Computer architecture: Difference between revisions

Revision as of 11:46, 21 July 2002

Revision as of 03:00, 13 November 2002

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2. Performance

Computer retailers describe the performance of their machines in terms of clock speed (usually in MHz or GHz). This refers to the cycles per second of the main clock of the CPU. However, this metric is somewhat misleading, as a machine with a higher clock rate may not necessarily have higher performance. Most modern CPUs are capable of [[superscalar|executing multiple instructions per clock cycle (see [[superscalar]]), which can havedramaticallly a dramatic effect on how quicklyspeed-up a program. can run,Other asfactors canaid other factorsspeed, such as the mix of [[functional unit]]s, [[computer bus|bus]] speeds, available memory, and the type and order of instructions in the programs being run.

Better metrics can be obtained by [[benchmark]]ing, which attempts to take all these factors into account by measuring the time the system takes to run through a series of provided programs. This can be used to obtain an average throughput for the system. Even still, benchmarking may not show that one of two systems is clearly better, since one system may, for example, be optomized to handle scientific applications, and another may be optomized to play popular video games.