Task-Based Cholesky Decomposition on Knights Corner Using OpenMP

The growing popularity of the Intel Xeon Phi coprocessors and the continued development of this new many-core architecture have created the need for an open-source, scalable, and cross-platform task-based dense linear algebra package that can efficiently use this type of hardware. In this paper, we examined the design modifications necessary when porting PLASMA, a task-based dense linear algebra library, to run effectively on Intel’s Knights Corner Xeon Phi coprocessor. First, we modified PLASMA’s tiled Cholesky decomposition to use OpenMP for its scheduling mechanism to enable Xeon Phi compatibility. We then compared the performance of our modified code to that of the original dynamic scheduler running on an Intel Xeon Sandy Bridge CPU. Finally, we looked at the performance of the new OpenMP tiled Cholesky decomposition on a Knights Corner coprocessor. We found that desirable performance for this architecture was attainable with the right code optimizations; these changes were necessary to account for differences in the runtimes and in the hardware itself.