Re: AMD X2 unsynced TSC fix?

Sergio Monteiro Basto
2006-10-28T03:58:31Z

On Fri, 2006-10-27 at 18:08 -0400, Lee Revell wrote:
> On Fri, 2006-10-27 at 15:48 -0600, Chris Friesen wrote:
> > Lee Revell wrote:
> >
> > > What exactly does that AMD patch do?
> >
> > "...by periodically adjusting the core time-stamp-counters, so that they
> > are synchronized."
> >
> > It sounds like they just periodically write a new value to the TSC.
> > Presumably they set the "slower" one equal to the "faster" one.
> >
> > You'd likely still have windows where time might run backwards, but it
> > would be better than nothing.
>
> The patch also apparently changes boot params to make the OS use the
> ACPI PM timer, so it must not be a complete solution.

Hi,
So far, has I can understand. Seems to me that my computer which have a
Pentium D (Dual Core) on VIA chipset, also have unsynchronized TSC and
with the patch of hrtimers on
( http://www.tglx.de/projects/hrtimers/2.6.18/ )
Kernel found and use a new clocksource, the acpi_pm. And works stable
but I don't deny that could be a little slower.

Just to point out. This could be more a problem of chipsets than CPUs
(AMD or Intel). AMD just begin first using x86_64 archs :)

Last Note:
I still have other minor problem, seems (to me) related with SATA
drives. Kernel 2.4.19-rc3 have big changes on SATA and I like to test it
but can't apply hrtimers patch (I don't understand half seems in kernel
other half not).
In rc3 with jiffies clocksource even with boot parameter "notsc" I have
unsynchronized issues and many "Lost timer tickets", but I can say that
is a regression because computer never work well.

Thanks,
--
Sérgio M. B.