From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner+w=401wt.eu-S1763649AbYAaU4y@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1763649AbYAaU4y (ORCPT <rfc822;w@1wt.eu>);
	Thu, 31 Jan 2008 15:56:54 -0500
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754227AbYAaU4r
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Thu, 31 Jan 2008 15:56:47 -0500
Received: from ogre.sisk.pl ([217.79.144.158]:55365 "EHLO ogre.sisk.pl"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1753241AbYAaU4q (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Thu, 31 Jan 2008 15:56:46 -0500
From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [Regression] 2.6.24-git3: Major annoyance during suspend/hibernation on x86-64 (bisected)
Date: Thu, 31 Jan 2008 21:54:32 +0100
User-Agent: KMail/1.9.6 (enterprise 20070904.708012)
Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <srostedt@redhat.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>,
       Dmitry Adamushko <dmitry.adamushko@gmail.com>
References: <200801272229.48955.rjw@sisk.pl> <200801280226.22013.rjw@sisk.pl> <1201795128.32654.22.camel@lappy>
In-Reply-To: <1201795128.32654.22.camel@lappy>
MIME-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-15"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200801312154.33754.rjw@sisk.pl>
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thursday, 31 of January 2008, Peter Zijlstra wrote:
> 
> On Mon, 2008-01-28 at 02:26 +0100, Rafael J. Wysocki wrote:
> > On Sunday, 27 of January 2008, Ingo Molnar wrote:
> > > 
> > > * Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > > 
> > > > Hi,
> > > > 
> > > > 2.6.24-git3 adds a 5 - 10 sec delay to the suspend and hibernation 
> > > > code paths (probably related to the disabling of nonboot CPUs), which 
> > > > is !@#$%^&*() annoying.
> > > > 
> > > > It's 100% reproducible on my HP nx6325 and bisection idendified the 
> > > > following commit as the first bad one:
> > > > 
> > > > commit 764a9d6fe4b52995c8aba277e3634385699354f4
> > > > Author: Steven Rostedt <srostedt@redhat.com>
> > > > Date:   Fri Jan 25 21:08:04 2008 +0100
> > > > 
> > > >     sched: track highest prio task queued
> > > 
> > > hm, this patch is a NOP, so it's weird that it has an effect.
> > > 
> > > Do you have serial logging enabled perhaps? If the following WARN_ON() 
> > > triggers:
> > > 
> > > +               WARN_ON(p->prio < rq->rt.highest_prio);
> > > 
> > > then perhaps that can cause a 5-10 seconds delay. (that's how much time 
> > > it takes to printk a warning on the slowest serial settings)
> > > 
> > > but if you use suspend, then any such printks would be preserved in the 
> > > dmesg, right? If the WARN_ON() triggers, and if you remove it, do things 
> > > get faster?
> > 
> > No, this isn't the WARN_ON().
> > 
> > > this does have the feel of being scheduling related, but are you 
> > > absolutely sure about the precise identity of the patch?
> > 
> > Actually, not quite.  That's why I have verified it and found that another
> > patch is really responsible for the issue, namely:
> > 
> > commit 82a1fcb90287052aabfa235e7ffc693ea003fe69
> > Author: Ingo Molnar <mingo@elte.hu>
> > Date:   Fri Jan 25 21:08:02 2008 +0100
> > 
> >     softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks
> > 
> > Reverting this commit (it reverts with some minor modifications) fixes the
> > problem for me.
> 
> I can seem to reproduce this:
> 
> [root@opteron cpu1]# time echo 0 > online
> 
> real    0m6.230s
> user    0m0.000s
> sys     0m0.010s
> [root@opteron cpu1]# echo 1 > online
> [root@opteron cpu1]# time echo 0 > online
> 
> real    0m7.966s
> user    0m0.000s
> sys     0m0.011s
> 
> 
> I'll have a look at it.

Much appreciated, thanks!