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Thursday, March 5 • 15:15 - 17:15
Poster: 'Communication Avoiding Algorithms: Analysis and Code Generation for Parallel Systems,' Karthik Murthy, Rice University

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The computing power of a processor has increased a thousand fold over the last 20 years. As the computing power continues to increase following the predictions of "Moore's law," communication is increasingly becoming the principal power and performance bottleneck. The "ExaScale Computing Study: Technology Challenges in Achieving Exascale Systems" opines that it is easier to solve the power problem for intra-node computation than it is to solve the problem of inter-processor communication. The class of communication-avoiding .5D algorithms were developed to address the problem of inter-processor communication. These algorithms reduce communication and provide strong scaling in both time and energy. As a first step towards automating the development of communication-avoiding libraries, we developed the Maunam compiler.  Maunam generates efficient parallel code from a high level, global view sketch of .5D algorithms that are expressed using symbolic data sizes and numbers of processors. It supports the expression of data movement and communication through high-level global operations such as TILT and CSHIFT as well as through element-wise copy operations. Wrap-around communication patterns can also be achieved using subscripts based on modulo operations.  Maunam employs polyhedral analysis to reason about the communication and computation present in the input .5D algorithm. It partitions data and computation then inserts point-to-point and collective communication as needed. Maunam also analyzes data dependence patterns and data layouts to identify reductions over processor subsets.  Maunam-generated Fortran+MPI code for 2.5D matrix multiplication running on 4096 cores of a Cray XC30 supercomputer achieves 59 TFlops/s (76% of the machine peak).

Speakers

Thursday March 5, 2015 15:15 - 17:15 CST
BioScience Research Collaborative 6500 Main Street, Houston, Tx 77005

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