So my question is this, if all modern day computer CPUs (central processing units) more or less have the same or similar clockspeeds from generation to generation as of late, and all run on a 64 bit architecture with an x86 instruction set, what about the processor is being altered or changed to yield performance gains from one gen to the next?
I understand that more cache is available, and transistor sizes are getting smaller and smaller, but at the end of the day, it is still running an x86 instruction set at 64 bits.
So last gens 4 core 4.5 GHz processor should run identically as quickly as a current gen 4 core 4.5 GHz processor theoretically – but that is not the case.
In: Technology
Even if the operations are the same, you can implement then with different levels of efficiency. Eg, suppose a shift operation. That is, we take a bunch of bits: `00110010` and shift them 1 position to the left: `01100100`. Well, we can do that in different ways. For instance, we could do it digit by digit:
1. Digit 7 moves to digit 8.
2. Digit 6 moves to digit 7
3. Digit 5 moves to digit 6
4. Digit 4 moves to digit 5
5. Digit 3 moves to digit 4
6. Digit 2 moves to digit 3
7. Digit 1 moves to digit 2
8. Fill empty digit 1 with a 0
And that takes us 8 steps. So let’s say 8 clock cycles.
Instead of that you could have 8 copies of the “move digit circuitry”, and perform all of these steps at the same time. Now it takes 1 cycle, but it’s more complex and takes more room. We have 8 times the speed, but it also takes at least 8 times more room.
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