The PAPI Cross-Platform Interface to Hardware Performance Counters

The purpose of the PAPI project is to specify a standard API for accessing hardware performance counters available on most modern microprocessors. These counters exist as a small set of registers that count "events", which are occurrences of specific signals and states related to the processor's function. Monitoring these events facilitates correlation between the structure of source/object code and the efficiency of the mapping of that code to the underlying architecture. This correlation has a variety of uses in performance analysis and tuning. The PAPI project has developed a standard set of hardware events and a standard cross-platform library interface to the underlying counter hardware. The PAPI library has been implemented for a number of Shared Resource Center platforms. The PAPI project is developing end-user tools for dynamically selecting and displaying hardware counter performance data. PAPI support is also being incorporated into a number of third-party tools.