Reduction of operating system jitter caused by page reclaim

Abstract

Operating system jitter is one of the major causes of runtime overhead in applications of high performance computing. Jitter results from the execution of services by the operating system kernel, such as interrupt handling and tasklets, or the execution of various daemon processes developed in order to provide operating system services, such as memory management daemons. This execution interrupts application computations and increases their execution time. Jitter significantly affects applications where many processes or threads frequently synchronize with each other. In this paper, we investigate the impact of jitter caused by reclaiming memory pages, and propose a method for reducing the impact. The target operating system is Linux. When the Linux kernel runs out of memory, the kernel awakens a special kernel thread to reclaim memory pages that are unlikely to be used in the near future. If the kernel thread is frequently awakened, application performance is degraded because of its resource consumption. The proposed method can reclaim memory pages in advance of the kernel thread. It reclaims more pages at one time than the kernel thread, thus reducing the frequency of page reclaim and the impact of jitter. We implement a system based on the proposed method and conduct an experiment using practical weather forecast software. Results of the experiment show that the proposed method minimizes performance degradation caused by jitter.