From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH] IPROUTE: Modify tc for new PRIO multiqueue behavior Date: Fri, 4 May 2007 13:01:10 -0700 Message-ID: <20070504130110.0694aee6@freekitty> References: <1178109829.4074.48.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: , "Patrick McHardy" , , , "cramerj" , "Kok, Auke-jan H" , "Leech, Christopher" , To: "Waskiewicz Jr, Peter P" Return-path: Received: from smtp.osdl.org ([65.172.181.24]:45912 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422808AbXEDUGk (ORCPT ); Fri, 4 May 2007 16:06:40 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, 3 May 2007 14:03:07 -0700 "Waskiewicz Jr, Peter P" wrote: > > Lets come up with some terminology; lets call multiqueue what > > the qdiscs do; lets call what the NICs do multi-ring. > > Note, i have thus far said you need to have both and they > > must be in sync. > > I agree with the terminology. > > > This maybe _the_ main difference we have in opinion. > > Like i said earlier, I used to hold the same thoughts you do. > > And i think you should challenge my assertion that it doesnt > > matter if you have a single entry point; [my assumptions are > > back in what i called #b and #c]. > > Here is a paper that describes what exactly we're trying to do: > http://www.ieee802.org/3/ar/public/0503/wadekar_1_0503.pdf. Basically > we need the ability to pause a queue independantly of another queue. > Because of this requirement, the kernel needs visibility into the driver > and to have knowledge of and provide control of each queue. Please note > that the API I'm proposing is a generic representation of the Datacenter > Ethernet mentioned in the paper; I figured if we're putting in an > interface to support it, it should be generic so other technologies out > there could easily use it. > Just because they want to standardize, and put it in hardware doesn't mean it is a good idea and Linux needs to support it! Why is it better for hardware to make the "next packet to send" decision? For wired ethernet, I can't see how adding the complexity of fixed number of small queues is a gain. Better to just do the priority decision in software and then queue it to the hardware. This seems like the old Token Ring and MAP/TOP style crap crammed on top of Ethernet. -- Stephen Hemminger