From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751782AbWFVMrD (ORCPT ); Thu, 22 Jun 2006 08:47:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751783AbWFVMrD (ORCPT ); Thu, 22 Jun 2006 08:47:03 -0400 Received: from web33314.mail.mud.yahoo.com ([68.142.206.129]:29108 "HELO web33314.mail.mud.yahoo.com") by vger.kernel.org with SMTP id S1751782AbWFVMrC (ORCPT ); Thu, 22 Jun 2006 08:47:02 -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=ucdLxYUVnqS1HQ1VtbUcuI3Q+z7JvTKxOlufYtvfZVRE36b4/QtL1w/mxbeykfyMVV83GxtOQ7JiVLgWyeMtXzTPo7U+WBpS2p+L342dwu0NfHWpimeKQG0rUSWVvYrMgL04L1Hfq94T4IPuI7i7buM5JvMELOxm7MggqVscHdU= ; Message-ID: <20060622124700.4700.qmail@web33314.mail.mud.yahoo.com> Date: Thu, 22 Jun 2006 05:47:00 -0700 (PDT) From: Danial Thom Reply-To: danial_thom@yahoo.com Subject: Re: Dropping Packets in 2.6.17 To: Arjan van de Ven Cc: linux-kernel@vger.kernel.org In-Reply-To: <1150977316.3120.26.camel@laptopd505.fenrus.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --- Arjan van de Ven wrote: > On Thu, 2006-06-22 at 04:31 -0700, 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? > > Hi Danial, > > the most likely tunable that will help you is > > /proc/sys/vm/min_free_kbytes > > For the router kind of device that one usually > needs bumping a bit; > without the bumping the VM doesn't see enough > "normal" activity to tune > it's emergency/interrupt handling buffers (and > most networking > allocations happen in interrupt context), and > then ends up failing > allocations in interrupt context, which leads > to dropped packets. I don't think thats the problem, as I've tracked the problem to packets being dropped because of excessive backlog (ie, they are being dropped gracefully). However with a backlog of 20000, and a traffic level of about 75,000pps, that means almost 1/3 of a second that the system doesn't process packets, which is just unacceptable. I'll try changing the setting, but running out of memory doesn't seem to be the issue. I think what I need is some mechanism to make interrupts a priority, like it was back in the days when networking was more important then mp3 playback. Danial __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com