A simpler way to add pipelining to 9P is to define that multiple outstanding messages with the same tag are allowed and that the server must process and respond to messages with a given tag in the order it receives them. This only requires changes to servers that are actually multithreaded. All the tiny servers only do one message at a time anyway.
Given that extension, you can just send Twalk Topen Twrite Tclunk back to back with a single tag and then process the four replies. This was proposed at the Spain IWP9. Russ
