From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754654AbZCDJkK (ORCPT ); Wed, 4 Mar 2009 04:40:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752362AbZCDJjx (ORCPT ); Wed, 4 Mar 2009 04:39:53 -0500 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:35837 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750985AbZCDJjx (ORCPT ); Wed, 4 Mar 2009 04:39:53 -0500 Date: Wed, 04 Mar 2009 01:39:37 -0800 (PST) Message-Id: <20090304.013937.129768263.davem@davemloft.net> To: yanmin_zhang@linux.intel.com Cc: herbert@gondor.apana.org.au, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, jesse.brandeburg@intel.com, shemminger@vyatta.com Subject: Re: [RFC v1] hand off skb list to other cpu to submit to upper layer From: David Miller In-Reply-To: <1236158868.2567.93.camel@ymzhang> References: <1235546423.2604.556.camel@ymzhang> <20090224.233115.240823417.davem@davemloft.net> <1236158868.2567.93.camel@ymzhang> X-Mailer: Mew version 6.1 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Zhang, Yanmin" Date: Wed, 04 Mar 2009 17:27:48 +0800 > Both the new skb_record_rx_queue and current kernel have an > assumption on multi-queue. The assumption is it's best to send out > packets from the TX of the same number of queue like the one of RX > if the receved packets are related to the out packets. Or more > direct speaking is we need send packets on the same cpu on which we > receive them. The start point is that could reduce skb and data > cache miss. We have to use the same TX queue for all packets for the same connection flow (same src/dst IP address and ports) otherwise we introduce reordering. Herbert brought this up, now I have explicitly brought this up, and you cannot ignore this issue. You must not knowingly reorder packets, and using different TX queues for packets within the same flow does that.