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From: John Heffner <jheffner@psc.edu>
To: "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi>
Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org
Subject: Re: [PATCH net-2.6 0/3]: Three TCP fixes
Date: Tue, 04 Dec 2007 13:42:41 -0500	[thread overview]
Message-ID: <47559FA1.2090104@psc.edu> (raw)
In-Reply-To: <11967869303114-git-send-email-ilpo.jarvinen@helsinki.fi>

Ilpo Järvinen wrote:
> ...I'm still to figure out why tcp_cwnd_down uses snd_ssthresh/2
> as lower bound even though the ssthresh was already halved, 
> so snd_ssthresh should suffice.

I remember this coming up at least once before, so it's probably worth a 
comment in the code.  Rate-halving attempts to actually reduce cwnd to 
half the delivered window.  Here, cwnd/4 (ssthresh/2) is a lower bound 
on how far rate-halving can reduce cwnd.  See the "Bounding Parameters" 
section of <http://www.psc.edu/networking/papers/FACKnotes/current/>.

   -John

  parent reply	other threads:[~2007-12-04 18:52 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-12-04 16:48 [PATCH net-2.6 0/3]: Three TCP fixes Ilpo Järvinen
2007-12-04 16:48 ` [PATCH 1/3] [TCP] FRTO: Use of existing funcs make code more obvious & robust Ilpo Järvinen
2007-12-04 16:48   ` [PATCH 2/3] [TCP]: Move prior_in_flight collect to more robust place Ilpo Järvinen
2007-12-04 16:48     ` [PATCH 3/3] [TCP]: NAGLE_PUSH seems to be a wrong way around Ilpo Järvinen
2007-12-05 10:26       ` David Miller
2007-12-05 11:18         ` Ilpo Järvinen
2007-12-05 11:33           ` David Miller
2007-12-05 10:21     ` [PATCH 2/3] [TCP]: Move prior_in_flight collect to more robust place David Miller
2007-12-05 10:21   ` [PATCH 1/3] [TCP] FRTO: Use of existing funcs make code more obvious & robust David Miller
2007-12-04 18:42 ` John Heffner [this message]
2007-12-04 21:10   ` [PATCH net-2.6 0/3]: Three TCP fixes Ilpo Järvinen
2007-12-04 21:17     ` John Heffner
2007-12-04 21:26       ` Ilpo Järvinen
2007-12-05 11:17         ` Alexey Kuznetsov
2007-12-05  2:13       ` Matt Mathis
2007-12-05 10:30   ` David Miller
2007-12-05 11:30     ` Ilpo Järvinen
2007-12-06  4:56       ` David Miller

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