The E ect of Process Switches on Branch PredictionAccuracyT

Recent superscalar processors that use deep pipelines and wide issue rates, highly depend on eecient branch prediction to obtain a large amount of instruction-level parallelism. Much work has been carried out in this area and the outcome of branches is very predictable. Mostly, su-perscalar processors are used in a multiprogram-ming environment to obtain higher throughput. In this paper, we analyze the impact of process switches on prediction accuracy using a simula-tor and show that the accuracy of branch prediction is still high in a multiprogramming environment where process switches occur in the order of milliseconds. However, in multithread-ing architectures, the prediction accuracy will be severely degraded due to the high frequency of process switches.