Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754303Ab1ESEdo (ORCPT ); Thu, 19 May 2011 00:33:44 -0400 Received: from mail-yi0-f46.google.com ([209.85.218.46]:40239 "EHLO mail-yi0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752139Ab1ESEdm (ORCPT ); Thu, 19 May 2011 00:33:42 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; b=X+RWCbLXhluS85HL/TLvpMrZZ+yNqXaKfoj0b+hjxBcTkDVRS3dD7ipwaTt2q7iZFA EWYwSI8IzCsaZB9JTasJ2H5/zxuG6DKijE39jRGE3HOno0p7UQ+Agg/1/dSjCgmQkD3D cSw290N2t+ZS7maV/iNvSg0imOFuPEvtRd7NY= MIME-Version: 1.0 In-Reply-To: <20110519.001426.2119532755281545481.davem@davemloft.net> References: <1305771744-83951-1-git-send-email-tsunanet@gmail.com> <20110518.223622.1525088601595365235.davem@davemloft.net> <20110519.001426.2119532755281545481.davem@davemloft.net> From: tsuna Date: Wed, 18 May 2011 21:33:21 -0700 Message-ID: Subject: Re: [PATCH] tcp: Implement a two-level initial RTO as per draft RFC 2988bis-02. To: David Miller Cc: kuznet@ms2.inr.ac.ru, pekkas@netcore.fi, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net, hagen@jauu.net, eric.dumazet@gmail.com, alexander.zimmermann@comsys.rwth-aachen.de, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1648 Lines: 39 On Wed, May 18, 2011 at 9:14 PM, David Miller wrote: > The IETF draft has a requirement that we fallback to 3 seconds if the > initial RTO is 1 second. > > Nothing in your facilities ensure this, or provide a way for the > kernel to make sure this is the case. Not sure to understand what you're saying. If tcp_initial_rto = 1000 and tcp_initial_fallback_rto = 3000, then you get exactly the behavior the draft describes. The knobs simply allow you to either revert to today's behavior or use other settings that would make more sense in your environment (e.g. very high RTT). Are you concerned about cases where, say, tcp_initial_fallback_rto < tcp_initial_rto? > And for other values of initial RTO, what fallback is appropriate? Presumably if the user decides to tweak these knobs, they'll know what's appropriate for their environment. Or are you suggesting that one value be derived from the other? (e.g. tcp_initial_fallback_rto = 3 * tcp_initial_rto) > As a result of all of this, I do not really think this is something > the user should control at all. > > I really would rather see the initial RTO be static and be set to 1 > with fallback RTO of 3. I can also provide a simple patch for this if you want to start from there. And then maybe we can discuss having a runtime knob some more :-) -- Benoit "tsuna" Sigoure Software Engineer @ www.StumbleUpon.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/