linux-kernel - Re: Clock has stopped (time/date looping over 5 seconds), things are

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Date:	Sat, 05 Apr 2008 02:50:47 +0200
From:	devzero@....de
To:	rogerheflin@...il.com
Cc:	dan.hecht@...are.com, johnstul@...ibm.com,
	linux-kernel@...r.kernel.org, zippel@...ux-m68k.org
Subject: Re: Clock has stopped (time/date looping over 5 seconds), things are

so, this happens on real hardware for you?

i could reproduce this with a linux virtual machine on vmware - whenever i suspended the windows host with a linux vm running in vmware, after resume the linux vm showed exactly this issue.
after some investigation i found, that it would recover from that state after some time - and the time needed for recover was (more or less) proportional to that time the host was in suspend(hibernate) state.

also see http://marc.info/?l=linux-kernel&m=120186717701371&w=2

i thought that was vmware related and i gave a bug report to dan hecht - i didn`t hear anything since then, but i think it`s worth CC`ing him.

not sure if 
[PATCH 1/2] Introduce clocksource_forward_now -> http://marc.info/?l=linux-kernel&m=120716471203567&w=2
[PATCH 2/2] Introduce CLOCK_MONOTONIC_RAW -> http://marc.info/?l=linux-kernel&m=120596518521892&w=2 
is related ? (also CC`d the patch authors, they will probably know)

regards
roland

List:       linux-kernel
Subject:    Clock has stopped (time/date looping over 5 seconds), things are
From:       Roger Heflin <rogerheflin () gmail ! com>
Date:       2008-04-04 21:27:11
Message-ID: 47F69D2F.8010607 () gmail ! com
[Download message RAW]

So far what I have is that the clock is moving between
10:01:03 to 10:01:07 (when it gets to 07 it goes back to 03), doing rdate -s
results in things changing:

16:12:38 to 16:12:43 (resets back to :38).

Doing this:
while true ; do date; usleep 1000000; done
Fri Apr  4 16:12:39 CDT 2008
Fri Apr  4 16:12:40 CDT 2008
Fri Apr  4 16:12:41 CDT 2008
Fri Apr  4 16:12:42 CDT 2008
Fri Apr  4 16:12:43 CDT 2008

It stops at :43, ^C is required, and you can then restart it with repeatable 
results.

This F7 - 2.6.23.15-80.fc7

dmesg/messages contain nothing abnormal.

This machine has done it several times, a freqency of maybe 1x per every couple 
of weeks or so.   I believe it had also done this with: 2.6.22.9-91.fc7 so it
has been doing this for a while.   It used to work with some older kernel (I 
don't know which).

Given what the clock is doing, things that sleep at the wrong time hang forever, 
and a number of other things fail to work.

vmstat 1 results in a single line being printed out, and then a floating point 
exception.

"shutdown -r now" fails to complete, power cycle is required to get the machine
back up.

I don't believe any hardware failure that I can think of would cause the clock 
to do what mine is doing.

Ideas?

                                Roger
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