False Sharing and Contention in Parallel Codes

Sequential programs can repeatedly read from and write to memory locations seemingly without issues. On the other hand, parallel programs can easily fall prey to weird behaviours resulting in small to very significant issues and/or performance loss that are not always easily attributable to specific pieces of code one has written. Such behaviours can be seen in multithreaded C, C++, Fortran, OpenMP, etc. parallel codes running on shared memory systems. This presentation will discuss false sharing and contention, the issues resulting from them, and how one can address such so as to minimize if not eliminate their negative effects.
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This webinar was presented by Paul Preney (SHARCNET) on January 17th, 2024, as a part of a series of weekly Compute Ontario Colloquia. The webinar was hosted by SHARCNET. The colloquia cover different advanced research computing (ARC) and high performance computing (HPC) topics, are approximately 45 minutes in length, and are delivered by experts in the relevant fields. Further details can be found on this web page: www.computeont... . Recordings, slides, and other materials can be found here: helpwiki.sharc...
SHARCNET is a consortium of 19 Canadian academic institutions who share a network of high performance computers (www.sharcnet.ca). SHARCNET is a part of Compute Ontario (computeontario.ca/) and Digital Research Alliance of Canada (alliancecan.ca).