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To: pgerassi who wrote (5250)	8/16/2000 9:02:25 PM
From: Petz	Read Replies (1) \| Respond to of 275872

pete, <If all the program fits into the L1 that is the best case for the P4 over the P3, not the worst case> On a % benchmark advantage case, you are right, but I think on a P3 equivalent MHz case, the P4 will look "better" in business benchmarks. Maybe someone else should check my logic, but here goes. Suppose on a CPU-only benchmark that fits in L1, say, CPUMark98, a P4 1.4 GHz only beats a P3 1 GHz by 11% because its IPC is 20% less (0.8 x 1.4 = 1120 equivalent P3 MHz). So we can say that for this type of benchmark, the P4 1.4 GHz is equivalent to a P3 1.12 GHz, meaning that the 1.13 GHz P3 would beat it. On a benchmark that includes 2 main other bottlenecks for completion -- memory access time and I/O time, the CPU can predict a branch wrong once in a while and not suffer any consequences, because its waiting for something else anyway. IOW, the more the potential causes of delay in completing a benchmark, the less often any one of them will be the most significant. So that might make a P4 1.4 GHz appear to be as fast as a P3 1.2 GHz, instead of being as fast as a P3 1.12 GHz CPU. Petz