[Xen-devel] RE: [PATCH] clocksource=tsc

["Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>]

Nope, its not ntpd.  Everything seemed fine for at
least 15-20 minutes, then I went away for awhile
and when I checked back an hour later, same weird
symptoms as before.

I also tried running with nosmp on the xen boot line
(and confirmed that only one processor was started).
Same results... after about an hour.  So it doesn't
appear to be a result of cross-CPU time issues.

> From: Dan Magenheimer [mailto:dan.magenheimer@xxxxxxxxxx]
> 
> I'm thinking the problem may only occur when dom0 is
> running ntpd.  Maybe "setting" the platform time only
> changes one CPU, or sets the platform time differently
> than system time?
> 
> > -----Original Message-----
> > From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx]
> > Sent: Wednesday, July 16, 2008 6:50 AM
> > To: dan.magenheimer@xxxxxxxxxx; Xen-Devel (E-mail)
> > Cc: Dave Winchell
> > Subject: Re: [PATCH] clocksource=tsc
> > 
> > 
> > That's a weird set of symptoms. Perhaps dom0's sense of 
> system time is
> > diverging from Xen's? I don't see that CPUs can diverge, if 
> > their TSCs are
> > in sync, since we shouldn't be dynamically modifying the 
> > per-CPU timestamps
> > or scale factors.
> > 
> >  -- Keir
> > 
> > On 16/7/08 13:43, "Dan Magenheimer" 
> > <dan.magenheimer@xxxxxxxxxx> wrote:
> > 
> > > Well now I have to take that back.  It DOESN'T work yet.
> > > I think I am experiencing "Weirdness can happen..."
> > > when booting with clocksource=tsc... I was away from
> > > the machine overnight but the symptoms I've seen before
> > > are that the system becomes less snappy and eventually
> > > grinds to a near-halt.
> > >
> > > Oddly, I can login most of the way on the console
> > > and launch new xterm's in my VNC display, but I never
> > > get a prompt, and I can't interrupt a process I left
> > > running overnight in another xterm.  The time display
> > > in gnome seems to have frozen about an hour after
> > > I booted.  Pinging the machine works but ssh'ing to
> > > it doesn't ("Connection closed")



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