When talking about perf in Linux, it actually refers to 2 things:
a) Perf_events (also be called as perf for short): a subsystem which was merged into Linux kernel since 2.6.31;
b) A powerful and comprehensive user-space tool: perf, which leverages perf_events subsystem to do performance analysis.
Perf is a really powerful tool. As Brendan Greeg wrote in his Choosing a Linux Tracer (2015):
If there's one tracer I'd recommend people learn, it'd be perf, as it can solve a ton of issues, and is relatively safe.
In this small tutorial, I will give a whirlwind tool of the user-space perf utility.