[cogman10]

And, TBF, a lot of the IO stuff comes down to specifically talking about what sort of device you are talking to and where.

For a lot of the programming I do (and I'm sure a lot of others on HN) IO is almost all network IO. For that, because it's so slow and everything is working over DMA anyways, coroutines end up working really well.

However, once you start talking about on system resources such as SSDs or the GPU, it gets more tricky. As you rightly point out, the GPU is especially bad because all GPU communication ends up being routed through the CPU. At least for a HD, there's DMA which cuts down on the amount of CPU work that needs to be done to access a bit of data.