PAPI2

PAPI2 is the second major release within the Performance API (PAPI) project, an open-source, portable library designed to provide a uniform interface to hardware performance counters across a range of processors and systems. It aims to simplify the collection of low-level performance data for profiling, benchmarking, and research by masking architecture-specific details behind a stable API.

The PAPI2 API typically offers a C interface with language bindings and a framework that can adapt to different architectures and operating systems. Core capabilities include discovering available performance events, creating and managing event sets, starting and stopping counters, and reading or accumulating results. It also supports multiplexing when the number of requested events exceeds the available counters, and provides multi-threaded and multi-process contexts for collaborative or concurrent profiling. In addition, PAPI2 often includes wrappers for Fortran and other languages to extend its usability in various environments.

Usage generally involves initializing the library, querying or selecting events relevant to the target hardware, configuring event sets, and then starting, stopping, and reading counters to obtain measurements. The API abstracts many hardware specifics, mapping high-level events to the underlying performance monitoring units (PMUs) of the host system, thereby enabling consistent data collection across platforms.

PAPI2 is distributed as part of the open-source PAPI project under a permissive license. Availability, platform support, and the exact set of features can vary by operating system, compiler, and hardware. Users are advised to consult the official PAPI documentation and repositories for current guidance, examples, and compatibility notes.