Friday, October 30, 2015

SC15 Invited Talk-Dr. Laura Grigori Presents Fast and Robust Communication Avoiding Algorithms: Current Status and Future Prospects

Left: computation to communication ratio for the LU factorization with partial pivoting of a dense matrix on a model of exascale machine (ISC 2014). Right: preconditioned Krylov solver as used in the map making problem in astrophysics, results obtained on a Cray XE6 machine (Astronomy and Astrophysics, 2014). Please click to enlarge.
This talk will address one of the main challenges in high performance computing which is the increased cost of communication with respect to computation, where communication refers to data transferred either between processors or between different levels of memory hierarchy, including possibly NVMs.

I will overview novel communication avoiding numerical methods and algorithms that reduce the communication to a minimum for operations that are at the heart of many calculations, in particular numerical linear algebra algorithms.

Communication avoiding LU uses tournament pivoting to minimize communication (SC08).  Lightweight scheduling combines static and dynamic scheduling to provide a good trade-off beween load balance, data locality and dequeue overhead (IPDPS 2012). Please click to enlarge.
Those algorithms range from iterative methods as used in numerical simulations to low rank matrix approximations as used in data analytics. I will also discuss the algorithm/architecture matching of those algorithms and their integration in several applications.

Speaker Background:
Dr. Laura Grigori
Dr. Laura Grigori obtained her Ph.D. in Computer Science in 2001 from University Henri Poincare in France. She was a postdoctoral researcher at UC Berkeley and Lawrence Berkeley National Laboratory, before joining French Institute for Research in Computer Science and Automation (INRIA) in France in 2004.

Currently she now leads a joint research group between INRIA, University of Pierre and Marie Curie, and the National Center for Scientific Research (CNRS), called Alpines.

Her field of expertise is high performance scientific computing, numerical linear algebra, and combinatorial scientific computing. She co-authored the papers introducing communication avoiding algorithms that provably minimize communication.

She is leading several projects in preconditioning, communication avoiding algorithms, and associated numerical libraries for large scale parallel machines. She is currently the Program Director of the SIAM Special Interest Group on Supercomputing.

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