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AW: RE: [Xen-devel] Huge Time went backwards

To: "dan.magenheimer" <dan.magenheimer@xxxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: AW: RE: [Xen-devel] Huge Time went backwards
From: "Carsten Schiers" <carsten@xxxxxxxxxx>
Date: Fri, 3 Apr 2009 19:10:40 +0200
Cc: "Tim.Deegan" <Tim.Deegan@xxxxxxxxxx>
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> Interesting.  This is reported booting dom0, correct?  Are
> you running NTP in dom0?

It's in Dom0 log when powernow-k8 is loaded, which is after loading loop 
and prior on 
mounting disks. Roughly 4 seconds prior to starting ntpd, so I guess it 
has no interaction.

It feels a bit like that 3.3.1 and 3.4 set values differently in the CPU 
cores, because
when rebooting the same Xen version two or three times again, it's away. 
It will come back
with either Xen version when you switch version. At least it feels that 

>> If I get on your nerves with my time keeping issues
>No, it is good to raise awareness of these issues until they
>are all fixed.  ESPECIALLY if you see time problems in xen-unstable,
>it would be good to get them fixed before 3.4 is final.

Unfortunately, I broke my unstable. Also, it's a semi-productive family 
server, so slots to
Test are a bit rare. I try my best to set it up again and do more 

I have this Time went backwards issues from the beginning. Now I tried 
to set HPET to 32bit,
although I don't know whether a) BIOS is read to use 32bit instead of 
64bit, or b) this makes
any difference, or c) HEPT and TSC have something in common when it 
comes to TSC drifts related
to power management.

I also wondered, whether I should try booting with notsc, but it's a 
dual core and I think then
I need TSC, or don't I?


-----Original Message-----
From: Carsten Schiers [mailto:carsten@xxxxxxxxxx]
Sent: Friday, April 03, 2009 6:52 AM
To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] Huge Time went backwards

Just an observation, to whom it may concern: when booting between 3.3.1 
current xen-3.4-unstable, right after loading powernow-k8, there will be 
one huge
Time went backwards messages (500ms upt to 1,5s), which disappears 
you change Xen version again.

BTW: If I get on your nerves with my time keeping issues, just drop a 
note and 
I keep calm ;-).


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