Analysis of False Cache Line Sharing Effects on Multicore CPUs

摘要

False Sharing (FS) is a notorious problem occurring in multiprocessor systems. It results in a performance degradation for multi-threaded programs. Since the architecture of a multicore processor is very similar to that of a multiprocessor system, the presence of the false sharing problem is speculated. Its effects should be measurable in terms of efficiency degradation in a concurrent environment on multicore systems. This article discusses the causes of the false cache line sharing problem in dual-core CPUs, and demonstrates how it lessens the system performance by measuring speed-ups and efficiency of the experiments in sequential compared to parallel executions. Thus, demonstration programs are developed to collect the execution results of the test program with and without false sharing on the specific system hardware. Certain techniques are implemented to eliminate false sharing. These techniques are described, and their effectiveness in mitigating the speed-up and efficiency lost from false sharing is analyzed.