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From: John Heffner <jheffner@psc.edu>
To: Stephen Hemminger <shemminger@osdl.org>
Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org
Subject: Re: [RFC] TCP limited slow start
Date: Sat, 03 Jun 2006 12:46:57 -0400	[thread overview]
Message-ID: <4481BD01.9020906@psc.edu> (raw)
In-Reply-To: <20060602185403.1549e3c6@localhost.localdomain>

Stephen Hemminger wrote:
> Rolled my sleeve's up and gave this a try...
> 
> This is a implementation of Sally Floyd's Limited Slow Start
> for Large Congestion Windows.

Limited slow start is useful as a work-around for bottleneck queues that 
are inappropriately short.  I don't think it's good to run it all the 
time by default (with a max_ssthresh < infinity), because it slows down 
flows on healthy paths, and introduces another non-scalable parameter to 
TCP.

I see it as potentially useful as a per-route parameter, where you set 
it deliberately to work around some known problematic path.  A sysctl 
with a default value of infinity might be okay as well.

Practically speaking, we've had this in the Web100 patch for a long time 
(and still do, look for WAD_MaxSsthresh), but I've never found it all 
that useful.  If the bottleneck queue is too short, you usually end up 
getting screwed other ways too.

   -John

  reply	other threads:[~2006-06-03 16:47 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-06-02 23:13 TCP Limited slow start Stephen Hemminger
2006-06-03  1:54 ` [RFC] TCP limited " Stephen Hemminger
2006-06-03 16:46   ` John Heffner [this message]
2006-06-05 17:17     ` Stephen Hemminger

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