I've recently been paying some attention to this tool. I've discovered some bugs and some great room for improvements. Basically I found that the rps metric was not very precise and also that the performance of the application was not very good. Regarding the requests per second issue, I changed the way they are calculated and now I can grant that the results are quite accurate (compared to what I see in the log files of the benchmarked server). I've also found that the performance was quite bad, mainly because of the python threading system and the python GIL. So I decided to migrate the tool to python multiprocessing and the performance improvements have been huge: almost 3 times faster. As I was already changing things I also changed the plotting library from gnuplot to matplotlib as gnuplot wasn't very stable. This also implies that the plot cannot be viewed live anymore and the "-l" option will now allow you to play with the plot once the benchmark is done. Also, now the tool should work properly in systems with out xserver.
Please, be aware that you need a big server (several cores, big bandwidth, etc) in order to benchmark a website properly instead of end up benchmarking the tool itself or your bandwidth connection. I will still work in this tool in the future and one of the things I would like to do is to make it distributed so it can run a benchmark from different servers and then gather all the results in a central node. This would help to eliminate bottlenecks in the client side of the benchmark.
Please, if you use the tool report any bug you see and of course let me know if you see how to improve the tool. All comments are welcome :).
You can already find this new version at: https://github.com/diego-XA/dgtool/tree/master/pywench