Multiscalar execution along a single flow of control

Abstract

The multiscalar processing model extracts instruction level parallelism from ordinary programs by splitting the program into smaller, possibly dependent, tasks, and parallelly executing multiple tasks using multiple execution units. Past work had advocated pursuing multiple flows of control in the multiscalar processor. We first illustrate the problems involved in pursuing multiple flows of control. We then discuss a methodology to obtain good performance from multiple tasks extracted from a single line of control. We also present the results of simulation studies that verify the potential of this method. These results, obtained with a set of SPECS92 benchmarks, show better issue rates when a single line of control is pursued in the multiscalar processor. The primary reason for this improvement is the ability to have better load balancing among the execution units.