Re: 2.6.12-mm1 boot failure on NUMA box.

Ingo Molnar
2005-06-24T19:54:29Z

* Martin J. Bligh <mbligh@mbligh.org> wrote:

> > - /*
> > - * In the NUMA case we dont use the TSC as they are not
> > - * synchronized across all CPUs.
> > - */
> > -#ifndef CONFIG_NUMA
> > - if (!use_tsc)
> > -#endif
> > + if (!cpu_has_tsc)
> > /* no locking but a rare wrong value is not a big deal */
> > return jiffies_64 * (1000000000 / HZ);
>
> Humpf. That does look dangerous on a NUMA-Q. The TSCs aren't synced,
> and we can't use them .... have to use PIT, whether the CPUs have TSC
> or not.

is the only problem the unsyncedness? That should be fine as far as the
scheduler is concerned. (we compensate for per-CPU drifts)

Ingo