The PERF tool is a part of the Linux kernel since version 2.6. This tool is an event-based profiler and observability tool. It can count various event occurrences in the system, from hardware performance monitoring unit (PMU) events of the CPU at one end, to software tracepoints at the other. It can trace both kernel and userspace functions. The tool is very useful to kernel and application software developers, as well as hardware designers. This thesis aims at describing the PERF tool from the point of view of a PERF test engineer. Additionally, it is also about designing methods for verification of its correct functionality.