Big/Little Proposition

(Not examinable for this course.)

The following plot has two salient features:

Firstly, a high-performance CPU contains a lot of ancillary logic to achieve this performance (reorder buffers etc.).

Two smaller CPUs give twice the performance of a single smaller CPU at exactly twice the power.

Secondly, all three configurations illustrate performance can be changed as V and F parameters are varied, but the performance gain requires super-linear power use.

Relative performance of simple and complex CPU cores subject to DVFS.

ARM has its big.LITTLE system where CPU state is shunted between different core designs as the measured load varies. »big.LITTLE ProcessingBut it is better to write a parallel program if you can and then use multiple simple cores.