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Date:      Sun, 28 Nov 1999 15:06:08 -0800
From:      David Greenman <dg@root.com>
To:        Mohit Aron <aron@cs.rice.edu>
Cc:        freebsd-net@FreeBSD.ORG
Subject:   Re: interaction between Nagle's algorithm and TCP delayed ACKs 
Message-ID:  <199911282306.PAA24795@implode.root.com>
In-Reply-To: Your message of "Sun, 28 Nov 1999 14:27:08 CST." <199911282027.OAA04627@cs.rice.edu> 

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>	FreeBSD-2.2.6 had a macro called ACK_HACK in /sys/netinet/tcp_input.c
>that was effective in avoiding the undesirable interactions between the
>TCP Nagle's algorithm and the delayed ACKs. Basically, if the PUSH flag
>on a packet was set, this macro forced TCP to send an acknowledgment 
>immediately. Since the PUSH flag is usually set on small packets that trigger
>Nagle's algorithm, this macro was effective. 
>
>I checked the code for FreeBSD-3.3 and this macro is no longer there in
>/sys/netinet/tcp_input.c. Can this feature be re-added in later releases.
>In fact, I'd even like it to be turned on by default (it wasn't enabled in
>FreeBSD-2.2.6 by default). 

   I was the one who originally added it and then later removed it. I don't
recall the reason I removed, except perhaps that I thought it wasn't being
used by anyone and was also not something that should be optional. Probably
not a bad idea to just make it the standard behavior.

-DG

David Greenman
Co-founder/Principal Architect, The FreeBSD Project - http://www.freebsd.org
Creator of high-performance Internet servers - http://www.terasolutions.com
Pave the road of life with opportunities.


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