From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161081AbWFVLzT (ORCPT ); Thu, 22 Jun 2006 07:55:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161088AbWFVLzT (ORCPT ); Thu, 22 Jun 2006 07:55:19 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:29410 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S1161089AbWFVLzS (ORCPT ); Thu, 22 Jun 2006 07:55:18 -0400 Subject: Re: Dropping Packets in 2.6.17 From: Arjan van de Ven To: danial_thom@yahoo.com Cc: linux-kernel@vger.kernel.org In-Reply-To: <20060622113147.3496.qmail@web33304.mail.mud.yahoo.com> References: <20060622113147.3496.qmail@web33304.mail.mud.yahoo.com> Content-Type: text/plain Date: Thu, 22 Jun 2006 13:55:16 +0200 Message-Id: <1150977316.3120.26.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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. Greetings, Arjan van de Ven