Comment Performance per watt? (Score 3, Interesting) 515
Maybe I'm missing something, but I don't understand how performance per watt is useful as *the* statistic for comparing processors. Granted, clockspeeds aren't the law of the land, but at least they gave you some idea of how processors stack up against each other. The lines have become fuzzier recently, but I can know with a resonable amount of certaintly that a 3ghz P4 will kick the living daylight out of a 1mhz CPU.
Performance per watt tells a different story. While performance return per unit power consumed may tell how efficient a processor is, it doesn't tell me how good a processor is at doing what I want it to -- crunch numbers, really fast.
Performance per watt is a ratio, so the rating can increase when performance increases or power consumption decreases. Therefore, a solar calculator with a 5mhz processor and (I'm making this up) 0.1 watt power consumption would have a 50 mhz/watt rating, and a 3ghz CPU with a 100 watt consumption would have a rating of 30 mhz/watt. So, now Intel sells both these processors and advertises their performance/watt ratings. When someone goes to buy a new computer, they're surprised to find that the 50 mhz/watt computer is actually slower/worse/crappier than the 30 mhz/watt one.
A rock has infinite performance per power usage. It performs one instruction using no power.
Performance per watt tells a different story. While performance return per unit power consumed may tell how efficient a processor is, it doesn't tell me how good a processor is at doing what I want it to -- crunch numbers, really fast.
Performance per watt is a ratio, so the rating can increase when performance increases or power consumption decreases. Therefore, a solar calculator with a 5mhz processor and (I'm making this up) 0.1 watt power consumption would have a 50 mhz/watt rating, and a 3ghz CPU with a 100 watt consumption would have a rating of 30 mhz/watt. So, now Intel sells both these processors and advertises their performance/watt ratings. When someone goes to buy a new computer, they're surprised to find that the 50 mhz/watt computer is actually slower/worse/crappier than the 30 mhz/watt one.
A rock has infinite performance per power usage. It performs one instruction using no power.
