Kbits per second) and the arrival rate of users.

When you set up the testing scenarios using Tsung, you can specify the arrival rate of new users. I've set up a simple progression, that changes every 60 seconds, going from 2 users per second up to 1000 users per second. You can see the progression in the graph below.

The page that is being requested is generated from an Mnesia database, with Yaws. The database contains 1000 made-up blog "postings", and the page requested renders the last 5 postings. The machine is quite old, a 2004 laptop actually, and Tsung is also running on the same machine as Lyme.

I've plotted the data throughput rate against the arrival rate. (I've used Inkscape to polish the gnuplot SVG output. I really love it and use it all the time). Here's the result:

As you can see, the throughput rate increases proportionally to the user arrival rate. The "server" manager to handle 200 users/sec, but with 500 requests per second the increase in rate is not proportional. Looks like the max has been reached. Increasing the request rate to 1000 requests shows no difference in throughput. Please comment if you have any more insight into the data.

I should be able to get a PHP version soon, so I can compare it against something...

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