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Technologies such as Multi-Channel DRAM (MCDRAM) or High Bandwidth Memory (HBM) provide significantly more bandwidth than conventional memory. This trend has raised questions about how applications should manage data transfers between levels.This paper focuses on evaluating different usage modes of the MCDRAM in Intel Knights Landing (KNL) manycore processors. We evaluate these usage modes with a sorting kernel and a sortingbased streaming benchmark. We develop a performance model for the benchmark and use experimental evidence to demonstrate the correctness of the model. The model projects near-optimal numbers of copy threads for memory bandwidth bound computations. We demonstrate on KNL up to a 1.9X speedup for sort when the problem does not fit in MCDRAM over an OpenMP GNU sort that does not use MCDRAM.
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Evaluation of Knight Landing High Bandwidth Memory for HPC Workloads
The Intel Knight Landing (KNL) manycore chip includes 3D-stacked memory named MCDRAM, also known as High Bandwidth Memory (HBM) for parallel applications that needs to scale to high thread count. In this paper, we provide a quantitative study of the KNL for HPC proxy applications including Lulesh, HPCG, AMG, and Hotspot when using DDR4 and MCDRAM. The results indicate that HBM significantly improves the performance of memory intensive applications for as many as three times better than DDR4 in HPCG, and Lulesh and HPCG for as many as 40% and 200%. For the selected compute intensive applications, the performance advantage of MCDRAM over DDR4 varies from 2% to 28%. We also observed that the cross-points, where MCDRAM starts outperforming DDR4, are around 8 to 16 threads.
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- Award ID(s):
- 1652732
- PAR ID:
- 10050477
- Date Published:
- Journal Name:
- IA3'17 Proceedings of the Seventh Workshop on Irregular Applications: Architectures and Algorithms
- Page Range / eLocation ID:
- 1 to 4
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1145/3149704.3149766
