perf (sometimes called "Perf Events" or perf tools, originally "Performance Counters for Linux", PCL) is a performance analyzing tool in Linux, available from Linux kernel version 2.6.31. Userspace controlling utility, named perf, is accessed from the command line and provides a number of subcommands; it is capable of statistical profiling of the entire system (both kernel and userland code).It supports hardware performance counters, tracepoints, software performance counters (e.g.