CPU SIMD vs GPU SIMD?

Question

GPU uses the SIMD paradigm, that is, the same portion of code will be executed in parallel, and applied to various elements of a data set.

However, CPU also uses SIMD, a

Answer 1

It's a similar idea, it goes kind of like this (very informally speaking):

• The CPU has a set amount of functions that can run on packed values. Depending on your brand and version of your CPU, you might have access to SSE2, 3, 4, 3dnow, etc, and each of them gives you access to more and more functions. You're limited by the register size and the larger data types you work with the less values you can use in parallel. You can freely mix and match SIMD instructions with traditional x86/x64 instructions.
• The GPU lets you write your entire pipeline for each pixel of a texture. The texture size doesn't depend on your pipeline length, ie the number of values you can affect in one cycle isn't dependant on anything but your GPU, and the functions you can chain (your pixel shader) can be pretty much anything. It's somewhat more rigid though in that the setup and readback of your values is somewhat slower, and it's a one shot process (load values, run shader, read values), you can't massage them at all besides that, so you actually need to use a lot of values for it to be worth it.