Re: AMD X2 unsynced TSC fix?

Andrew Morton
2006-10-28T07:14:09Z

On Fri, 27 Oct 2006 23:49:24 -0700
thockin@hockin.org wrote:

> On Fri, Oct 27, 2006 at 11:46:15PM -0700, Andrew Morton wrote:
> > On Fri, 27 Oct 2006 23:35:24 -0700
> > thockin@hockin.org wrote:
> >
> > > On Fri, Oct 27, 2006 at 09:06:12PM -0700, Andi Kleen wrote:
> > > >
> > > > > 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
> > > >
> > > > Intel systems (except for some large highend systems) have synchronized TSCs.
> > >
> > > Does Intel guarantee that, or is that just what we happen to see, so far.
> >
> > Matthias has a Xeon machine on which the TSCs are unsynced, and which are
> > unsyncable - write_tsc() just doesn't do anything. See thread at
> > http://lkml.org/lkml/2006/7/22/104
>
> Nothing at all, or just the the low few bits are writeable?

We don't know - the tsc sync code doesn't remeasure the errors after "correcting"
them.