参加者の感想 ― 並列プログラミングチャレンジ （Parallel Programming Challenge）のGold Winner

Comments on winning the 3rd Annual IHPCSS Challenge
ZHANG Jiachao

Gold Winner のZhangさん（右）と本スクールの実行委員である機構の今村チームリーダー

During this summer school, the 3rd Annual IHPCSS Challenge program was held, and I was fortunate to win the award this time.

The challenge program involves performing hybrid parallelism, using MPI plus OpenMP or OpenACC, to speed up a typical Laplace Solver program under the limitation of assigned nodes. I worked as a team with Stefan Hofmeister, a friend from Germany who I met at this summer school. Since there are four nodes available and each node equips with two GPUs, we decided to use MPI and OpenACC to accelerate this program. The efforts included utilizing all eight GPUs via OpenACC compiled by PGI compiler; utilizing the pgi_mvapich library, which perhaps supports more advanced interconnection; utilizing overlapping of communication and computing and some revision in MPI. Finally, the performance was around 6.5 seconds in the challenge and this result was enough to win the championship.

Through this challenge, I benefited a lot. Firstly, it enabled me to understand the meaning of general-purpose acceleration, which is applicable to various applications in other fields. It encouraged me to focus on strengthening my foundation knowledge in computer science, as I hope to devote more time to HPC projects in future. Secondly, I experienced using batch processing to debug programs in a supercomputer. By experiencing the advantages and disadvantages of batch processing, I can gain a better understanding of my own research, interactive simulation systems, which assume computing resource is used in real-time. Thirdly, it reminded me to expect the unexpected and of the importance of team work. I realized it’s often necessary to just try and don’t give up. Although free time is very limited for this challenge in summer school, spend a bit more time because it’s possible to optimize a little more for the purpose of studying.

I really appreciate the precious opportunity to attend this summer school supported by RIKEN, JAPAN. I learned a lot from the presentations, lectures, mentoring and other activities. And the most important part is that I had the chance to talk with many experienced professors and talented young friends. The things I learned will last with me for a long time and will encourage me to try my best to study and work in HPC in the future.