Optimising sparse matrix-vector products at EPCC

Author: Guest blogger
Posted: 15 Aug 2019 | 11:35

Edoardo Coronado visited EPCC from 18th May–15th August 2019 under the HPC-Europa3 programme. 

Hi! My name is Edoardo Coronado. I am a Mexican PhD student in Technologies of Information at the "Centro Singular de Investigación en Tecnoloxías Intelixentes" (CiTIUS) at the "Universidad de Santiago de Compostela" in Spain. I work on the optimisation of iterative solvers on accelerator devices. I have spent three months at EPCC at the University of Edinburgh under the HPC-Europa3 transnational access programme with Mr Adrian Jackson acting as my host.

I work on the optimisation of iterative solvers by improving the performance of key operations such as sparse matrix-vector (SpMV) products on Intel Xeon Phi coprocessors (Knights Corner) by implementing a new sparse matrix storage format called AXC that exploits the cache utilisation of this coprocessor. Improving this operation impacts directly on the iterative solver’s performance, and consequently on all numerical software that uses it as a part of an algorithm to generate solutions (eg numerical simulators).

During my visit to EPCC I focused on optimising the AXC format, specifically working on:

  • Solving the load imbalance between threads due to the design of the format.
  • Reducing its memory footprint.
  • Expanding its utilisation to NVIDIA GPUs.

My HPC-Europa fellowship allowed me access to EPCC's Cirrus server, which has a partition of GPU nodes. Each node on this partition has two Intel Xeon Gold processors and four NVIDIA V100 GPUs (Volta architecture). As a consequence, I have been programming in CUDA to target the GPUs and also using the Intel AVX-512 instructions to exploit the Intel Xeon Gold processors usage. I also had access to and used ICHEC’s Kay server, which has 16 nodes with two Intel Xeon Gold processors, with two NVIDIA V100 GPUs per node. This work has fixed the aforementioned issues and has successfully broadened the usage area of the format to a new platform.  

In my free time I have enjoyed Edinburgh with my family. We have spent afternoons in the Meadows (a green park area in the centre of Edinburgh), and visited other parks as well as monuments and historic buildings in Edinburgh and other parts of Scotland. We had the opportunity to attend a performance of the Military Tattoo on the Edinburgh Castle Esplanade, which we really enjoyed.

Ms Catherine Inglis (EPCC) provided me with not only excellent administrative support, but with invaluable help to stay in the city and finish my visit successfully.

Dr Mario Antonioletti (EPCC) made my access to Cirrus an effortless procedure, helped me with any platform-related issues, provided me with hardware when mine was failing and gave me professional advice that helped me to perform the visit-related tasks more efficiently. 

I strongly recommend applying to the HPC-Europa3 programme, especially to visit Edinburgh. You will find a city of contrasts where you can see modern architectures merging perfectly with ancient buildings, cold weather, and warm people.

HPC-Europa3 website: www.hpc-europa.eu/

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