From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751483AbZHRE76 (ORCPT ); Tue, 18 Aug 2009 00:59:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751364AbZHRE75 (ORCPT ); Tue, 18 Aug 2009 00:59:57 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:36822 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751301AbZHRE75 (ORCPT ); Tue, 18 Aug 2009 00:59:57 -0400 Date: Mon, 17 Aug 2009 22:00:08 -0700 (PDT) Message-Id: <20090817.220008.26173943.davem@davemloft.net> To: vda.linux@googlemail.com Cc: tim.bird@am.sony.com, r.schwebel@pengutronix.de, linux-kernel@vger.kernel.org, linux-embedded@vger.kernel.org, arjan@linux.intel.com, kernel@pengutronix.de, netdev@vger.kernel.org Subject: Re: new ipdelay= option for faster netboot From: David Miller In-Reply-To: <200908180656.54011.vda.linux@googlemail.com> References: <4A8A02CA.7040305@am.sony.com> <20090817.182754.50348941.davem@davemloft.net> <200908180656.54011.vda.linux@googlemail.com> X-Mailer: Mew version 6.2.51 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Denys Vlasenko Date: Tue, 18 Aug 2009 06:56:53 +0200 > Since DHCP and any other networking activity like TCP connects > accomodate packet loss, things should work even without any delay > in kernel IP config code. The delay will be just shifted to the > moment when first DHCP/TCP/whatever negotiation happens. Until the link is up, the packet scheduler just holds onto packets and queued them up. When the link comes up, this queue is released and the packets sent out. That's why it's beneficial to wait some time until the link comes up before we start sending stuff out. Because otherwise any timeouts used will be inaccurate. This could code be spiffed up to wait for the link up indication on devices it cares about. Feel free to code that up :-)