From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Heffner Subject: Re: [PATCH] [TCP] Sysctl: document tcp_max_ssthresh (Limited Slow-Start) Date: Fri, 18 May 2007 16:49:08 -0400 Message-ID: <464E1144.4010806@psc.edu> References: <464DE584.7030008@ev-en.org> <464E00E5.5050801@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Baruch Even , =?ISO-8859-1?Q?Ilpo_J=E4rvinen?= , David Miller , Netdev To: Rick Jones Return-path: Received: from mailer1.psc.edu ([128.182.58.100]:58785 "EHLO mailer1.psc.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752203AbXERUtn (ORCPT ); Fri, 18 May 2007 16:49:43 -0400 In-Reply-To: <464E00E5.5050801@hp.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Rick Jones wrote: > as an asside, "tcp_max_ssthresh" sounds like the maximum value ssthresh > can take-on. is that correct, or is this more of a "once ssthresh is > above this, behave in this new way?" If that is the case, while the I don't like it either, but you'll have to talk to Sally Floyd about that one.. ;) In general, I would like the documentation to emphasize more how to set the parameter than describe the algorithm. The max_ssthresh parameter should ideally be set to the bottleneck queue size, or more realistically a conservative value that's likely to be smaller than the bottleneck queue size. When max_ssthresh is smaller than the bottleneck queue, (limited) slow start will not overflow it until cwnd has fully ramped up to the appropriate size. -John