From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [ofa-general] Re: [PATCH 2/3][NET_BATCH] net core use batching Date: Tue, 9 Oct 2007 20:30:27 +0200 Message-ID: <20071009183027.GA552@one.firstfloor.org> References: <1191886845.4373.138.camel@localhost> <470AD5D7.1070000@garzik.org> <20071008.184126.124062865.davem@davemloft.net> <20071009112225.5f9756e7@freepuppy.rosehill> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andi Kleen , David Miller , jeff@garzik.org, johnpol@2ka.mipt.ru, herbert@gondor.apana.org.au, gaagaan@gmail.com, Robert.Olsson@data.slu.se, netdev@vger.kernel.org, rdreier@cisco.com, peter.p.waskiewicz.jr@intel.com, hadi@cyberus.ca, mcarlson@broadcom.com, jagana@us.ibm.com, general@lists.openfabrics.org, mchan@broadcom.com, tgraf@suug.ch, randy.dunlap@oracle.com, sri@us.ibm.com, kaber@trash.net To: Stephen Hemminger Return-path: Received: from one.firstfloor.org ([213.235.205.2]:39166 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751371AbXJISaa (ORCPT ); Tue, 9 Oct 2007 14:30:30 -0400 Content-Disposition: inline In-Reply-To: <20071009112225.5f9756e7@freepuppy.rosehill> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org > I wonder about the whole idea of queueing in general at such high speeds. > Given the normal bi-modal distribution of packets, and the predominance > of 1500 byte MTU; does it make sense to even have any queueing in software > at all? Yes that is my point -- it should just pass it through directly and the driver can then put it into the different per CPU (or per whatever) queues managed by the hardware. The only thing the qdisc needs to do is to set some bit that says "it is ok to put this into difference queues; don't need strict ordering" Otherwise if the drivers did that unconditionally they might cause problems with other qdiscs. This would also require that the driver exports some hint to the upper layer on how large its internal queues are. A device with a short queue would still require pfifo_fast. Long queue devices could just pass through. That again could be a single flag. -Andi