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But there are also different types of speed. [[interrupt latency|Interrupt latency]] is the guaranteed maximum response time of the system to an electronic event (e.g. when the disk drive finishes moving some data). This number is affected by a very wide range of design choices. Computers that control machinery usually need low interrupt latencies, because the machine can't, won't or should not wait. For example, computer-controlled anti-lock brakes should not wait for the computer to finish what it's doing - they should brake. Low latencies can often be had very inexpensively.
[[benchmark|Benchmarking]] tries to take all these factors into account by measuring the time a computer takes to run through a series of test programs. Although benchmarking shows strengths, it may not help one to choose a computer. Often the measured machines split on different measures. For example, one system might handle scientific applications quickly, while another might play popular video games more smoothly. Furthermore, designers have been known to add special features to their products, whether in hardware or software, features which permit a specific benchmark to execute quickly but which do not offer similar advantages to other, more general computational tasks. Naïve users are apt to be unaware of such deceptive tricks.
The general scheme of optimization is to find the costs of the different parts of the computer. In a balanced computer system, the data rate will be constant for all parts of the system, and cost will be allocated proportionally to assure this. The exact form of the computer system will depend on the constraints and goals it was optimized for.
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