Java Technologies for Real-Time and Embedded Systemsrn(JTRES2013)

摘要

This outline describes a special issue of papers from the 2013 workshop on Java Technologies forrnReal-Time and Embedded Systems [1]. There are 2 papers in this special issue.rnThe first paper [2] discusses software locking mechanisms that commonly protect shared resourcesrnfor multithreaded applications. This mechanism can, especially in chip-multiprocessor systems, resultrnin a large synchronization overhead. For real-time systems in particular, this overhead increases thernworst-case execution time and may void a task set’s schedulability. This paper presents 2 hardwarernlocking mechanisms to reduce the worst-case time required to acquire and release synchronizationrnlocks. These solutions are implemented for the chip-multiprocessor version of the Java OptimizedrnProcessor. The 2 hardware locking mechanisms are compared with a software locking solution asrnwell as the original locking system of the processor. The hardware cost and performance arernevaluated for all presented locking mechanisms. The performance of the better performing hardwarernlocks is comparable to the original single global lock when contending for the same lock. Whenrnseveral noncontending locks are used, the hardware locks enable true concurrency for criticalrnsections. Benchmarks show that using the hardware locks yields performance ranging from nornworse than the original locks to more than twice their best performance. This improvement canrnallow a larger number of real-time tasks to be reliably scheduled on a multiprocessor real-timernplatform.