Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967531Ab3E3F6r (ORCPT ); Thu, 30 May 2013 01:58:47 -0400 Received: from mga09.intel.com ([134.134.136.24]:55164 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751488Ab3E3F6i (ORCPT ); Thu, 30 May 2013 01:58:38 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,768,1363158000"; d="scan'208";a="321750086" Message-ID: <51A6EA89.2070802@linux.intel.com> Date: Thu, 30 May 2013 08:58:33 +0300 From: Eliezer Tamir User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130509 Thunderbird/17.0.6 MIME-Version: 1.0 To: Eric Dumazet CC: Or Gerlitz , David Miller , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Jesse Brandeburg , Don Skidmore , e1000-devel@lists.sourceforge.net, Willem de Bruijn , Andi Kleen , HPA , Eilon Greenstien , Alex Rosenbaum , Eliezer Tamir Subject: Re: [PATCH v6 net-next 2/5] net: implement support for low latency socket polling References: <20130529063916.27486.3841.stgit@ladj378.jer.intel.com> <20130529063935.27486.18610.stgit@ladj378.jer.intel.com> <51A617D7.6000406@linux.intel.com> <1369854520.5109.79.camel@edumazet-glaptop> In-Reply-To: <1369854520.5109.79.camel@edumazet-glaptop> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1456 Lines: 34 On 29/05/2013 22:08, Eric Dumazet wrote: > On Wed, 2013-05-29 at 21:52 +0300, Or Gerlitz wrote: >> Eliezer Tamir wrote: >>> Or Gerlitz wrote: >> >>>> Unlike with TCP sockets, UDP sockets may receive packets from multiple >>>> sources and hence the receiving context may be steered to be executed >>>> on different cores through RSS or other Flow-Steering HW mechanisms >>>> which could mean different napi contexts for the same socket, is that >>>> a problem here? what's the severity? >> >>> Nothing will break if you poll on the wrong queue. >>> Your data will come through normal NAPI processing of the right queue. >> >> Can you elaborate a little further, why you call this "wrong" and "right"? >> -- > > This definitely need some documentation, because before llpoll, device > RX path was serviced by the cpu receiving the harwdare interrupt. > > So the "wrong" queue could add false sharing, and wrong NUMA > allocations. Yes, To work properly when you have more than one NUMA node, you have to have packet steering set up, either by your NIC or by HW accelerated RFS. I would like to add a short writeup of the design and suggested configuration. Where should it go? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/