linux-kernel - Re: [Regression] 2.6.24-git3: Major annoyance during suspend/hibernation on x86-64 (bisected)

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Date:	Mon, 28 Jan 2008 11:46:22 -0500
From:	Steven Rostedt <srostedt@...hat.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
CC:	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Dmitry Adamushko <dmitry.adamushko@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [Regression] 2.6.24-git3: Major annoyance during suspend/hibernation
 on x86-64 (bisected)

Rafael J. Wysocki wrote:
> On Monday, 28 of January 2008, Rafael J. Wysocki wrote:
>> On Monday, 28 of January 2008, Steven Rostedt wrote:
>>> Rafael J. Wysocki wrote:
>>>
>>>> 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@...e.hu>
>>>> Date:   Fri Jan 25 21:08:02 2008 +0100
>>>>
>>>>     softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks
>>> Are you getting a bunch of prints from the softlockup detector in dmesg?
>> No, I don't.  In fact, I don't get _any_ messages from it whatsoever.
>>
>>> I wonder if the detector can detect a long timeout caused by suspend and 
>>> resume and if not is triggering false positives?
>> I'm not sure, but the code is supposed to be suspend-aware, IIRC.  However,
>> I'm seeing a similar symptom on poweroff on an SMP x86-64 box, so it may be
>> more directly related to the CPU hotplug.  I'll try to verify that.
> 
> As I expected, the delay is also observable when I do:
> 
> echo 0 > /sys/devices/system/cpu/cpu1/online
> 
> (it's variable, between 3 and 30 seconds).  Again, no messages appear in dmesg
> when this happens.
> 
> I suspect I'll be able to reproduce it on another x86-64 SMP machine (I'm going
> to try that later today).

Could you download my tracing patches from here:

 
http://people.redhat.com/srostedt/tracing/mcount-tracing-patches-v6.tar.bz2

Apply the above patches and select all but the histogram tracers. Then 
run this program

   http://people.redhat.com/srostedt/tracing/trace-cmd.c

  ./trace-cmd -f echo 0 > /sys/devices/system/cpu/cpu1/online

then do this (mount debugfs):

   bzip2 -c /debugfs/tracing/latency_trace > /tmp/trace.bz2

and send the result to myself and Ingo.

Thanks,

-- Steve

> 
> Thanks,
> Rafael

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