Question

Changes in locality for analysis?

Answer 1

The goal of using locality analysis is to eliminate prefetching overhead by prefetching only those references that cause cache misses. To evaluate the effectiveness of this analysis, we performed the following experiment. We implemented a compiler algorithm which prefetches all data references within our domain (i.e. array references whose indices are affine functions of loop indices). We refer to this algorithm as indiscriminate (as opposed to selective) prefetching. The indiscriminate algorithm uses the same software pipelining technique as selective prefetching to schedule prefetches far enough in advance. However, it has no need for locality analysis or loop splitting.

The results of this experiment are shown in Figure 4 and in Tables 3 and 4. The ideal selective prefetch algorithm would achieve the same level of memory stall reduction while decreasing the overheads associated with issuing unnecessary prefetches.