adding per to my toolbox

[ruebenramirez]

Ms. Evans posted about using perf: http://jvns.ca/blog/2016/02/24/perf-top-my-new-best-friend/

She links to these guys also:

• http://www.brendangregg.com/perf.html
• http://techblog.netflix.com/2015/07/java-in-flames.html