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Date: Mon, 21 Apr 2003 10:24:59 -0700
From: Terry Lambert <tlambert2@mindspring.com>
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cc: "Jin Guojun \[NCS\]" <j_guojun@lbl.gov>
Subject: Re: patch for test (Was: tcp_output starving -- is due to mbuf get 
 delay?)
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Borje Josefsson wrote:
[ ... Jin Guojun's TCP output patch for high bandwidth delay product ... ]

> This patch definitively works, and gives much higher PPS (32000 instead of
> 19000). This is on a low-end system (PIII 900MHz with 33MHz bus), I'll
> test one of my larger systems later today.
> 
> One question though - is there any way of having the code being more
> "aggressive"? As You see, in the netstat output below, it takes ~35
> seconds(!) before reaching full speed. On NetBSD I reach maxPPS almost
> immediately. Even if we now (with Your patch) can utilize the hardware
> much more, it only helps if You have connections that lasts for a very
> long time, so that the "ramping" time is not significant.


You can get immediate relief by porting this code instead of
using the patch:

	http://www.psc.edu/networking/tcp.html#psc

It is for NetBSD 1.3.2, and includes a SACK, Rate Halving,
auto-tuning, and explicit congestion notification:

Description:

	http://www.psc.edu/networking/rate_halving.html

Direct link to the code:

	http://www.psc.edu/networking/ftp/tools/netbsd132_rh_10.tgz

Also included is a FACK implementation.

-- Terry