Can I use the published clock speed in MHZ of the processor reliably as a relative speed rating?
For back-of-the-envelop capacity planning, it is nice to have a relative speed rating for various processors. You would like to be able to say with confidence that a given processor-bound workload running on machine A running at 400 MHz will execute in 1/3 the time on processor B running at 1.2 GHz that is 3 times faster. For the most part, so long as you stay within the same processor family, you can do that with Intel processors. Benchmark results consistently show that within a processor family, the performance of an Intel processor usually scales linearly with clock speed (in MHz), all other factors like cache size and bus speed being equal. Figure 3 below shows a chart which illustrates this point. Four representative sets of published benchmark results are plotted for Pentium II processors in the range of 300-450 MHz. That performance scales linearly as the clock rate increases is evident. Within a processor family, it is reasonable to expect a Pentium IV at 1.8 GHz to run roughl
