Hardware locks for a real-time Java chip multiprocessor

摘要

A software locking mechanism commonly protects shared resources for multithreaded applications. Thisrnmechanism can, especially in chip-multiprocessor systems, result in a large synchronization overhead.rnFor real-time systems in particular, this overhead increases the worst-case execution time and may voidrna task set’s schedulability. This paper presents 2 hardware locking mechanisms to reduce the worst-caserntime required to acquire and release synchronization locks. These solutions are implemented for the chipmultiprocessorrnversion of the Java Optimized Processor. The 2 hardware locking mechanisms are comparedrnwith a software locking solution as well as the original locking system of the processor. The hardwarerncost and performance are evaluated for all presented locking mechanisms. The performance of the betterperformingrnhardware locks is comparable with that of the original single global lock when contending forrnthe same lock. When several noncontending locks are used, the hardware locks enable true concurrency forrncritical sections. Benchmarks show that using the hardware locks yields performance ranging from no worsernthan the original locks to more than twice their best performance. This improvement can allow a larger numberrnof real-time tasks to be reliably scheduled on a multiprocessor real-time platform. Copyright © 2016rnJohn Wiley & Sons, Ltd.