msr-genie: Navigating Model Specific Registers Across Processor Generations.

Performance tuning of High-Performance Computing (HPC) applications depends on sophisticated tuning of parameters on diverse architectures. These parameters are made available by vendors through low-level dials such as model-specific registers (MSRs). While the MSRs themselves provide a powerful mechanism for users to monitor and control processor features, accessing them is laborious due to lack of standard interfaces and clear documentation. As a result, the burden of determining which MSRs to consider and how to fine-tune them for an application lies with the end user. In this paper, we present msr-genie, an efficient and extensible query tool that reduces this user-level burden. The tool allows them to query bi-directionally across MSR lists as well as processor families and models, and provides them with guidance on appropriate bitmasks. The msr-genie tool is open-source and easily extensible, and we demonstrate its effectiveness with over thirty Intel processor models and over two-thousand unique MSRs.