A Context Switch Reduction Technique for Real-time Task Synchronization

CPU time spent on switching between concurrent tasks is a pure operating system overhead. This paper describes a technique to reduce the number of context switches caused by task synchronization. Our protocol is applicable to both non-real-time and real-time systems that use preemptive priority scheduling with binary semaphores to enforce mutual exclusion. The protocol does not affect task completion time and so is especially suitable for synchronization where meeting tasks’ timing constraints is more important than other factors such as task response time or throughput. The protocol can be combined with known real-time synchronization policies such as Priority Ceiling Protocol to bound the duration of priority inversion while having the number of context switches reduced.