Likwid is a set of easy to use command line tools for Linux. It supports programmers in developing high performance multi-threaded programs. "Likwid" stands for "Like I knew what I am doing". It contains the following tools: likwid-topology, which shows thread and cache topology; likwid-perfctr, which measures hardware performance counters on Intel and AMD processors; likwid-features, which shows and toggles hardware prefetch control bits on Intel Core 2 processors; likwid-pin, which pins a threaded application without touching its code (it supports pthreads, Intel OpenMP, and gcc OpenMP), likwid-powermeter which prints the Turbo mode steps and measures energy consumption on supported Intel processors, and likwid-bench, a low level benchmarking framework. It works with any standard Linux kernel. Likwid is lightweight and adds no overhead during measurements.