Characterizing the caching and synchronization performance of a multiprocessor operating system
Josep Torrellas, Anoop Gupta, John LeRoy Hennessy · 1992
Good cache memory performance is essential to achieving high CPU utilization in shared-memory multiprocessors.While the performance of caches is determined by both application end operating system (OS ) references, most research has focused on the cache performance of applications afone.This is partiafly due to the difficulty of measuring OS activity and as a resrtl~the cache performance of the OS is largely unknown.In this paper, we characterize the cache performance of a commercial System V UNIX rtrttrtittg on a four-CPU multiprocessor.The related issue of the performance impact of the OS synchronization activity is tdso stttdicd.For our study, we use a hardware monitor that records the cache misses in the machine without perturbing it.We study three multiprocessor workloads: a parallel Compilq a multiprogrsmmed load and a commercial database.Our results show that OS misses occur frequently enough to stall CPUS for 17-21 'Yoof their non-idle time.Further, if we include application misses induced by OS interference in the cache, then the SQU time reaches 25%.A detailed analysis reveals three major sources of OS misses: instruction fetehea, process migratiom and data accesses in block operations.As for synchronization behavior, we find that OS syncfrrordzation has low overhead if supported correctly end that OS locks show good locality and low contention.