He strongly believes that something like rep stos/rep mov is the right interface for memset/memcpy and off-core accelerators (like DMA) are misguided.
His reasoning or rant for this?
I'm not sure about Linus's objections, but I've found that DMA accelerators for time sharing systems with general workloads haven't reaped benefits, as the overhead of multiplexing and synchronizing with them kills most of their benefits. At that point it's easier to blit memory yourself.