Re: [PATCH] x86-64: Fix bad assumption that dualcore cpus havesynced TSCs
From: john stultz
Date: Mon Oct 10 2005 - 13:04:16 EST
On Sat, 2005-10-08 at 14:11 +0400, Vladimir B. Savkin wrote:
> On Fri, Oct 07, 2005 at 02:31:46PM +0200, Andi Kleen wrote:
> > On Friday 07 October 2005 14:26, Vladimir B. Savkin wrote:
> > > On Mon, Sep 19, 2005 at 12:16:43PM -0700, john stultz wrote:
> > > > Andrew,
> > > > This patch should resolve the issue seen in bugme bug #5105, where it
> > > > is assumed that dualcore x86_64 systems have synced TSCs. This is not
> > > > the case, and alternate timesources should be used instead.
> > > >
> > > > For more details, see:
> > > > http://bugzilla.kernel.org/show_bug.cgi?id=5105
> > >
> > > I too have a box that shows the symptoms from bugzilla entry above.
> > > The system is Asus A8V Deluxe MB with
> > > "AMD Athlon(tm) 64 X2 Dual Core Processor 3800+".
> > >
> > > The patch below did not fix the problem, while "idle=poll" did.
> > > Hope this helps, dmesg attached.
> > Are you running the latest BIOS?
> Just upgraded to the lastest BIOS (revision 1014), nothing changed.
> Only with "idle=poll" timers run normally.
>From your dmesg, it appears that there are no other timesources other
then the TSC available on your hardware. So I'm guessing idle=poll is
keeping the CPUs from halting the TSC and keeping them synched.
I would think that the ACPI PM timer would be supported, but I don't see
anything about it in your dmesg. Could you make sure it is properly
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