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2.12. OProfile
OProfile is a system-wide performance monitoring tool. It uses the processor's dedicated performance monitoring hardware to retrieve information about the kernel and system executables to determine the frequency of certain events, such as when memory is referenced, the number of second-level cache requests, and the number of hardware requests received. OProfile can also be used to determine processor usage, and to determine which applications and services are used most often.
However, OProfile does have several limitations:
- Performance monitoring samples may not be precise. Because the processor may execute instructions out of order, samples can be recorded from a nearby instruction instead of the instruction that triggered the interrupt.
- OProfile expects processes to start and stop multiple times. As such, samples from multiple runs are allowed to accumulate. You may need to clear the sample data from previous runs.
- OProfile focuses on identifying problems with processes limited by CPU access. It is therefore not useful for identifying processes that are sleeping while they wait for locks on other events.
For more detailed information about OProfile, see Section A.14, “OProfile”, or the Red Hat Enterprise Linux 7 System Administrator's Guide. Alternatively, refer to the documentation on your system, located in
/usr/share/doc/oprofile-version.
