Fast context switches: compiler and architectural support for preemptive scheduling

This paper addresses the possibility of reducing the overhead due to preemptive context switching in real-time systems that use preemptive scheduling. The method introduced attempts to avoid saving and restoring registers by performing context switches at points in the program where only a small subset of the registers are live. When context switches occur frequently, which is the case in some real-time systems, performing context switches at fast context switch points is found to significantly reduce the total number of memory references. A new optimization technique, known as register remapping, is introduced which increases the number of these fast context switch points without degrading the efficiency of the code.