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Show To measure the effect of problem size on history cache performance, the problem size was varied for a fixed cache organization. The history cache was set to 512 cache entries, the set size to 8 and the line size to 4 bytes. The size of the N-queens program and the scientific simulation was varied in powers of 2 from 2° to 210. The largest programs occupied around 8 Mbytes of main memory. Memory consumption and the number of executed instructions scale linearly with the size of the problem for both programs. Results are shown in Figure 5.14. The History Ratio shows the number of history elements produced by one instruction. The largest N-queens program produces 80.5 Mbytes of history data in 720,000,000 instructions. The largest scientific simulation produces 88 Mbytes of history data in 2,340,000,000 instructions. The performance of the history cache degrades slowly with increasing problem size, since the degradation 144 Problem Size in Powers of 2 Figure 5.14. History Ratio (History Elements/Executed Instructions) as a Function of the Size of the Problem |
