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 08:58:33 +0300 Message-ID: <51A6EA89.2070802@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> <1369854520.5109.79.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Willem de Bruijn , Or Gerlitz , e1000-devel@lists.sourceforge.net, netdev@vger.kernel.org, HPA , Jesse Brandeburg , Alex Rosenbaum , linux-kernel@vger.kernel.org, Eliezer Tamir , Andi Kleen , Eilon Greenstien , David Miller To: Eric Dumazet Return-path: In-Reply-To: <1369854520.5109.79.camel@edumazet-glaptop> 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 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? ------------------------------------------------------------------------------ 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