From owner-svn-src-head@FreeBSD.ORG Sat Sep 13 20:28:22 2014 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id A06B03A4; Sat, 13 Sep 2014 20:28:22 +0000 (UTC) Received: from esa-annu.net.uoguelph.ca (esa-annu.mail.uoguelph.ca [131.104.91.36]) by mx1.freebsd.org (Postfix) with ESMTP id 301B7684; Sat, 13 Sep 2014 20:28:21 +0000 (UTC) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AqIEAI2nFFSDaFve/2dsb2JhbABehDuCeMpngyEBgR54hAQBAQQjVhsYAgINEgcCWQaIUacOlSMBF4EsjW00B4J4gVMFskeCG4FfIYF3gQIBAQE X-IronPort-AV: E=Sophos;i="5.04,518,1406606400"; d="scan'208";a="155012754" Received: from muskoka.cs.uoguelph.ca (HELO zcs3.mail.uoguelph.ca) ([131.104.91.222]) by esa-annu.net.uoguelph.ca with ESMTP; 13 Sep 2014 16:28:20 -0400 Received: from zcs3.mail.uoguelph.ca (localhost.localdomain [127.0.0.1]) by zcs3.mail.uoguelph.ca (Postfix) with ESMTP id DF16CB4039; Sat, 13 Sep 2014 16:28:20 -0400 (EDT) Date: Sat, 13 Sep 2014 16:28:20 -0400 (EDT) From: Rick Macklem To: Hans Petter Selasky Message-ID: <1971026585.35877589.1410640100903.JavaMail.root@uoguelph.ca> In-Reply-To: <5414A5A7.9030108@selasky.org> Subject: Re: svn commit: r271504 - in head/sys: dev/oce dev/vmware/vmxnet3 dev/xen/netfront net netinet ofed/drivers/net/mlx4 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [172.17.91.209] X-Mailer: Zimbra 7.2.6_GA_2926 (ZimbraWebClient - FF3.0 (Win)/7.2.6_GA_2926) Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Adrian Chadd X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 13 Sep 2014 20:28:22 -0000 Hans Petter Selasky wrote: > On 09/13/14 22:04, Rick Macklem wrote: > > Hans Petter Selasky wrote: > >> On 09/13/14 18:54, Adrian Chadd wrote: > >>> Hi, > >>> > >>> Just for the record: > >>> > >>> * I'm glad you're tackling the TSO config stuff; > >>> * I'm not glad you're trying to pack it into a u_int rather than > >>> creating a new structure and adding fields for it. > >>> > >>> I appreciate that you're trying to rush this in before 10.1, but > >>> this > >>> is exactly why things shouldn't be rushed in before release > >>> deadlines. > >>> :) > >>> > >>> I'd really like to see this be broken out as a structure and the > >>> bit > >>> shifting games for what really shouldn't be packed into a u_int > >>> fixed. > >>> Otherwise this is going to be deadweight that has to persist past > >>> 11.0. > >>> > >> > >> Hi Adrian, > >> > >> I can make that change for -current, making the new structure and > >> such. > >> This change was intended for 10 where there is only one u_int for > >> this > >> information. Or do you want me to change that in 10 too? > >> > > Well, there are spare fields (if_ispare[4]) in struct ifnet that I > > believe can be used for new u_ints when MFC'ng a patch that adds > > fields to struct ifnet in head. (If I have this wrong, someone > > please > > correct me.) > > > > I'll admit I don't really see an advantage to defining a structure > > vs > > just defining a couple of additional u_ints, but so long as the > > structure > > doesn't cause alignment issues for any arch, I don't see a problem > > with > > a structure. > > > > I tend to agree with Adrian that this shouldn't be rushed. (I, > > personally, > > think that if_hw_tsomax was poorly chosen, but that is already in > > use, so > > I think we need to add to that and not replace it.) > > > > I also hope that your testing has included quite a bit of activity > > on > > an NFS mount using TSO and the default 64K rsize, wsize, since that > > is > > going to generate a bunch of 35 mbuf transmit fragment lists and > > there > > is an edge case where the total data length excluding ethernet > > header > > is just under 64K (by less than the ethernet header length) where > > the > > list must be split by tcp_output() to avoid disaster. > > Hi, > > The ethernet and VLAN headers are still subtracted. > Where? I couldn't see it when I glanced at the patch. (hdrlen in tcp_output() does not include ethernet header length and that is the only thing I see subtracted from the max_len.) I see the default set to (65536 - 4). I don't know why you subtracted 4 but I would have expected the max ethernet header length to be subtracted here? Note that this must be subtracted before use by tcp_output() because there are several network device drivers that support 32 transmit segments and this means that the TSO segment including ethernet headers must fit in 65536bytes (32 * MCLBYTES). If it does not, then NFS over these devices is busted because even m_defrag() can`t make them fit. rick rick > --HPS > > >