What is Parallel Aware Scheduling?
Parallel Aware Scheduling is an operating system scheduling strategy that utilizes a more global view of process scheduling than that of a single node. This is especially important for large node count parallel applications. As the interactions among cooperating processes increase, mechanisms to ameliorate waiting within one or more of the processes become more important. In particular, collective operations such as barriers and reductions are extremely sensitive to even usually harmless events such as context switches among members of the process working set. The objective is for all the tasks to have the same priority across all processors, and to force other system activity into periodic and aligned time slots during which the MPI tasks do not actively compete for CPU resources. In this way, the effects of operating system interference are reduced for synchronous collective calls (e.g. MPI_Allreduce, MPI_Barrier, MPI_Allgather, …). The below figure depicts two schedulings of the s
