Method, system, and apparatus to improve instruction pre-fetching on computer systems

Abstract

The present invention enables efficient pre-fetching of instructions. The present invention novelly determines a location for insertion of pre-fetch instructions earlier than in the past and in a cost effective manner. Therefore, the present invention introduces more control into the determination of when to initiate instruction pre-fetching than in the past. The present invention pre-fetches instructions accurately and launches instructions early enough to avoid cache miss latency. Also the present invention enables pre-fetching of instructions with the appropriate coverage. The present invention novelly generates pre-fetch instructions that have improved coverage over pre-fetching of the past by testing if the probability of a pre-fetch is cost effective and by determining whether the predicted size of a pre-fetched trace supports cost effective pre-fetching. The present invention assumes the existence of and utilizes the computer-based hardware capabilities of: a computer-based pre-fetch instruction that pre-fetches the cache line corresponding to a particular instruction address, and an augmentation to a computer-based branch instruction that can specify whether sequential instruction pre-fetching should be initiated at the target of a branch instruction.