From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
Subject: Re: [9fans] Nagle algorithm
From: nigel@9fs.org
MIME-Version: 1.0
Content-Type: multipart/mixed;
	boundary="upas-aaelpgdyemyflvekjbjvfnxhch"
Message-Id: <20011126110957.7904219A1C@mail.cse.psu.edu>
Date: Mon, 26 Nov 2001 11:09:33 +0000
Topicbox-Message-UUID: 291aad1e-eaca-11e9-9e20-41e7f4b1d025

This is a multi-part message in MIME format.
--upas-aaelpgdyemyflvekjbjvfnxhch
Content-Disposition: inline
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit

Depends on your implementation of write().


--upas-aaelpgdyemyflvekjbjvfnxhch
Content-Type: message/rfc822
Content-Disposition: inline

Received: from mail.cse.psu.edu ([130.203.4.6]) by cpu; Mon Nov 26 11:13:35 GMT 2001
Received: from psuvax1.cse.psu.edu (psuvax1.cse.psu.edu [130.203.20.6])
	by mail.cse.psu.edu (CSE Mail Server) with ESMTP
	id 9AF8619A11; Mon, 26 Nov 2001 06:08:11 -0500 (EST)
Delivered-To: 9fans@cse.psu.edu
Received: from cesium.clock.org (cesium.clock.org [216.240.40.205])
	by mail.cse.psu.edu (CSE Mail Server) with ESMTP id 8434C19A0C
	for <9fans@cse.psu.edu>; Mon, 26 Nov 2001 06:07:35 -0500 (EST)
Received: by cesium.clock.org (Postfix, from userid 42)
	id 08895C7901; Mon, 26 Nov 2001 03:07:28 -0800 (PST)
To: 9fans@cse.psu.edu
Subject: Re: [9fans] Nagle algorithm
References: <20011123115816.4863819A7E@mail.cse.psu.edu>
From: "Sean M. Doran" <smd@cesium.clock.org>
In-Reply-To: <20011123115816.4863819A7E@mail.cse.psu.edu>
 (forsyth@caldo.demon.co.uk's message of "Fri, 23 Nov 2001 11:58:13 0000")
Message-ID: <ytu1vhu6xb.fsf@cesium.clock.org>
Lines: 24
User-Agent: Gnus/5.090004 (Oort Gnus v0.04) Emacs/20.7 (sparc--netbsd)
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Sender: 9fans-admin@cse.psu.edu
Errors-To: 9fans-admin@cse.psu.edu
X-BeenThere: 9fans@cse.psu.edu
X-Mailman-Version: 2.0.7
Precedence: bulk
Reply-To: 9fans@cse.psu.edu
List-Help: <mailto:9fans-request@cse.psu.edu?subject=help>
List-Id: Fans of the OS Plan 9 from Bell Labs <9fans.cse.psu.edu>
List-Archive: <http://lists.cse.psu.edu/archives/9fans/>
Date: Mon, 26 Nov 2001 12:07:28 +0100

forsyth@caldo.demon.co.uk writes:

> ...  Nagle's algorithm for coalescing short segments,
> which is the one that seems ill-advised to me

So, how many packets should the following code segment generate?

    #include <unistd.h>
    /* for int usleep(useconds_t microseconds); */

    for(i=0; i < 200; i++) {
             write(tcpfd, "a", 1);
             usleep(100);
    }

> i do find that quite a lot of this smacks of trying to
> compensate for inadequate data provided by the protocol or the network.

Abstraction and information-hiding are usually considered helpful.
Who wants to muck around with RTT and pMTU in an application
which just might happen to write to a TCP connection?
Perhaps cat(1) isn't complicated enough yet?

     Sean.
--upas-aaelpgdyemyflvekjbjvfnxhch--