Internal Scheduling and Memory Contention

It has been suggested that the algorithm used to schedule those processes active and in main memory can have an effect on memory contention. We create models for memory contention in a system that uses global LRU replacement and either round robin or priority internal scheduling. Parameters to our model include the ratio of secondary storage to primary storage access times, thus allowing consideration of a variety of storage technologies. The round robin quantum size is included and is shown to have some effect. Our model uses LRU miss ratio curves and thus reflects actual program characteristics. Trace driven simulations are used to verify the accuracy of the models. We find that in most cases internal scheduling has only a small effect on page fault rates and CPU utilization. In certain cases, however priority scheduling is found to besignificant in relieving thrashing.