A64FX – Your Compiler You Must Decide! (FY2021)

The current number one of the TOP500 list, Supercomputer Fugaku, has demonstrated that CPU-only HPC systems aren’t dead and CPUs can be used for more than just being the host controller for a discrete accelerators. While the specifications of the chip and overall system architecture, and benchmarks submitted to various lists, like TOP500 and Green500, etc., are clearly highlighting the potential, the proliferation of Arm into the HPC business is rather recent and hence the software stack might not be fully matured and tuned, yet. We test three state-of-the-art compiler suite against a broad set of benchmarks. Our measurements show that orders of magnitudes in performance can be gained by deviating from the recommended usage model (i.e., 4 MPI ranks with 12 OpenMP threads each) and recommended compiler for the A64FX compute nodes. Furthermore, our work shows that there is currently no “silver bullet” compiler for A64FX, and hence the operations team of Fugaku added an official LLVM installation based on our findings.

Related Publication

• J. Domke, “A64FX – Your Compiler You Must Decide!,” in Proceedings of the 2021 IEEE International Conference on Cluster Computing (CLUSTER), EAHPC Workshop, (Portland, Oregon, USA), IEEE Computer Society, Sept. 2021.

Matrix Engines for High Performance Computing: A Paragon of Performance or Grasping at Straws? (FY2021)

Matrix engines or units, in different forms and affinities, are becoming a reality in modern processors; CPUs and otherwise. The current and dominant algorithmic approach to Deep Learning merits the commercial investments in these units, and deduced from the No. 1 benchmark in supercomputing, namely High Performance Linpack, one would expect an awakened enthusiasm by the HPC community, too. Hence, our goal was to identify the practical added benefits for HPC and machine learning applications by having access to matrix engines. For this purpose, we performed an in-depth survey of software stacks, proxy applications and benchmarks, and historical batch job records. We provided a cost-benefit analysis of matrix engines, both asymptotically and in conjunction with
state-of-the-art processors. While our empirical data will temper the enthusiasm, we also outline opportunities to “misuse” these dense matrix-multiplication engines if they come for free in future CPU or GPU architectures.

Related Publication

• J. Domke, E. Vatai, A. Drozd, P. Chen, Y. Oyama, L. Zhang, S. Salaria, D. Mukunoki, A. Podobas, M. Wahib, S. Matsuoka, “Matrix Engines for High Performance Computing: A Paragon of Performance or Grasping at Straws?,” in Proceedings of the 35th IEEE International Parallel & Distributed Processing Symposium (IPDPS), (Portland, Oregon, USA), IEEE Computer Society, May 2021.

Compression of Time Evolutionary Image Data through Predictive Deep Neural Networks (FY2021)

Recent advances in Deep Neural Networks (DNNs) have demonstrated a promising potential in predicting the temporal and spatial proximity of time evolutionary data. In this paper, we have developed an effective (de)compression framework called TEZIP that can support dynamic lossy and lossless compression of time evolutionary image frames with high compression ratio and speed. TEZIP first trains a Recurrent Neural Network called PredNet to predict future image frames based on base frames, and then derives the resulting differences between the predicted frames and the actual frames as more compressible delta frames. Next we equip TEZIP with techniques that can exploit spatial locality for the encoding of delta frames and apply lossless compressors on the resulting frames. Furthermore, we introduce window-based prediction algorithms and dynamically pinpoint the trade-off between the window size and the relative errors of predicted frames. Finally, we have conducted an extensive set of tests to evaluate TEZIP. Our experimental results show that, in terms of compression ratio, TEZIP outperforms existing lossless compressors such as x265 by up to 3.2x and lossy compressors such as SZ by up to 3.3x.

Publications:

• Rupak Roy, Kento Sato, Subhadeep Bhattacharya, Xingang Fang, Yasumasa Joti, Takaki Hatsui, Toshiyuki Hiraki, Jian Guo and Weikuan Yu, “Compression of Time Evolutionary Image Data through Predictive Deep Neural Networks”, In the proceedings of the 21 IEEE/ACM International Symposium on Cluster, Cloud and Internet Computing (CCGrid 2021), May, 2021
• Rupak Roy, Kento Sato, Jian Guo, Jens Domke and Weikuan Yu, “Improving Data Compression with Deep Predictive Neural Network for Time Evolutional Data”, In Proceedings of the International Conference on High Performance Computing, Networking, Storage and Analysis 2019 (SC19), Regular Poster, Denver, USA, Nov, 2019.

Optimizing Asynchronous Multi-Level Checkpoint/Restart Configurations with Machine Learning (FY2020)

With the emergence of versatile storage systems, multi-level checkpointing (MLC) has become a common approach to gain efficiency. However, multi-level checkpoint/restart can cause enormous I/O traffic on HPC systems. To use multilevel checkpointing efficiently, it is important to optimize check-point/restart configurations. Current approaches, namely modeling and simulation, are either inaccurate or slow in determining the optimal configuration for a large scale system. In this paper, we show that machine learning models can be used in combination with accurate simulation to determine the optimal checkpoint configurations. We also demonstrate that more advanced techniques such as neural networks can further improve the performance in optimizing checkpoint configurations.

Publications:

• Tonmoy Dey, Kento Sato, Bogdan Nicolae, Jian Guo, Jens Domke, Weikuan Yu, Franck Cappello, and Kathryn Mohror. “Optimizing Asynchronous Multi-Level Checkpoint/Restart Configurations with Machine Learning.” The IEEE International Workshop on High-Performance Storage, May, 2020
• Tonmoy Dey, Kento Sato, Jian Guo, Bogdan Nicolae, Jens Domke, Weikuan Yu, Franck Cappello and Kathryn Mohror, “Optimizing Asynchronous Multi-level Checkpoint/Restart Configurations with Machine Learning”, In Proceedings of the International Conference on High Performance Computing, Networking, Storage and Analysis 2019 (SC19), Regular Poster, Denver, USA, Nov, 2019.