Nuclear Meltdown? Assessing the impact of the Meltdown/Spectre bug at Los Alamos National Laboratory LA-UR-18-24290

With the recent revelation of the Meltdown/Spectre bug, much speculation has been levied on the performance impact of the fixes to avoid potential compromises. Single node, single process codes have had very high impact estimates, but little is known on the extent to which the early patches will affect large-scale MPI jobs. Will the delays cascade into jitter vapor lock, or will the delays get lost in the waves on the ocean? Or is reality somewhere in the middle? With flagship codes and their performance driving future systems design and purchase, it is important to understand the new normal. In an investigative assessment, we research how the updates affect job performance of various benchmark codes as well as our mainstay workloads across different job sizes and architectures. Keywords-Meltdown; Spectre; LANL;