http://www.brendangregg.com/USEmethod/use-linux.html http://www.brendangregg.com/usemethod.html
http://www.brendangregg.com/tsamethod.html
http://fractio.nl/2008/03/22/practical-performance-monitoring-tooling-on-linux/
measure memory use in Python: https://news.ycombinator.com/item?id=27738566