1. Parallel radix sort (CPU or GPU) can also be pretty fast. For input distributions without too much pattern and keys that are not too large, radix sort is pro

1. Parallel radix sort (CPU or GPU) can also be pretty fast. For input distributions without too much pattern and keys that are not too large, radix sort is probably the fastest if you can use it. 2. For typical applications, memory transfer speed matters more than sorting performance on the GPU. If most of your work is done on the CPU, transfering the memory to the GPU may take more time than sorting the array. Not sure if unified memory (apple M series chips and AMD new APU) can remedy this though.