From owner-freebsd-net@FreeBSD.ORG Wed Feb 26 18:28:00 2014 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 37FF86C8 for ; Wed, 26 Feb 2014 18:28:00 +0000 (UTC) Received: from mail-ve0-x234.google.com (mail-ve0-x234.google.com [IPv6:2607:f8b0:400c:c01::234]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id E99C119B3 for ; Wed, 26 Feb 2014 18:27:59 +0000 (UTC) Received: by mail-ve0-f180.google.com with SMTP id jz11so2525618veb.25 for ; Wed, 26 Feb 2014 10:27:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=nb/rSiZdgM95+2wPRuMxDCaqCAMyVFgm8ZTHRRoLIYM=; b=Aix5uFNxusA+vrKzLstZwWu+TVfuQd3HdBuCJ46jAoC361PgurdwQ49DTh7ACOayzh X7iw/xvrLpmeeUBoMpaHdQcN1tDEEhPGhdDk1Y1g4xPwc/Ivi/ibwOsBrz2AtDw9AGgN SsWoz7KqNFWHxdvk7M6efKFeLlQHO2VqBCNynb2jhOne8CKVBFvqrcAGyhsZFaA/Iu83 M2oWVQ4XL61iCy9OdWpxS+2ov1iQtPBiWVl0rMKoivzN+h1HI+GF5YOtNiyN1Bi8oVfI 5aPAnxmklVspZRJfafxvXYKi5wupJ/nYjZNBcwKqDJ8XbEuLsu5OkFPKt9a3uLFbeMC9 LPiQ== MIME-Version: 1.0 X-Received: by 10.52.242.167 with SMTP id wr7mr5895088vdc.32.1393439279112; Wed, 26 Feb 2014 10:27:59 -0800 (PST) Received: by 10.221.11.135 with HTTP; Wed, 26 Feb 2014 10:27:59 -0800 (PST) In-Reply-To: <20140226180736.GV92037@funkthat.com> References: <20140226180736.GV92037@funkthat.com> Date: Wed, 26 Feb 2014 10:27:59 -0800 Message-ID: Subject: Re: TSO From: Jack Vogel To: Sami Halabi , FreeBSD Net Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.17 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.17 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, 26 Feb 2014 18:28:00 -0000 Drivers have to work with whatever the requirements/limitations of the hardware, if you have a 5 lb sack you shouldn't be surprised if some drops when you shove 6 lbs at it :) Why not have this limit in the interface so the stack can avoid exceeding it? Jack On Wed, Feb 26, 2014 at 10:07 AM, John-Mark Gurney wrote: > Sami Halabi wrote this message on Wed, Feb 26, 2014 at 19:37 +0200: > > I'm reading (almost) all mailing emails in mailig list... > > > > Almost every / many problem in network performancr / packets loss ended > up > > suggesting disabling TSO. > > > > I wonder why.. Is it a bug in the implementation? Or bybdesign? > > What are the usecases that TSO is needed? Myabe it should be disabled bt > > default? > > It looks like most of the problems are in drivers that don't handle > packets with a large number of segments properly... The problem is > that some drivers limit to how segments a packet can be broken into, and > then if they receive such a packet, instead of doing their darnest to > deliver it, they drop it... > > There are some patches that help address the issue... > > Drivers should complain more loudly when a packet gets dropped by the > driver, since it is likely that the OS may retry the same packet, > just to have it fail, though sometimes it'll try a different set, and > it might go through, so all the user may notice is a slight lag if > they notice anything at all... > > -- > John-Mark Gurney Voice: +1 415 225 5579 > > "All that I will do, has been done, All that I have, has not." > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >