Hill-Climbing SMT Processor Resource Scheduler

نویسندگان

  • Seungryul Choi
  • Donald Yeung
چکیده

Multiple threads in SMT processor share resources to increase resource utilization and improve overall performance. At the same time, they compete against each other for the shared resources, causing resource monopolization or underutilization. Therefore, resource scheduling mechanism is important because it determines the throughput as well as fairness of the simultaneously running threads in SMT processor. To achieve optimal SMT performance, all the earlier mechanisms schedule resources based on a couple of indicators, such as cache miss count, predecoded instruction count, or resource demand/occupancy. Those indicators trigger scheduling actions, expecting improved performance. However, since combinations of indicators can not cover all possible cases of threads behavior, earlier mechanisms may face a situation where the expected positive correlation between the indicators and the performance becomes weak, losing the chance of performance improvement. In this paper, we developed a novel methodology using hill-climbing or gradient descent algorithm to find the optimal resource share of simultaneously running threads. We carefully vary the resource share of multiple threads toward the direction which improves the SMT performance. Instead of monitoring the behavior of indicators, we use the past resource share and SMT performance change history to determine the resource share shift direction for the future. Simulation result shows that our hill-climbing resource scheduler outperforms FLUSH by 5.0% and DCRA by 1.4%, on average, using the weighted IPC as a metric.

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تاریخ انتشار 2005