Migration policies for multi-core fair-share scheduling

Abstract

In this paper, we describe an extension of the Linux kernel scheduler called the Practical Fair-Share Scheduler (PFS). PFS is a fair-share process scheduler designed to support real-time workloads with soft (i.e., elastic) timeliness requirements. Fair-share scheduling is a common choice for soft real-time systems since it is work conserving and ensures a minimum CPU allocation for each process. A novel aspect of PFS is its treatment of placement and migration in SMP or multi-core settings. Other fair-share schedulers have used ad hoc policies for handling these issues, often leading to underutilization and increased system lag. In contrast, PFS uses a strategy that maintains utilization without unfairly penalizing processes. We spend the remainder of this paper discussing placement and migration. A more extensive description of PFS, including source code, can be found at the download site listed in the citations.