A method to improve interrupt latency in real-time OS kernels

Interrupt latency has great impact on the real time and predictability of real-time operating system kernels. In traditional implementation of real-time kernels, interrupts are frequently disabled in system service routines, critical sections, etc., which causes kernel interrupt latency. In this paper we propose a method called PIL (Predictive Interrupt Latency). PIL reduces interrupt latency by never disabling interrupts during any system service routines. Moreover, it makes interrupt latency vary little, which improves the predictability in the response time for external events. We have implemented the PIL method in an OSEK-compatible operating system - SmartOSEK OS. Experimental results show PIL improves real time and predictability of real-time systems with low time and space overheads.