PHLAME: Hierarchical Locality Exploitation Using the PGAS Model

Parallel computers are becoming deeply hierarchical. Locality aware programming models allow programmers to control locality at one level through establishing affinity between data and executing activities. This, however, does not enable locality exploitation at other levels. Therefore, we must conceive an efficient abstraction of hierarchical locality and develop techniques to exploit it. Techniques applied directly by programmers, beyond the first level, burden the programmer and hinder productivity. In this work, we propose the Parallel Hierarchical Locality Abstraction Model for Execution (PHLAME). PHLAME is an execution model to abstract and exploit machine hierarchical properties through locality-aware programming and a runtime system that takes into account machine characteristics, data sharing and communication profile of the underlying application. This paper presents and experiments with concepts and techniques that can drive such runtime system in support of PHLAME. Our experiments show that our techniques scale to 1024 cores and achieve performance gains of up to 88%.