From owner-freebsd-net@FreeBSD.ORG Mon Jan 7 08:20:39 2013 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id F40E4D76; Mon, 7 Jan 2013 08:20:38 +0000 (UTC) (envelope-from wjw@digiware.nl) Received: from mail.digiware.nl (unknown [IPv6:2001:4cb8:90:ffff::3]) by mx1.freebsd.org (Postfix) with ESMTP id 87D5412A; Mon, 7 Jan 2013 08:20:37 +0000 (UTC) Received: from rack1.digiware.nl (localhost.digiware.nl [127.0.0.1]) by mail.digiware.nl (Postfix) with ESMTP id E799C153434; Mon, 7 Jan 2013 09:20:34 +0100 (CET) X-Virus-Scanned: amavisd-new at digiware.nl Received: from mail.digiware.nl ([127.0.0.1]) by rack1.digiware.nl (rack1.digiware.nl [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id vNUgeDm_0MEJ; Mon, 7 Jan 2013 09:20:34 +0100 (CET) Received: from [127.0.0.1] (opteron [192.168.10.67]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.digiware.nl (Postfix) with ESMTPS id 1B938153433; Mon, 7 Jan 2013 09:20:34 +0100 (CET) Message-ID: <50EA8558.4010600@digiware.nl> Date: Mon, 07 Jan 2013 09:20:40 +0100 From: Willem Jan Withagen Organization: Digiware Management b.v. User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Barney Cordoba Subject: Re: kern/174851: [bxe] [patch] UDP checksum offload is wrong in bxe driver References: <1357399030.5935.YahooMailClassic@web121603.mail.ne1.yahoo.com> In-Reply-To: <1357399030.5935.YahooMailClassic@web121603.mail.ne1.yahoo.com> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Antivirus: avast! (VPS 130106-1, 01/06/2013), Outbound message X-Antivirus-Status: Clean Cc: Garrett Cooper , freebsd-net@freebsd.org, Adrian Chadd , David Christensen , linimon@freebsd.org X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 07 Jan 2013 08:20:39 -0000 On 2013-01-05 16:17, Barney Cordoba wrote: > > > --- On Fri, 1/4/13, Willem Jan Withagen wrote: > >> From: Willem Jan Withagen >> Subject: Re: kern/174851: [bxe] [patch] UDP checksum offload is wrong in bxe driver >> To: "Barney Cordoba" >> Cc: "Garrett Cooper" , freebsd-net@freebsd.org, "Adrian Chadd" , "David Christensen" , linimon@freebsd.org >> Date: Friday, January 4, 2013, 9:41 AM >> On 2013-01-01 0:04, Barney Cordoba >> wrote: >> >>> The statement above "assumes" that there is a benefit. >> voIP packets >>> are short, so the benefit of offloading is reduced. >> There is some >>> delay added by the hardware, and there are cpu cycles >> used in managing >>> the offload code. So those operations not only muddy >> the code, >>> but they may not be faster than simply doing the >> checksum on a much, much >>> faster cpu. >> >> Forgoing all the discussions on performance and possible >> penalties in >> drivers..... >> >> I think there is a large set of UDP streams (and growing) >> that do use >> larger packets. >> >> The video streaming we did used a size of header(14)+7*188, >> which is the >> max number of MPEG packet to fit into anything with an MTU >> < 1500. >> >> Receiving those on small embedded devices which can do HW >> check-summing >> is very beneficial there. >> On the large servers we would generate up to 5Gbit of >> outgoing streams. >> I'm sure that offloading UDP checks would be an advantage as >> well. >> (They did run mainly Linux, but FreeBSD would also work) >> >> Unfortunately most of the infrastructure has been taken >> down, so it is >> no longer possible to verify any of the assumptions. >> >> --WjW > > If you haven't benchmarked it, then you're just guessing. That's my point. > > Its like SMP in freeBSD 4. People bought big, honking machines and the > big expensive machines were slower than a single core system at less than > half the price. Just because something sounds better doesn't mean that it is better. I completely agree.... Dutch proverb goes: "To measure is to know" Which was the subtitle of my graduation report, and my professional motto when working as a systems-architect.... That's why it is sad that the system is no longer up and running, because a 0-order check would be no more that 1 ifconfig would have made a difference. But that is all water under the bridge. --WjW