From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753494Ab0BRIoc (ORCPT ); Thu, 18 Feb 2010 03:44:32 -0500 Received: from mail-forward2.uio.no ([129.240.10.71]:57750 "EHLO mail-forward2.uio.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753067Ab0BRIoa (ORCPT ); Thu, 18 Feb 2010 03:44:30 -0500 Message-ID: <4B7CFDE4.4010003@simula.no> Date: Thu, 18 Feb 2010 09:44:20 +0100 From: Andreas Petlund User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9pre) Gecko/20100209 Shredder/3.0.2pre MIME-Version: 1.0 To: =?ISO-8859-1?Q?Ilpo_J=E4rvinen?= CC: Netdev , eric.dumazet@gmail.com, hannemann@nets.rwth-aachen.de, LKML , shemminger@vyatta.com, william.allen.simpson@gmail.com, damian@tvk.rwth-aachen.de, ebiederm@xmission.com, David Miller Subject: Re: [net-next PATCH v4 2/3] net: TCP thin linear timeouts References: <4B7AAE69.8020701@simula.no> <20100217.163255.133898079.davem@davemloft.net> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-UiO-Ratelimit-Test: rcpts/h 11 msgs/h 2 sum rcpts/h 13 sum msgs/h 2 total rcpts 868 max rcpts/h 40 ratelimit 0 X-UiO-Spam-info: not spam, SpamAssassin (score=-5.0, required=5.0, autolearn=disabled, UIO_MAIL_IS_INTERNAL=-5, uiobl=NO, uiouri=NO) X-UiO-Scanned: AD82387E4C5CCED76912D000ECAF026AB80DE4F7 X-UiO-SPAM-Test: remote_host: 128.39.37.254 spam_score: -49 maxlevel 80 minaction 2 bait 0 mail/h: 23 total 20643 max/h 66 blacklist 0 greylist 0 ratelimit 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/18/2010 09:41 AM, Ilpo Järvinen wrote: > On Wed, 17 Feb 2010, David Miller wrote: > >> From: Andreas Petlund >> Date: Tue, 16 Feb 2010 15:40:41 +0100 >> >>> @@ -341,6 +342,8 @@ struct tcp_sock { >>> u16 advmss; /* Advertised MSS */ >>> u8 frto_counter; /* Number of new acks after RTO */ >>> u8 nonagle; /* Disable Nagle algorithm? */ >>> + u8 thin_lto : 1,/* Use linear timeouts for thin streams */ >>> + thin_undef : 7; >>> >> >> There is now a gap of 3 unused bytes here in this critical >> core TCP socket data structure. >> >> Please either find a way to avoid this hole, or document >> it with a comment. > > There would be multiple bits free for use in both frto_counter and nonagle > byte. > I was playing aroud with this setup: ========= u8 nonagle : 4,/* Disable Nagle algorithm? */ thin_lto : 1,/* Use linear timeouts for thin streams */ thin_dupack : 1,/* Fast retransmit on first dupack */ thin_undef : 2; ========= Do you think that would do the trick? Regards, Andreas