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Friday, September 29 • 1:30pm - 2:30pm
The Point of Views: Multidimensional Index Sets for Data Locality in HPC Applications

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In High Performance Computing, the commonly used concepts to formulate data access are fundamentally different from those provided by the STL. In this session, you will learn why programming abstractions for distributed container elements indeed need additional expressiveness and how modern C++ allows to achieve it.

Even for a seemingly trivial array there are countless ways to partition and store its elements in distributed memory, and algorithms are required to behave and scale identically for all of them. It also does not help that most applications operate on multidimensional data structures where efficient access to neighborhood regions is crucial. Among HPC developers, it is therefore widely accepted that canonical iteration space and physical memory layout must be specified as separate concepts. For this, iterators, even with the proposals for views and ranges, just are not enough.

The DASH C++ template library is an implementation of Partitioned Global Address Space (PGAS), a programming abstraction that presents distributed memory as unified virtual global memory. DASH is designed as a PGAS implementation of the STL and complies with its semantics and constraints. STL algorithms called with global iterators on distributed containers show expected behavior.

When we started to extend DASH by support for heterogeneous systems, it became obvious that the definition, conversion, and combination of iteration spaces asks for a more fundamental, formal approach. For this, we extended the proposed view- and range concepts by multidimensional index sets and achieved an expressive and efficient abstraction for multidimensional data.

avatar for Tobias Fuchs

Tobias Fuchs

Research Associate, LMU Munich, Leibniz Supercomputing Centre
Tobi is a freelancer in embedded systems for over 10 years, especially medical devices, and went back to academia for PhD studies in High Performance Computing at LMU Munich. | He is the lead developer of the DASH C++ template library, a DFG research project, and currently focu... Read More →

Friday September 29, 2017 1:30pm - 2:30pm
Meydenbauer TBA #5 Meydenbauer Center
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