From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: [PATCH net-2.6] Re: rib_trie / Fix inflate_threshold_root. Now=15 size=11 bits Date: Thu, 2 Jul 2009 21:06:26 +0200 Message-ID: <20090702190626.GA2737@ami.dom.local> References: <20090701063651.GA4876@ff.dom.local> <20090701072409.GA12592@ff.dom.local> <4A4B2FA8.3040007@itcare.pl> <20090701101333.GB12715@ff.dom.local> <20090701110407.GC12715@ff.dom.local> <4A4BE06F.3090608@itcare.pl> <20090702053216.GA4954@ff.dom.local> <4A4C48FD.7040002@itcare.pl> <20090702060011.GB4954@ff.dom.local> <19020.53998.330803.83554@gargle.gargle.HOWL> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: =?iso-8859-2?Q?Pawe=B3?= Staszewski , Linux Network Development list , Robert Olsson To: Robert Olsson Return-path: Received: from mail-bw0-f225.google.com ([209.85.218.225]:45263 "EHLO mail-bw0-f225.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750946AbZGBTGs (ORCPT ); Thu, 2 Jul 2009 15:06:48 -0400 Received: by bwz25 with SMTP id 25so1423511bwz.37 for ; Thu, 02 Jul 2009 12:06:50 -0700 (PDT) Content-Disposition: inline In-Reply-To: <19020.53998.330803.83554@gargle.gargle.HOWL> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Jul 02, 2009 at 05:31:58PM +0200, Robert Olsson wrote: > > Jarek Poplawski writes: > > > Yes, it looks like we can't free memory so simple because of such huge > > latencies. > > Controlling RCU seems crucial. Insertion of the full BGP table increased > from 2 seconds to > 20 min with one synchronize_rcu patches. I wish I knew this a few days before. I could imagine a slow down, but it looked like it was stuck. Since these last changes weren't tested on SMP + PREEMPT I thought there is still something broken. (I was mainly interested in this synchronize_rcu at the moment as a preemption test.) > And fib_trie "worst case" wrt memory is the root node. So maybe we should > monitor changes in root node and use this to control synchronize_rcu. > > Didn't Paul suggest something like this? Sure, and it needs testing, but we should send some safe preemption fix for -stable first, don't we? > And with don't find any decent solution we have to add an option for > a fixed and pre-allocated root-nod typically for BGP-routers. Probably you're right; I'd prefer to see the test results showing a difference vs. simply less aggressive root thresholds. But of course, even if not convinced, I'll respect your choice as the author and maintainer, so feel free to NAK my proposals - I won't get it personally.;-) Cheers, Jarek P.