Mazzoli: How fast are Linux pipes anyway?

Well gee, I thought that's what vmsplice(2) was trying to do in the first place.

But I think the big difference is this: If you e.g. create a file in /dev/shm (or any tmpfs) and just keep writing more and more data to it, it'll get bigger and bigger indefinitely, so you have to periodically seek to zero at both ends (and/or truncate it). Pipes are effectively ring buffers, so they don't have this problem. Your consumer can just call read, and doesn't have to know anything about your fancy mmap nonsense.