From owner-svn-src-head@FreeBSD.ORG Fri Feb 1 21:16:53 2013 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 9FB1DEA5 for ; Fri, 1 Feb 2013 21:16:53 +0000 (UTC) (envelope-from juli@clockworksquid.com) Received: from mail-la0-x236.google.com (la-in-x0236.1e100.net [IPv6:2a00:1450:4010:c03::236]) by mx1.freebsd.org (Postfix) with ESMTP id 2ABCBF26 for ; Fri, 1 Feb 2013 21:16:52 +0000 (UTC) Received: by mail-la0-f54.google.com with SMTP id gw10so3197667lab.13 for ; Fri, 01 Feb 2013 13:16:52 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-received:mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:cc:content-type :x-gm-message-state; bh=X7pXsSJcibOao3bDHR/usd6LUVwttPHjC56c9/DFsW4=; b=CHq3oH/DM7AKKre/izHzvlo4L5fLm3lM+FkzvG7x1hhr+Io6rSPdOGVbHUZHJezpY3 zjDUvGXFaJhYB70RM3oE2Y69lUg86sqz/Ehrge0sdtzfh9vZwpcMv72EmhTEI3FF4wzI fCoAtEa1TsDmgEjftGyp015/rFig4+kZZlnkcc8KOuu6UyK2ATryXRr9OMIt9yFmb0vj kXQqmAf1P52GfSpeQAUDCgq0t+eQhpSXWqXIhaBZBKsfnNJdNoL1Dxvz6UspH8La+qbi q39TACKFk7wT9P7g3fkMgkrbN0Oh1TYgp9KV8P6n8bJDPkJke+o43aw/rZ3CoVkcUFAd TZHg== X-Received: by 10.112.98.71 with SMTP id eg7mr5265035lbb.133.1359753411938; Fri, 01 Feb 2013 13:16:51 -0800 (PST) MIME-Version: 1.0 Sender: juli@clockworksquid.com Received: by 10.152.111.39 with HTTP; Fri, 1 Feb 2013 13:16:31 -0800 (PST) In-Reply-To: <510C2D24.60303@freebsd.org> References: <201302011026.r11AQVL9068427@svn.freebsd.org> <510C00CB.8000409@rice.edu> <510C1E7A.2090509@freebsd.org> <510C2D24.60303@freebsd.org> From: Juli Mallett Date: Fri, 1 Feb 2013 13:16:31 -0800 X-Google-Sender-Auth: toha6PV54ykkDEZYwe9GfBZaMKU Message-ID: Subject: Re: svn commit: r246204 - head/sys/arm/include To: Andre Oppermann Content-Type: text/plain; charset=UTF-8 X-Gm-Message-State: ALoCoQlONtzU53o8waXGQnHDddPBzf6iK5mG3XFzOiGMpiv4JF9+EFjiGp/Jb88jobS1x6roWkxI Cc: svn-src-head@freebsd.org, Adrian Chadd , src-committers@freebsd.org, svn-src-all@freebsd.org, Alan Cox X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.14 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: Fri, 01 Feb 2013 21:16:53 -0000 On Fri, Feb 1, 2013 at 1:01 PM, Andre Oppermann wrote: > On 01.02.2013 21:23, Adrian Chadd wrote: >> >> .. before you make that assumption, please re-visit some the .. >> lower-end integrated ethernet MACs in embedded chips. >> >> I don't know whether the Atheros stuff does (I think it does, but I >> don't know under what conditions it's possible.) >> >> Maybe have it by default not return jumbo mbufs, and if a driver wants >> jumbo mbufs it can explicitly ask for them. > > > Jumbo frames do not see wide-spread use. If they are used, then > in data centre LAN environments and possibly also inter-datacenter. > That is high performance environments. > > I seriously doubt that lower-end ethernet MACs you're referring to > fit that bill. These are silly generalizations, Andre. I know of low-end systems in jumbo frame environments. I think Adrian's implication that Atheros hardware can't handle doing scatter-gather into multiple buffers for jumbo frames is probably an unlikely one, but if we have hardware that requires jumbo mbufs, we should obviously keep supporting jumbo mbufs to some extent. Hypotheticals are somewhat irrelevant, but I find it surprising that you're being so glib about breaking FreeBSD networking just because of an idea you have about where jumbo frame use is appropriate and what kinds of hardware should be connected to jumbo frame networks.