One of the other constraints is the actual data copy. I don't have any benchmarks on hand, but you pay the penalty for the copy, potentially cache misses, and

One of the other constraints is the actual data copy. I don't have any benchmarks on hand, but you pay the penalty for the copy, potentially cache misses, and the potential TLB miss. Obviously, there are ways to avoid it without resorting to bypassing the kernel, but there's still a non-negligible cost. Maybe it would be beneficial to have a coherent interface as well, considering NVMe.