(5 points) from https://developer.arm.com/technologies/big-little “Arm big.LITTL

Question

(5 points) from https://developer.arm.com/technologies/big-little “Arm big.LITTLE technology is a heterogeneous processing architecture which uses two types of processor. ”LITTLE” processors are designed for maximum power efficiency while ”big” processors are designed to provide maximum compute performance. Both types of processor are coherent and share the same instruction set architecture (ISA).” Assume: The big processor core has 4x the capacitance of the little and runs at 1.6V and 1.5GHz The little processor core runs at 1.3V and 500MHz. The big processor consumes _______ times more power than the little processor (answer to nearest integer).

Explanation / Answer

Here in this question we are comparing two processors in which one is big and one is little.

For the big processor:

Capacitance = 4x of little processor

Let’s, Capacitance c = 4x (for big)

Voltage v = 1.6V,

And Frequency f = 1.5GHz = 1.5 * 1000 = 1500 MHz

(here we have converted the frequency from giga to mega Hz because of equilibrium)

For the little processor:

Capacitance c = x (according to the comparison with big one),

Voltage v = 1.3V,

Frequency = 500 MHz,

Now we know that power consumption P

P = f*c*V^2

Where f is frequency, V is voltage & c is the capacitance

Now, Calculate P for big processor

P (big) = f*c*V^2

P(big)= 1500 * 4x * 1.5^2

                = 13,500x

Similarly, for the little processor

P (little) = f*c*V^2

P(little)= 500 * x * 1.3^2

                = 845x

Now compare the both processors: P(big)/P(little)

= 13,500x/845x

=15.97

~16

thus , from this calculation it is clear now that the big processor is consuming almost 16 times more power than little processor.

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