Tutorial: Identifying bottleneck in applications
Joint Laboratory for Petascale Computing Workshop (JLPC) 2014
Publication Type: Talk
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Topic: HPC Applications Performance Analysis and Debugging Speaker Sanjay Kale (Professor in the CS dept., University of Illinois, Urbana Champaign) and Ronak Buch (PhD candidate, University of Illinois, Urbana Champaign) Slides 1_charmIntroShort.pdf 1_charmIntroShort.pptx 2_Projections_Overview.pdf 2_Projections_Overview.pptx 3_Case_Studies_with_Projections.pdf 3_Case_Studies_with_Projections.pptx Videos Unavailable at the moment. I'm working on it… Context Performance of parallel applications is notoriously hard to optimize. This gets even more challenging when running a large number of processors, and/or during strong scaling of an application to the limit of its scaling. Fortunately, one can obtain detailed performance data in the form of traces or summaries. However, it requires skill and expertise to use this data to identify the major bottleneck that is holding up performance. This is further compounded by the "whack a mole" nature of performance debugging: when you fix one problem, another problem that was masked by the first one emerges as the next bottleneck. Program In this tutorial, we will learn about techniques and methodologies that one can use to hold onto and saw that the major performance problems faced by your applications. You will learn about different views of performance, such as time profiles, processor profiles, communication graphs, outlier analysis, histograms, and the richest of them all: detailed timelines. You will then learn about the rules, heuristics, and idioms (i.e. sequence of analysis/visualizations in pursuit of a conclusion or inference) that experts use in performance tuning. The tutorial will use the projections performance analysis tool that is part of the Charm++ parallel programming system. It will include several case studies from applications such as NAMD (biophysics), ChaNGa (astronomy), and several mini-applications. Prerequisites It is required that the attendees download and test "Projections" on their laptops. In addition, several log files will be provided that must be downloaded prior to the workshop. Projections can be downloaded from http://charm.cs.uiuc.edu/software
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