From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eliezer Tamir Subject: Re: [PATCH v6 net-next 2/5] net: implement support for low latency socket polling Date: Thu, 30 May 2013 09:04:18 +0300 Message-ID: <51A6EBE2.6050108@linux.intel.com> References: <20130529063916.27486.3841.stgit@ladj378.jer.intel.com> <20130529063935.27486.18610.stgit@ladj378.jer.intel.com> <51A617D7.6000406@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Willem de Bruijn , e1000-devel@lists.sourceforge.net, netdev@vger.kernel.org, HPA , Jesse Brandeburg , Alex Rosenbaum , linux-kernel@vger.kernel.org, Eliezer Tamir , Andi Kleen , Eric Dumazet , Eilon Greenstien , David Miller To: Or Gerlitz Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: e1000-devel-bounces@lists.sourceforge.net List-Id: netdev.vger.kernel.org On 29/05/2013 21:52, 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"? Right == the queue the packets arrive on. Wrong == any other queue. BTW, if you have an application that receives UDP data to an unbound socket, wouldn't it be better in any case to steer all of the incoming packets for this UDP socket to a single queue disregarding the source address? (Can't your hardware do that?) The general approach is that userspace needs to make sure that threads, connections and IRQs are bound to the right CPUs. -Eliezer ------------------------------------------------------------------------------ Introducing AppDynamics Lite, a free troubleshooting tool for Java/.NET Get 100% visibility into your production application - at no cost. Code-level diagnostics for performance bottlenecks with <2% overhead Download for free and get started troubleshooting in minutes. http://p.sf.net/sfu/appdyn_d2d_ap1 _______________________________________________ E1000-devel mailing list E1000-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/e1000-devel To learn more about Intel® Ethernet, visit http://communities.intel.com/community/wired