Date:	Fri, 4 Apr 2008 16:32:32 +0100
From:	Ken Moffat <zarniwhoop@...world.com>
To:	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>
Cc:	Ingo Molnar <mingo@...e.hu>, "Rafael J. Wysocki" <rjw@...k.pl>,
	lkml <linux-kernel@...r.kernel.org>, a.p.zijlstra@...llo.nl,
	aneesh.kumar@...ux.vnet.ibm.com, dhaval@...ux.vnet.ibm.com,
	Balbir Singh <balbir@...ibm.com>, skumar@...ux.vnet.ibm.com
Subject: Re: Regression in gdm-2.18 since 2.6.24

On Fri, Apr 04, 2008 at 08:07:01PM +0530, Srivatsa Vaddagiri wrote:
> On Thu, Apr 03, 2008 at 08:19:16PM +0100, Ken Moffat wrote:
> >  Next I went forward to 2.6.25-rc8.  Here, I found that 'patch'
> > would not revert the first hunk of that attachment because of a
> > context change.  So, I tried reverting only the second hunk (I didn't
> > know why it had been changed, so maybe they were to fix different
> > problems) - interestingly, that passed all 5 attempts to restart,
> > and failed all 5 attempts to shutdown.  I then tried the second
> > attachment (which reverts both hunks from rc8) and all of my tests
> > passed.
> 
> Just to confirm, are you saying you applied patch below on top of
> 2.6.25-rc8 and it solved your shutdown issues?
> 
 Yes.  But, from your later comments I wonder if my description is
insufficiently clear:  the loss of functionality appears to be wholly
within gdm - that is, it's login window, and the confirm dialog
disappear but the background remains (covering all the screen) and
gdm is still running.  I switch to a tty (as I've done now) and I
can then reboot, or shutdown as the root user.

 Meanwhile, top shows two instances of gdm-binary and Xorg are still
running - I assume the two instances are normal.
> 
> ---
>  kernel/sched_fair.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> Index: current/kernel/sched_fair.c
> ===================================================================
> --- current.orig/kernel/sched_fair.c
> +++ current/kernel/sched_fair.c
> @@ -510,7 +510,7 @@
>  
>  	if (!initial) {
>  		/* sleeps upto a single latency don't count. */
> -		if (sched_feat(NEW_FAIR_SLEEPERS)) {
> +		if (sched_feat(NEW_FAIR_SLEEPERS) && entity_is_task(se)) {
>  			vruntime -= calc_delta_fair(sysctl_sched_latency,
>  						    &cfs_rq->load);
>  		}
> @@ -1145,7 +1145,7 @@
>  	 * More easily preempt - nice tasks, while not making
>  	 * it harder for + nice tasks.
>  	 */
> -	if (unlikely(se->load.weight > NICE_0_LOAD))

> +	if (unlikely(se->load.weight != NICE_0_LOAD))
>  		gran = calc_delta_fair(gran, &se->load);
>  
>  	if (pse->vruntime + gran < se->vruntime)
> 
> 
> The (reverse of above) patch was required to solve latency issues reported by
> several folks (ex: http://ozlabs.org/pipermail/linuxppc-dev/2008-January/050355.html ).
> 
> I don't see any obvious reason why this patch affects shutdown. Is there
> any way you can get more debug data? Basically when the machine enters
> into problem state, I want to see dmesg, /proc/sched_debug output and Sysrq-T
> o/p. You could get this by logging into the system over network or (if n/w
> is not working in that state) by running this script:
> 
> [First ensure that syslogd is capturing kernel messages in
> /var/log/messages:
> 
> Edit /etc/syslog.conf to ensure it has this line uncommented:
> 
> kern.*          /var/log/messages
> 
> Restart syslog after any changes
> ]
> 
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> 
> #!/bin/bash
> 
> /etc/init.d syslog stop
> mv /var/log/messages /var/log/messages.old.$$
> touch /var/log/messages
> /etc/init.d syslog start
> 
> <Initiate Gnome shutdown thr' command line interface> &
> 
> sleep 10
> echo "Process List" 	> /tmp/sched-log
> ps -elf 		>> /tmp/sched-log
> echo 			>> /tmp/sched-log
> echo "Sched debug"	>> /tmp/sched-log
> cat /proc/sched_debug 	>> /tmp/sched-log
> echo "Process stack trace" >> /tmp/sched-log
> echo 1 > /proc/sys/kernel/sysrq
> echo t > /proc/sysrq-trigger 
> 
> echo "dmesg output"	>> /tmp/sched-log
> cat /var/log/messages 	>> /tmp/sched-log
> 
> 
> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
> 
> sched-log file size would be large. You could send it to me privately or
> host it on a website and send a pointer to it.
> 
> - vatsa

 For the first attempt, I've kept to my old logging (kernel messages
in kern.log, generality in sys.log), so I've put both there.  This
is done manually (I don't have a mouse in the tty to copy the
script).  Log was about 200K, but after gzipping, it reduces to 18K
so I'll attach it.  This is a number of minutes after I tried to
shutdown from gdm (time to login on a tty, ssh to where the mail is,
and then start replying).

 I don't quite understand the 'Gnome shutdown through command line'
part, and perhaps I don't have that part of gnome compiled (I only
have what I need for the applets and applications that I use).  If
it's important, please specify in detail how you want me to
shutdown.

 If for some reason this log doesn't suit you, I'll copy your script
and do it all exactly.

Ken
-- 
das eine Mal als Tragödie, das andere Mal als Farce

Download attachment "sched-log.gz" of type "application/x-gunzip" (17757 bytes)

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