From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751810AbWFVPD7 (ORCPT ); Thu, 22 Jun 2006 11:03:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751804AbWFVPD7 (ORCPT ); Thu, 22 Jun 2006 11:03:59 -0400 Received: from web33302.mail.mud.yahoo.com ([68.142.206.117]:59261 "HELO web33302.mail.mud.yahoo.com") by vger.kernel.org with SMTP id S1751813AbWFVPD7 (ORCPT ); Thu, 22 Jun 2006 11:03:59 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:Received:Date:From:Reply-To:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=vzL4/Lj7mSUnBQWSl/YP/CglS5jN6YlrPgkYncY7cV2tDKHPW1CwPF7Dj54Q+AlLSIzx5089pQPp/keYwrsIh7T6A8BnwvzTa2PTVjOWYyzAXAelKP7FpQV10Vpq/X0tbseEawFnKDjSAQoiiOWCWT1V7xeQdAY2m6iKXh8nGZs= ; Message-ID: <20060622150357.37194.qmail@web33302.mail.mud.yahoo.com> Date: Thu, 22 Jun 2006 08:03:57 -0700 (PDT) From: Danial Thom Reply-To: danial_thom@yahoo.com Subject: Re: Dropping Packets in 2.6.17 To: =?ISO-8859-1?Q?=20=22P=E1draig=22?= Brady Cc: linux-kernel@vger.kernel.org In-Reply-To: <449A9ADC.9070800@draigBrady.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --- Pádraig Brady wrote: > Danial Thom wrote: > > I'm trying to make a case for using linux as > a > > network appliance, but I can't find any > > combination of settings that will keep it > from > > dropping packets at an unacceptably high > rate. > > The test system is a 1.8Ghz Opteron with > intel > > gigE cards running 2.6.17. I'm passing about > 70K > > pps through the box, which is a light load, > but > > userland activities (such as building a > kernel) > > cause it to lose packets, even with backlog > set > > to 20000. I had the same problem with 2.6.12 > and > > abandoned the effort. Has anything been done > > since to give priority to networking? You > can't > > have a network appliance drop packets when > some > > application is gathering stats or a user is > > looking at a graph. What tunings are > available? > > For reference with 2.4.20 on a dual 3.4GHz xeon > and 2 x e1000 cards, I was able to capture, > classify > and do sophisticated statistical calculations > on > 625Kpps per interface (1.3 million packets per > second). > The bottleneck at this point was memory > bandwidth. > Allowing some drops the average rate went up to > the > PCI bottleneck of about 850kpps/port. > Classification and Computation was done in > userspace. > > Note there is a max interrupt rate of around > 80K/s > on x86 at least (not sure about opteron), so > make > sure you're using NAPI. /proc/interrupts will > show your interrupt rate. > > If the packets go to userspace, make sure > you're using > CONFIG_PACKET_MMAP Unfortunately I can do that much with FreeBSD 4.x with 1 2.0Ghz opteron, so its not a very compelling case to have to spend twice as much on hardware to use LINUX. However 2.4 seemed much better than 2.6 in this regard. 2.6 wants to drop a lot more packets. The goal of using 2.6 is to utilize DP better, but it obviously has to perform better than a UP Freebsd box. What ITR setting are using for the e1000 driver? ># Lots of kernel memory needed for e1000 >vm.min_free_kbytes = 65535 I'm curious as to why a vm setting is useful, as it doesn't seem that the e1000 driver uses virtual memory? Since rings are replenished with sk_buffs, and sk_buffs have to be contiguous, how does vm come into play? DT __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com