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Publications of SPCL
|T. Hoefler, T. Schneider and A. Lumsdaine:|
|Accurately Measuring Collective Operations at Massive Scale|
(. Vol , Nr. , In Proceedings of the 22nd IEEE International Parallel & Distributed Processing Symposium, PMEO'08 Workshop, presented in Miami, FL, pages , , ISSN: 1530-2075, ISBN: 978-1-4244-1694-3, Apr. 2008)
Invited to a journal special issue on top picks from PMEO'08.
AbstractAccurate, reproducible and comparable measurement of collective operations is a complicated task. Although Different measurement schemes are implemented in well-known benchmarks, many of these schemes introduce different systematic errors in their measurements. We characterize these errors and select a window-based approach as the most accurate method. However, this approach complicates measurements significantly and introduces a clock synchronization as a new source of systematic errors. We analyze approaches to avoid or correct those errors and develop a scalable synchronization scheme to conduct benchmarks on massively parallel systems. Our results are compared to the window-based scheme implemented in the SKaMPI benchmarks and show a reduction of the synchronization overhead by a factor of 16 on 128 processes.