Posts by George Markomanolis

Affinity part 2 - System topology and controlling affinity

In Part 1 of the Affinity blog series, we looked at the importance of setting affinity for High Performance Computing (HPC) workloads. In this blog post, our goals are the following:

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Affinity part 1 - Affinity, placement, and order

Modern hardware architectures are increasingly complex with multiple sockets, many cores in each Central Processing Unit (CPU), Graphical Processing Units (GPUs), memory controllers, Network Interface Cards (NICs), etc. Peripherals such as GPUs or memory controllers will often be local to a CPU socket. Such designs present interesting challenges in optimizing memory access times, data transfer times, etc. Depending on how the system is built, hardware components are connected, and the workload being run, it may be advantageous to use the resources of the system in a specific way. In this article, we will discuss the role of affinity, placement, and order in improving performance for High Performance Computing (HPC) workloads. A short case study is also presented to familiarize you with performance considerations on a node in the Frontier supercomputer. In a follow-up article, we also aim to equip you with the tools you need to understand your system’s hardware topology and set up affinity for your application accordingly.

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