Why can’t manufacturers just add more CPU’s to make the computer faster?

Question

Why does

Two CPU’s != Twice the power

In: Technology

Answer 1

There’s a concept called parallelization, which is how well a task can be split up into completely independent tasks. Let’s look at two sets of math calculations run with two CPUs

x=y+3

z=2*x

We assign the first equation to CPU 1 and it gets to work. However, we can’t assign the second one to CPU 2. This is because the second equation needs the answer from the first equation. So CPU 2 doesn’t do anything.

Let’s look at a second set.

x=y+3

z=2*q

We assign the first equation to CPU 1 just like before. Now equation 2 doesn’t require equation 1 to be solved first. Now we can assign CPU 2 to run equation 2 at the same time.

We can extend this concept to more general tasks. Some tasks benefit from more CPUs and some don’t. Play music and watch a video at the same time? parallel, 1 CPU plays music and the other plays the video. Run a physics simulation of a bouncing ball? Not parallel (simplifying). You can’t calculate what happens at second 10 without finding what happens at second 1.