system-wide profiler for Linux systems OProfile is a performance profiling tool for Linux systems, capable of profiling all running code at low overhead. It consists of a daemon for collecting sample data, plus several post-profiling tools for turning data into information. Using OProfile also requires a kernel module, either contained in a separate package called 'oprofile-modules' for 2.2 and 2.4 kernels, or for 2.6 kernels, the OProfile kernel module is part of the Linux kernel source and must be built from the 'kernel-source' package. OProfile leverages the hardware performance counters of the x86 CPU and the PMU (Performance Monitoring Unit) of the ia64 CPU to enable profiling of a wide variety of interesting statistics, which can also be used for basic time-spent profiling. All code is profiled: hardware and software interrupt handlers, kernel modules, the kernel, shared libraries, and applications (the only exception being the OProfile interrupt handler itself). Note that different architectures can use different hardware mechanisms to collect data. OProfile is currently in alpha status; however it has proven stable over a large number of differing configurations. As always, there is no warranty.