Re: 2.4 delayed acks don't work, fixed

David S. Miller
2003-03-19T00:28:27Z

From: Andrea Arcangeli <andrea@suse.de>
Date: Wed, 19 Mar 2003 01:24:09 +0100

On Wed, Mar 19, 2003 at 01:35:23AM +0300, kuznet@ms2.inr.ac.ru wrote:
> I do not understand this, to be honest. What does clock this sender?
> Some internal clock of sender?

I don't know the details of the userspace, but the data is generated in
real time, it's like if you cat /dev/dsp | netcat -l on the server, and
the receiver does netcat streamer xx >/dev/dsp

This streamer application should buffer at the sending side, in order
to keep the window full. Introducing artificial delays on the sending
side of a unidirectional TCP transfer is really bad for performance
and I can assure you that more than just "weird delayed ACK" behavior
will result.

In fact, it is the most suboptimal way to send data over a TCP socket.
If you can't keep the window full, you do not end up using the
bandwidth available on the path.

I would not be surprised if the news pulling case you mentioned does
something similar.