From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH v10 net-next 0/6] net: low latency Ethernet device polling Date: Tue, 11 Jun 2013 00:32:44 -0700 Message-ID: <1370935964.3252.24.camel@edumazet-glaptop> References: <20130610083929.6955.87206.stgit@ladj378.jer.intel.com> <20130610.134116.1913599114372510768.davem@davemloft.net> <51B68AA6.1050105@linux.intel.com> <20130610.212443.1096102996038709384.davem@davemloft.net> <51B6C87B.70101@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: willemb@google.com, or.gerlitz@gmail.com, e1000-devel@lists.sourceforge.net, netdev@vger.kernel.org, hpa@zytor.com, amirv@mellanox.com, jesse.brandeburg@intel.com, eliezer@tamir.org.il, linux-kernel@vger.kernel.org, andi@firstfloor.org, bhutchings@solarflare.com, eilong@broadcom.com, David Miller To: Eliezer Tamir Return-path: In-Reply-To: <51B6C87B.70101@linux.intel.com> 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 Tue, 2013-06-11 at 09:49 +0300, Eliezer Tamir wrote: > I would like to hear opinions on what needs to be added to make this > feature complete. > > The list I have so far is: > 1. add a socket option Yes, please. I do not believe all sockets on the machine are candidate for low latency. In fact very few of them should be, depending on the number of cpu and/or RX queues. > 2. support for poll/select As long as the cost of llpoll is bounded per poll()/select() call it will be ok. > 3. support for epoll For this one, I honestly do not know how to proceed. epoll Edge Trigger model is driven by the wakeups events. The wakeups come from frames being delivered by the NIC (for UDP/TCP sockets) If epoll_wait() has to scan the list of epitem to be able to perform the llpoll callback, it will be too slow : We come back to poll() model, with O(N) execution time. Ideally we would have to callback llpoll not from the tcp_poll(), but right before putting current thread in wait mode. > > Also, would you accept a trailing whitespace cleanup patch for > fs/select.c? This has to be submitted to lkml ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ 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