What is relation between MCPS(million cycles per second) and power consumed

Question

Hello,

 I have been working on a ARM cortex A8 board on mp3 decoder.

While doing this i have a requirement saying the mp3 decoder solution i am doing should consume 50 milli-watts of power. This generated few questions in my mind when i thought about it:-

1.) I recall that there is some relation between the Core Voltage applied(V), the clock frequency(f) of a processor and power consumed(P) as something like P is directly proportional to the voltage and frequency squared. But is the exact relation. Given operating clock Frequency, voltage of a processor, how can we calculate power consumed by it.

2.) Now if i get the power consumed from step 1.) at some clock frequency, and i am told that the decoder solution i am giving, can consume only 50 milli-watts, how can i get the maximum limit on MCPS, which will be the upper bound on the MCPS of my decoder solution running on that hardware board?

Can i deduce that if power obtained as in step 1.) say P, is consumed at frequency F, so for 50 milli-watts power, what is clock frequency frequency and calculate accordingly the frequency. And then call this frequency as my code MHz (MCPS) upper bound?

Basically how does one map(is there any equation) power consumed by a software to MCPS consumed

I hope this is relevant here, or should it go to superuser?

Thank you. -AD.

Answer 1

It really depends on the architecture.

From their own page:

Core area, frequency range and power consumption are dependent on process, libraries and optimizations.

Power with cache (mW/MHz) <0.59 <0.45

Basically, it states that you can't accurately calculate the power consumption, so your best bet would be to do some measurements yourself. Try to run a full CPU-usage application and meassure the power consumption. It will give you some idea of the max-load, which will be a good start for you (to know how much you need to optimize your code and insert idle points).