From owner-freebsd-net@FreeBSD.ORG Wed Oct 19 19:12:40 2011 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 7B1B6106566B; Wed, 19 Oct 2011 19:12:40 +0000 (UTC) (envelope-from bhutchings@solarflare.com) Received: from exchange.solarflare.com (mail.solarflare.com [216.237.3.220]) by mx1.freebsd.org (Postfix) with ESMTP id 360E18FC24; Wed, 19 Oct 2011 19:12:39 +0000 (UTC) Received: from [10.17.20.137] ([10.17.20.137]) by exchange.solarflare.com over TLS secured channel with Microsoft SMTPSVC(6.0.3790.4675); Wed, 19 Oct 2011 12:12:39 -0700 From: Ben Hutchings To: "Bjoern A. Zeeb" In-Reply-To: <68546593-B3E1-44D8-B512-4FD99B90D989@lists.zabbadoz.net> References: <1317309906.2743.9.camel@bwh-desktop> <1318865394.2784.4.camel@bwh-desktop> <4E9C534D.4090405@freebsd.org> <1318894136.2784.76.camel@bwh-desktop> <68546593-B3E1-44D8-B512-4FD99B90D989@lists.zabbadoz.net> Content-Type: text/plain; charset="UTF-8" Organization: Solarflare Communications Date: Wed, 19 Oct 2011 20:12:30 +0100 Message-ID: <1319051550.2829.34.camel@bwh-desktop> Mime-Version: 1.0 X-Mailer: Evolution 2.32.2 (2.32.2-1.fc14) Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 19 Oct 2011 19:12:39.0415 (UTC) FILETIME=[11A34070:01CC8E93] X-TM-AS-Product-Ver: SMEX-8.0.0.1181-6.500.1024-18458.005 X-TM-AS-Result: No--21.361400-0.000000-31 X-TM-AS-User-Approved-Sender: Yes X-TM-AS-User-Blocked-Sender: No Cc: freebsd-net@freebsd.org, Andre Oppermann Subject: Re: TSO broken with jumbo MTU X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 19 Oct 2011 19:12:40 -0000 On Mon, 2011-10-17 at 23:59 +0000, Bjoern A. Zeeb wrote: > On 17. Oct 2011, at 23:28 , Ben Hutchings wrote: > > > On Mon, 2011-10-17 at 18:09 +0200, Andre Oppermann wrote: > >> On 17.10.2011 17:29, Ben Hutchings wrote: > >>> This is the fix/workaround I used: > >> > >> Thanks for the fix. I'll review it and put it into FreeBSD maybe in > >> a slightly different form. > > > > Which one? One is tested but maybe not right; the other looks right but > > is not tested! > > and here's the real question -- was it always broken or did a commit during > the last years introduce the problem? t_maxopd > t_maxseg has always been possible since t_maxopd was added: http://svnweb.freebsd.org/base?view=revision&revision=6247 http://svnweb.freebsd.org/base?view=revision&revision=6283 The commit introducing TSO support was: http://svnweb.freebsd.org/base?view=revision&revision=162110 and that already had the problem that TSO may be selected for an mbuf that only requires one segment if t_maxopd > t_maxseg. The assertion that failed was added in: http://svnweb.freebsd.org/base?view=revision&revision=211317 As to which of these is the real bug, I cannot say. The commit message for the last change hopefully provides a clue for those more familiar with this TCP implementation. Ben. -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.