From mboxrd@z Thu Jan 1 00:00:00 1970 From: OBATA Noboru Subject: Re: [PATCH 2.6.22] TCP: Make TCP_RTO_MAX a variable (take 2) Date: Tue, 24 Jul 2007 22:35:58 +0900 (JST) Message-ID: <20070724.223558.73364253.noboru.obata.ar@hitachi.com> References: <20070712.161510.26510093.noboru.obata.ar@hitachi.com> <20070712.023710.36923635.davem@davemloft.net> <46969460.3020604@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, shemminger@linux-foundation.org, yoshfuji@linux-ipv6.org, netdev@vger.kernel.org To: rick.jones2@hp.com Return-path: Received: from mail9.hitachi.co.jp ([133.145.228.44]:34737 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752150AbXGXNgB (ORCPT ); Tue, 24 Jul 2007 09:36:01 -0400 Received: from mlsv13.hitachi.co.jp (unknown [133.144.234.166]) by mail9.hitachi.co.jp (Postfix) with ESMTP id 9925637C87 for ; Tue, 24 Jul 2007 22:35:59 +0900 (JST) In-Reply-To: <46969460.3020604@hp.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Rick Jones Subject: Re: [PATCH 2.6.22] TCP: Make TCP_RTO_MAX a variable (take 2) Date: Thu, 12 Jul 2007 13:51:44 -0700 > > TCP's timeouts are perfectly fine, and the only thing you > > might be showing above is that the application timeouts > > are too short or that TCP needs notifications. > > The application timeouts are probably being driven by external desires > for a given recovery time. Agreed. > TCP notifications don't solve anything unless the links in question are > local to the machine on which the TCP endpoint resides. Agreed. Thank you for a good explanation. My original discussion using Dom-0 and Dom-U might be misleading, but I was trying to say: * Network failure and recovery(failover) are not necessarily visible locally. ** Dom-0 vs. Dom-U discussion is just an example of the case where a network failure is not visible locally. ** For another example, network switches or routers sitting somewhere in the middle of route are often duplicated with active-standby setting today. * Quick response (retransmission) of TCP upon a recovery of such invisible devices as well is desired. * If the failure and recovery are not visible locally, TCP notifications do not help. Regards, -- OBATA Noboru (noboru.obata.ar@hitachi.com)