Processor capacity reserves: operating system support for multimedia applications

Multimedia applications have timing requirements that cannot generally be satisfied using the time-sharing scheduling algorithms of general purpose operating systems. The authors provide the predictability of real-time systems while retaining the flexibility of a time-sharing system. They designed a processor capacity reservation mechanism that isolates programs from the timing and execution characteristics of other programs in the same way that a memory protection system isolates them from outside memory accesses. In the paper, they describe a scheduling framework that supports reservation and admission control, and introduce a novel reserve abstraction, specifically designed for the microkernel architecture, for measuring and controlling processor usage. The authors have implemented processor capacity reserves in Real-Time Mach, and they describe the performance of their system on several types of applications.<>