Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1767680AbXEDFac (ORCPT ); Fri, 4 May 2007 01:30:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1767692AbXEDFac (ORCPT ); Fri, 4 May 2007 01:30:32 -0400 Received: from 1wt.eu ([62.212.114.60]:2486 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1767680AbXEDFab (ORCPT ); Fri, 4 May 2007 01:30:31 -0400 Date: Fri, 4 May 2007 07:30:27 +0200 From: Willy Tarreau To: =?iso-8859-1?Q?=D8yvind_V=E5gen_J=E6gtnes?= Cc: linux-kernel@vger.kernel.org Subject: Re: Routing 600+ vlan's via linux problems (looks like arp problems) Message-ID: <20070504053027.GA32604@1wt.eu> References: <20070503205341.GB943@1wt.eu> <20070503222334.GD943@1wt.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2650 Lines: 72 On Fri, May 04, 2007 at 05:48:18AM +0200, ?yvind V?gen J?gtnes wrote: > Hi again :) > > On 5/4/07, Willy Tarreau wrote: > >On Thu, May 03, 2007 at 11:12:09PM +0200, ?yvind V?gen J?gtnes wrote: > >> On 5/3/07, Jan Engelhardt wrote: > >> > > >> >On May 3 2007 22:53, Willy Tarreau wrote: > >> >>> For the rest all we see in the arp cache is (incomplete) > >> >> > >> >>I suspect that your arp cache is full (128 entries by default). > >> >>Check /proc/sys/net/ipv4/neigh/gc_thresh1 (128 for me). You can > >> >>set it as high as gc_thresh2 (512 for me), and I don't know what > >> >>happens above. > >> > > >> >Above, you will perhaps need the not-so-elegant userspace arpd :-/ > >> > >> Yes, i was suspecting that the arp cache got full, but i will try > >> increasing it :) > >> Would there be any huge bugs if i change these lines in arp.c: > >> > >> .gc_thresh1 = 128, > >> .gc_thresh2 = 512, > >> > >> to > >> > >> .gc_thresh1 = 700, > >> .gc_thresh2 = 700, > >> > >> under the definition for struct arp_tbl? > > > >I don't think it could cause a problem, but network people will surely > >correct me if I'm wrong. > > System is up and running perfectly now, it is routing everything at > about 200 mbps now with only 5% load avg with the above changes to > arp.c > > So the real question now is, why is this number so low by default? > It would probably be much better if this could be handled dynamically > in the kernel. I remember I read an argument against this a long time ago, but I don't remember where. I think it was some arbitrary decision that people using more than X ARP entries will need arpd. Most probably the code path in the ARP updates is/was not much optimized to handle large number of entries. Think about cable operators who may have 10-20000 entries ! > Its a Juniper M7i > It comes default with a 5400 rpm laptop 2.5" harddrive but now we > bought a more robust "server" 2.5" harddrive. The "server" ones are not necessarily more robust, often they are faster. > It still barfs on the OS > install, so the linux is doing all the job now. Will get a juniper guy > to come and fix :) > > As a side note, i'm starting to wonder if it was worth the $20k when i > could just have a linux machine to do the job with a clone for backup > ;) That's often how linux penetrates the enterprise ;-) Willy - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/