From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH 0/3] [v3] Revert Backoff on ICMP destination unreachable Date: Sun, 30 Aug 2009 21:56:29 -0700 (PDT) Message-ID: <20090830.215629.259434175.davem@davemloft.net> References: <4A950B76.1070002@tvk.rwth-aachen.de> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, ilpo.jarvinen@helsinki.fi To: damian@tvk.rwth-aachen.de Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:60960 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752475AbZHaE4P (ORCPT ); Mon, 31 Aug 2009 00:56:15 -0400 In-Reply-To: <4A950B76.1070002@tvk.rwth-aachen.de> Sender: netdev-owner@vger.kernel.org List-ID: From: Damian Lukowski Date: Wed, 26 Aug 2009 12:16:22 +0200 > This series of patches implements the TCP improvement of the Internet Draft > "Make TCP more Robust to Long Connectivity Disruptions" > (http://tools.ietf.org/html/draft-zimmermann-tcp-lcd). > > Exponential backoff is TCP's standard behaviour during long connectivity > disruptions, which is a countermeasure against network congestion. > If congestion can be excluded as the reason for RTO retransmission loss, > backoff is not desirable, as it yields longer TCP recovery times, when > the communication path is repaired shortly after an unsuccessful > retransmission probe. > > 1) This patch renames the skb in tcp_v4_err() in preparation for patch 2. > 2) Contains the main reversion logic. > Reintroduces tcp_bound_rto() and __tcp_set_rto() > 3) This patch modifies the interpretation of the tcp_retries{1,2} sysctls. > It became necessary because with patch2 the assumption that the number > of retransmits corresponds to an specific timeout value is not accurate > anymore. With this patch tcp_retries{1,2} specifies a timeout value, > equivalent to the time a connection with an rto value of MIN_RTO (200ms) > would need to retransmit N segments. IOW: The meaning (in sense of time) > is mostly preserved, but the actual connection timeout does not depend > on the calculated rto of the connection, anymore. > > Signed-off-by: Damian Lukowski Ilpo can you please review this new version of Damian's changes? Thanks.