Colloquium 2024 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.