How fast are Linux pipes anyway? (2022)

FWIW there is readv() / writev(), splice(), sendfile(), funopen(), and io_buffer() as well.

splice() is great when transferring data between pipes and UNIX sockets with zero-copy, but it is Linux-only.

splice() is the fastest and most efficient way to transfer data through pipes (on Linux), especially for large volumes. It bypasses memory allocations in userspace (as opposed to read(v)/write(v)), there is no extra buffer management logic, there is no memcpy() or iovec traversal.

Sadly on BSDs, for pipes, readv() / writev() is the most performant way to achieve the same if I am not mistaken. Please correct me if I am wrong.

At any rate, this is a great article.

> sendfile() is file-to-socket (zero-copy as well), and has very high performance as well, for both Linux and BSDs. It only supports file-to-socket, however, and well, to stay relevant, sendmsg() can't be used with pipes in the general case, it is for UNIX domain sockets, INET sockets, and other socket types.

On Linux, sendfile supports more than just file to socket, as it's implemented using splice. I've used it for file-to-block-device in the past.

On BSDs probably not, as they don't have splice, but that is good to know. I wonder if on BSDs it really is readv() and writev() that are the fastest way to achieve the same thing as has been done in the article. Maybe I am missing something. I would like to be corrected.

AFAIK, neither OpenBSD nor NetBSD has sendfile. On FreeBSD, I think you're correct regarding it being file-to-socket only.