From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: [PATCH] Disable TSO for non standard qdiscs Date: Thu, 31 Jan 2008 10:35:42 -0800 Message-ID: <47A214FE.3050200@hp.com> References: <20080131124632.GA25299@basil.nowhere.org> <47A212CB.1060403@hp.com> <20080131190326.GF4671@one.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, davem@davemloft.net To: Andi Kleen Return-path: Received: from g1t0029.austin.hp.com ([15.216.28.36]:37132 "EHLO g1t0029.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752514AbYAaSfo (ORCPT ); Thu, 31 Jan 2008 13:35:44 -0500 In-Reply-To: <20080131190326.GF4671@one.firstfloor.org> Sender: netdev-owner@vger.kernel.org List-ID: Andi Kleen wrote: > On Thu, Jan 31, 2008 at 10:26:19AM -0800, Rick Jones wrote: > >>Andi Kleen wrote: >> >>>TSO interacts badly with many queueing disciplines because they rely on >>>reordering packets from different streams and the large TSO packets can >>>make this difficult. This patch disables TSO for sockets that send over >>>devices with non standard queueing disciplines. That's anything but noop >>>or pfifo_fast and pfifo right now. >> >>Does this also imply that JumboFrames interacts badly with these qdiscs? >> Or IPoIB with its 65000ish byte MTU? > > > Correct. Of course it is always relative to the link speed. So if your > link is 10x faster and your packets 10x bigger you can get similarly > smooth shaping. So, at what timescale do people using these qdiscs expect things to appear "smooth?" 64KB of data at GbE speeds is something just north of half a millisecond unless I've botched my units somewhere. rick jones