From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758650AbYG3HV1 (ORCPT ); Wed, 30 Jul 2008 03:21:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752355AbYG3HVS (ORCPT ); Wed, 30 Jul 2008 03:21:18 -0400 Received: from casper.infradead.org ([85.118.1.10]:38461 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751559AbYG3HVS (ORCPT ); Wed, 30 Jul 2008 03:21:18 -0400 Subject: Re: combinatorial explosion in lockdep From: Peter Zijlstra To: David Miller Cc: mingo@elte.hu, linux-kernel@vger.kernel.org In-Reply-To: <20080729.235623.211977761.davem@davemloft.net> References: <20080728235133.GA7956@elte.hu> <20080728.174415.154327359.davem@davemloft.net> <20080729.214503.126934382.davem@davemloft.net> <20080729.235623.211977761.davem@davemloft.net> Content-Type: text/plain Date: Wed, 30 Jul 2008 09:21:07 +0200 Message-Id: <1217402467.6364.9.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2008-07-29 at 23:56 -0700, David Miller wrote: > From: David Miller > Date: Tue, 29 Jul 2008 21:45:03 -0700 (PDT) > > > If we can agree on this as a fix, it should definitely be backported > > and submitted for -stable :-) > > > > ---------------------------------------- > > > > lockdep: Fix combinatorial explosion in lock subgraph traversal. > > So the next problem I run into is that 8192 is not a large > enough MAX_LOCKDEP_ENTRIES for this larger cpu count boxes. > 8192 isn't even big enough for my 64 cpu box. > > It needs to be scaled by NR_CPUS, or something like that. Or something like that indeed - if distro kernels are going to be build using NR_CPUS=4096, then these tables might explode - then again, lockdep is only enabled on -debug kernels anyway... So yeah.