From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966309AbYD1SxO (ORCPT ); Mon, 28 Apr 2008 14:53:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965964AbYD1Swz (ORCPT ); Mon, 28 Apr 2008 14:52:55 -0400 Received: from relay2.sgi.com ([192.48.171.30]:38241 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965948AbYD1Swy (ORCPT ); Mon, 28 Apr 2008 14:52:54 -0400 Date: Mon, 28 Apr 2008 13:52:52 -0500 From: Dimitri Sivanich To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Peter Zijlstra Subject: Re: [PATCH] disable softlockup detection at boottime Message-ID: <20080428185252.GC1167@sgi.com> References: <20080423201613.GA8546@sgi.com> <20080428165544.GE18210@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080428165544.GE18210@elte.hu> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 28, 2008 at 06:55:44PM +0200, Ingo Molnar wrote: > > good idea - but why dont you set softlockup_thresh to 0, which is the > "off" switch already? (and that way it can be turned back on later as > well, by the sysadmin.) > I'm getting unaligned access errors trying to set it to anything, so it's not working for me currently (2.6.25): It's tripping up on the address of 'one', which is an int that is not properly aligned for the unsigned long comparison in proc_doulongvec_minmax on my 64 bit machine. Also, the value '0' is invalid for softlockup_thresh, correct? I temporarily got around these issues with the following hack. Index: linux/kernel/sysctl.c =================================================================== --- linux.orig/kernel/sysctl.c 2008-04-16 21:49:44.000000000 -0500 +++ linux/kernel/sysctl.c 2008-04-28 13:37:43.000561710 -0500 @@ -748,9 +748,9 @@ static struct ctl_table kern_table[] = { .data = &softlockup_thresh, .maxlen = sizeof(unsigned long), .mode = 0644, - .proc_handler = &proc_doulongvec_minmax, + .proc_handler = &proc_dointvec_minmax, .strategy = &sysctl_intvec, - .extra1 = &one, + .extra1 = &zero, .extra2 = &sixty, Also, I'm not convinced that changing this to 0 does indeed switch off softlockup detection (but I could be missing something): void softlockup_tick(void) { .. .. /* Warn about unreasonable delays: */ if (now <= (touch_timestamp + softlockup_thresh)) return; per_cpu(print_timestamp, this_cpu) = touch_timestamp; spin_lock(&print_lock); printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n", this_cpu, now - touch_timestamp, current->comm, task_pid_nr(current)); Dimitri