Towards a Performance Tool Interface for OpenMP: An Approach Based on Directive Rewriting

In this article we propose a “standard” performance tool interface for OpenMP, similar in spirit to the MPI profiling interface in its intent to define a clear and portable API that makes OpenMP execution events visible to performance libraries. When used together with the MPI profiling interface, it also allows tools to be built for hybrid applications that mix shared and distributed memory programming. We describe an instrumentation approach based on OpenMP directive rewriting that generates calls to the interface and passes context information (e.g., source code locations) in a portable and efficient way. Our proposed OpenMP performance API further allows user functions and arbitrary code regions to be marked and performance measurement to be controlled using new proposed OpenMP directives. The directive transformations we define are implemented in a source-tosource translation tool called Opari. We have used it to integrate the Tau performance analysis framework [13] and the automatic event trace analyzer expert [17, 18] with the proposed OpenMP performance interface. Together, these tools show that a portable and robust solution to performance analysis of OpenMP and hybrid applications is possible.