Comment by mathisfun123

> GPUs aren't really SIMD, they're SIMT (single instruction multiple thread)

False. If they were threads they'd have their own PC. They do not - only the warp has a PC.

> You just write plain scalar code and the hardware model dispatches it efficiently to SIMD execution units.

Absolutely not. If you don't write coalesced loads, bank-conflict free, predication-free, cooperative code you will get worse than CPU performance.