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3.5.2. OProfile 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, such as when memory is referenced, the number of L2 cache requests, and the number of hardware interrupts received. It can also be used to determine processor usage, and which applications and services are used most. OProfile can also be used with Eclipse via the Eclipse OProfile plug-in. This plug-in allows users to easily determine the most time-consuming areas of their code, and perform all command-line functions of OProfile with rich visualization of the results. However, users should be aware of several OProfile limitations: Performance monitoring samples may not be precise - because the processor may execute instructions out of order, a sample may be recorded from a nearby instruction, instead of the instruction that triggered the interrupt. Because OProfile is system-wide and expects processes to start and stop multiple times, samples from multiple runs are allowed to accumulate. This means you may need to clear sample data from previous runs. It focuses on identifying problems with CPU-limited processes, and therefore does not identify processes that are sleeping while they wait on locks for other events. For further information about using OProfile, refer to the Deployment Guide, available fromhttp://access.redhat.com/knowledge/docs/Red_Hat_Enterprise_Linux/, or to the oprofiledocumentation on your system, located in /usr/share/doc/oprofile-.

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