FlexDCP: a QoS framework for CMP architectures

摘要

Current multicore architectures offer high throughput by increasing hardware resource utilization. As the number of cores in a multi-core system increases, providing Quality of Service (QoS) to applications in addition to throughput is becoming an important problem. In this work, we present FlexDCP, a framework that allows the Operating System (OS) to guarantee a QoS for each application running in a chip multiprocessor. FlexDCP directly estimates the performance of applications for different cache configurations instead of using indirect measures of performance like the number of misses. This information allows the OS to convert QoS requirements into resource assignments. Consequently, it offers more flexibility to the OS as it can optimize different QoS metrics like per-application performance or global performance metrics such as fairness, weighted speed up or throughput. Our results show that FlexDCP is able to force applications in a workload to run at a certain percentage of their maximum performance in 94% of the cases considered, being on average 1.48% under the objective for remaining cases. When optimizing a global QoS metric like fairness, FlexDCP consistently outperforms traditional eviction policies like LRU, pseudo LRU and previous dynamic cache partitioning proposals for two-, four- and eight-core configurations. In an eight-core architecture FlexDCP obtains a fairness improvement of 10.1% over Fair, the best policy in the literature optimizing fairness.