Investigating Operating System Noise in Extreme-scale High-performance Computing Systems Using Simulation

Hardware/software co-design for future-generation highperformance computing (HPC) systems aims at closing the gap between the peak capabilities of the hardware and the performance realized by applications (applicationarchitecture performance gap). Performance profiling of architectures and applications is a crucial part of this iterative process. The work in this paper focuses on operating system (OS) noise as an additional factor to be considered for co-design. It represents the first step in including OS noise in HPC hardware/software co-design by adding a noise injection feature to an existing simulation-based co-design toolkit. It reuses an existing abstraction for OS noise with frequency (periodic recurrence) and period (duration of each occurrence) to enhance the processor model of the Extreme-scale Simulator (xSim) with synchronized and random OS noise simulation. The results demonstrate this capability by evaluating the impact of OS noise on MPI Bcast() and MPI Reduce() in a simulated futuregeneration HPC system with 2,097,152 compute nodes.