Speculative prefetching

A hardware prefetching mechanism named Speculative Prefetching is proposed. This scheme detects vector accesses issued by a load/store instruction and prefetches the corresponding data. The scheme requires no software add-on, and in some cases it is more powerful than software techniques for identifying regular accesses. The tradeoffs related to its hardware implementation are extensively discussed in order to finely tune the mechanism. Experiments show that average memory access time of regular codes is brought within 10% of optimum for processors with usual issue rates, while performance of irregular codes is little reduced though never degraded. The scheme performance is discussed over a wide range of parameters.

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