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Visualization Tool for Development of Communication Algorithms and a Case Study Using the K Computer

Authors:
Syunji Yazaki
Ryohei Suzuki
Fumiyoshi Shoji
Kenichi Miura
Hiroaki Ishihata

Keywords: Visualization, Mesh/Torus network, All-to-all

Abstract:
In this paper, we introduce our visualization tool, the Communication Log Viewer (CLV), that assists the development of collective communication algorithms. We also present visualization results as a case study. CLV visualizes information regarding node events and network statistics in linked multiple views. CLV also has a function for analyzing the results obtained from network simulators and actual machines in the same framework, which is useful when developers repeatedly test their algorithms on a simulator and an actual system. For a case study, we visually evaluated two all-to-all algorithms on the full system of the K computer that has 82,944 nodes. As a result, we confirmed that an optimized all-to-all algorithm implemented for the K computer performed better than an all-to-all implemented in Open MPI. We also confirmed that the barrier operation used in the K computer’s Message Passing Interface (MPI) functions keep link utilization high. However, there is also a trade-off between the number of barriers and link utilization.

Pages: 54 to 59

Copyright: Copyright (c) IARIA, 2015

Publication date: March 22, 2015

Published in: conference

ISSN: 2308-3735

ISBN: 978-1-61208-389-6

Location: Nice, France

Dates: from March 22, 2015 to March 27, 2015