Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.3 alpha 4/15/85; site ucbvax.ARPA
Path: utzoo!watmath!clyde!burl!ulysses!ucbvax!tcp-ip
From: tcp-ip@ucbvax.ARPA
Newsgroups: fa.tcp-ip
Subject: Tinygrams on 4.2BSD
Message-ID: <7901@ucbvax.ARPA>
Date: Fri, 7-Jun-85 02:36:39 EDT
Article-I.D.: ucbvax.7901
Posted: Fri Jun  7 02:36:39 1985
Date-Received: Sat, 8-Jun-85 01:35:43 EDT
Sender: daemon@ucbvax.ARPA
Organization: University of California at Berkeley
Lines: 17

From: bellcore!karn@BERKELEY (Phil R. Karn)

It is true that TCP on 4.2 effectively does a push every time the user
process does a write() system call. It really has no choice since there are
no semantics by which the user can indicate a push in the write call. But it
doesn't have to be a problem IF programs call the standard I/O library
instead. Stdio tries to fill its 1K buffers completely before calling the
system, and the user is given a push-like subroutine fflush() for when it is
really needed.  The only real offenders (besides character-at-a-time Telnet)
are those few programs that insist on using the bare I/O system calls
directly to write small amounts of data; they should be taken out and shot.
They give lousy performance even when a network isn't involved.

I'm still looking forward to the new version which is rumored to include
John Nagle's transmission algorithms.

Phil