Approximate Microprocessor Technology Trends

Every two or three years,

there were 2× as many transistors:
- 2× as many logic transistors, and
- 2× as much cache memory (SRAM)
the extra logic transistors improved the IPC 1.4×
the transistor switching events per unit of energy improved 2.8×
so even with 2× as many transistors, the frequency could improve 1.4× with the same power
combining the IPC improvement and clock rate improvement, performance increased 2×

there were 2× as many transistors:
- 2× as many logic transistors, and
- 2× as much cache memory (SRAM)
the transistor switching events per unit of energy only improved 2×
so with 2× as many transistors, the frequency had to stay steady to use the same power
that means increasing IPC 1.4× would yield a ho-hum 1.4× performance increase
so instead the extra logic transistors were used for 2× the number of processing cores
which increases the peak throughput 2×, provided all cores can be kept busy
for applications where that works well, it even makes sense to undo earlier IPC improvements:
- use wimpier processing cores
- but more of them

there are 2× as many transistors
but the transistor switching events per unit of energy doesn't even improve 2×
so to keep the power fixed, the number of actively used transistors can't go up 2×
which means even the peak throughput can't go up 2×
unless designers get clever about useful work per switching event
which often means more specialized processing units