Symbiotic jobscheduling with priorities for a simultaneous multithreading processor

Abstract

Simultaneous Multithreading machines benefit from jobscheduling software that monitors how well coscheduled jobs share CPU resources, and coschedules jobs that interact well to make more efficient use of those resources. As a result, informed coscheduling can yield significant performance gains over naive schedulers. However, prior work on coscheduling focused on equal-priority job mixes, which is an unrealistic assumption for modern operating systems.This paper demonstrates that a scheduler for an SMT machine can both satisfy process priorities and symbiotically schedule low and high priority threads to increase system throughput. Naive priority schedulers dedicate the machine to high priority jobs to meet priority goals, and as a result decrease opportunities for increased performance from multithreading and coscheduling. More informed schedulers, however, can dynamically monitor the progress and resource utilization of jobs on the machine, and dynamically adjust the degree of multithreading to improve performance while still meeting priority goals.Using detailed simulation of an SMT architecture, we introduce and evaluate a series of five software and hardware-assisted priority schedulers. Overall, our results indicate that coscheduling priority jobs can significantly increase system throughput by as much as 40%, and that (1) the benefit depends upon the relative priority of the coscheduled jobs, and (2) more sophisticated schedulers are more effective when the differences in priorities are greatest. We show that our priority schedulers can decrease average turnaround times for a random jobmix by as much as 33%.

Cross-architecture prediction based scheduling for energy efficient execution on single-ISA heterogeneous chip-multiprocessors

“…The SOS scheduler is originally proposed for the simultaneous multi-threading execution [32]. Many heterogeneous scheduling algorithms presented in prior works also fall into this category [5,17].…”

Managing Data Placement in Memory Systems with Multiple Memory Controllers

“…While the problem formulations are similar to our work, the constraints of memory controller scheduling are different. Snavely et al [55] schedule tasks from a pending task queue on to a number of available thread contexts in an SMT processor. Zhou et al [66] schedule tasks on a 3D processor in an attempt to minimize thermal emergencies.…”

Simulation and Performance Analysis of Multi-core Thread Scheduling and Migration Algorithms

“…Sampling-based scheduling algorithms periodically sample some performance event counter which are monitored such as IPC and cache misses, e.g. [8,9]. Symbiotic scheduling [9] sampled various job combinations and recorded performance metrics for each job combination.…”

“…[8,9]. Symbiotic scheduling [9] sampled various job combinations and recorded performance metrics for each job combination. Symbiosis refers to the group of threads which can run together with the minimal interference thus hurting each other's performance the least.…”