Data relocation and prefetching for programs with large data sets

Numerical applications frequently contain nested loop structures that process large arrays of data. The execution of these loop structures often produces memory reference patterns that poorly utilize data caches. Limited associativity and cache capacity result in cache conflict misses. Also, nonunit stride access patterns can cause low utilization of cache lines. Data copying has been proposed and investigated in order to reduce cache conflict misses [1][2], but this technique has a high execution overhead since it performs the copy operations entirely in software. We propose a combined hardware and software technique called data relocation and prefetching which eliminates much of the overhead of data copying through the use of special hardware. Furthermore, by relocating the data while performing software prefetching, the overhead of copying the data can be reduced further. Experimental results for data relocation and prefetching are encouraging and show a large improvement in cache performance.