Performance Measurement on Heterogeneous Processors with PAPI

Modern computer processors improve their computing power by having multiple cores. Traditionally these cores were homogeneous: many identical cores with the same capabilities. Instead it is possible to create processors that have heterogeneous (or hybrid) cores, where the various cores have differing capabilities. This can lead to energy savings and other efficiencies, but complicates performance analysis. Heterogeneous cores have been common for years in embedded ARM processors; recently support has appeared in x86 desktop processors as well. It is likely that before long server and high-performance systems will also gain hybrid cores.We look at current Linux support for heterogeneous processors and detail the various problems encountered when adding support for them to the PAPI performance measurement library.