Fedora xen - May 2007 - RE: Status of Xen on FC6 2.6.20.x - feedback

After 7 days of testing, I have found a potential instability with
Kernel-xen-2.6.20.2925 on FC6.   Symptom: machine spontaneously rebooted
upon launch of tvtime.  Previous launches of tvtime, 10+, were successful.
After reboot system was stable again (tvtime launched fine)

Nothing useful in xend.log, xend.debug.log, log/messages. 

Environment:  FC6, Intel Cor2, Hauppauge WinTV PCI, 4G Ram, WinXP Pro guest

Any suggestions on how to capture useful information if this happens again?



John Casey
 

-----Original Message-----
From: John Casey [mailto:john.a@Casey.net] 
Sent: Friday, May 25, 2007 11:32 AM
To: ''Daniel P. Berrange''
Cc: ''fedora-xen@redhat.com''
Subject: RE: [Fedora-xen] Status of Xen on FC6 2.6.20.x - feedback

I''ve been using Kernel-xen-2.6.20.2925 now since its release on the
21st on
an FC6 Intel Core2 machine, 4GB Ram, Sata Disks, tv card.  So far it seems
that all of the previous instability issues have been addressed.   I am also
running a WinXp pro guest, running since the 21st, and have had no
instability issues.

Thanks guys. 

John Casey
 

-----Original Message-----
From: Daniel P. Berrange [mailto:berrange@redhat.com] 
Sent: Monday, May 21, 2007 10:02 AM
To: John Casey
Cc: fedora-xen@redhat.com
Subject: Re: [Fedora-xen] Status of Xen on FC6 2.6.20.x

On Mon, May 21, 2007 at 05:55:47PM +0100, Daniel P. Berrange
wrote:
> On Mon, May 21, 2007 at 09:41:26AM -0700, John Casey wrote:
> > Can someone tell me or give me a pointer to the status of Xen on FC6
kernel
> > 2.6.20.x?    I''ve read about and experienced some serious
instability on
> > 2.6.20.x and was wondering when a stable release was expected.    All
of
the
> > threads I''ve read say to use Xen on 2.6.18, but since Xen is
not a
critical
> > requirement for me, I''d like to wait until it comes out on
2.6.20 (or
FC7)
> > which ever comes first.  
> 
> F7 is arriving real soon now and will be  Xen 3.1.0 + 2.6.20 kernel. This
> kernel will fix the 3 core kernel-xen bugs that are being experianced by
> most people (one 32-bit data corruption issue, 2 SMP bugs).
I should point out, this is all actually in rawhide right now....

kernel-xen-2.6.20-2925.8.fc7  + xen-3.1.0-0.rc7.2.fc7

And since rawhide is in deep freeze now it is in pretty good shape. This
is the rc7 pre-release, and we''ll update to the GA xen release very
shortly
after Fedora 7 is released. There''s no major changes missing there
really.
> We''re going to apply these same patches to the FC6 kernel-xen
which should
> also resolve the stability issues seen on the FC6 2.6.20 builds. I
don''t
> have an exact timeframe for this, but it should be in updates-testing at
> least fairly soon.

Dan.
-- 
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On Mon, 28 May 2007, John Casey wrote:
> After 7 days of testing, I have found a potential instability with
> Kernel-xen-2.6.20.2925 on FC6.   Symptom: machine spontaneously rebooted
> upon launch of tvtime.  Previous launches of tvtime, 10+, were successful.
> After reboot system was stable again (tvtime launched fine)
>
> Nothing useful in xend.log, xend.debug.log, log/messages.
>
> Environment:  FC6, Intel Cor2, Hauppauge WinTV PCI, 4G Ram, WinXP Pro guest
>
> Any suggestions on how to capture useful information if this happens again?
I have had similar experiences, however I found my problem. The machine is
overheating. With a non-xen kernel, I am seeing thermal throttling events in
syslog, but since xen does not support cpu frequency scaling, the cpu
actually overheats and the machine turns itself of before catching on fire.

The easiest way to track this is to use another machine with display to
login to the xen server and run:

while true; do sleep 1; sensors |grep Temp; done

When your xen machine reboots, you can see the last few temperature
measurements,
to see if you have the same problem.

With a non-xen kernel, I could set the maximum scaling frequency to the
minimum cpu freq (2.8Ghz) using /etc/cpuspeed.conf. But the machine still
overheated. Getting a new cooler didn''t help me either. Underclocking
in
the BIOS failed. And updating the BIOS didnt make a difference.

I would never see the /proc entries for the fans, so I couldn''t control
them. I know the fans can go faster, because when the machine boots,
before the OS loads, the fans blow like mad. But it seems I cannot set
them back in that mode from within Linux, so I''ve sort of written of
this machine now (Asus P5LD2-VM)

Paul