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Date:      Thu, 13 Dec 2001 10:05:01 -0800 (PST)
From:      John Polstra <jdp@polstra.com>
To:        stable@freebsd.org
Cc:        thz@Lennartz-electronic.de
Subject:   Re: TCP stack still hosed?
Message-ID:  <200112131805.fBDI51c14845@vashon.polstra.com>
In-Reply-To: <20011213185153.A365@mezcal.tue.le>
References:  <20011213105451.A738@mezcal.tue.le> <200112131102.fBDB2WQ66827@apollo.backplane.com> <20011213185153.A365@mezcal.tue.le>

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In article <20011213185153.A365@mezcal.tue.le>,
Thomas Zenker  <thz@Lennartz-electronic.de> wrote:
> the most impacting change is in tcp_usrreq.c
> ----------------------------
> revision 1.51.2.10
> date: 2001/11/30 19:54:05;  author: alfred;  state: Exp;  lines: +3 -3
> MFC: 1.64 (larger default tcp send/recieve buffers)
> ----------------------------
> 
> It seems that the switch and/or the USB/ethernet adaptor is overrun
> by the larger sendspace. So setting sysctl net.inet.tcp.xxxspace=16384
> on the USB/ethernet system solves the problem mostly.

Try reducing the sysctl "net.inet.tcp.local_slowstart_flightsize" to 1
or 2.  Does that also solve the problem?

There seems to be mounting evidence that disabling slow start for
local destinations is not a good strategy in general.  It might have
been OK in the days of hubs, but it seems to cause problems with many
switches.

John
-- 
  John Polstra
  John D. Polstra & Co., Inc.                        Seattle, Washington USA
  "Disappointment is a good sign of basic intelligence."  -- Chögyam Trungpa


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