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    SubjectRe: 2.6.12-mm1 boot failure on NUMA box.
    >> OK, still broken with the last 3 backed out, but works with the last 4 
    >> backed out. So I guess it's scheduler-cache-hot-autodetect.patch that
    >> breaks it. Con just sent me something else to try to fix it in order
    >> to run next ... will do that.
    >
    > hm. Does it work if you disable migration-autodetect via passing in e.g.
    > migration_cost=1000,2000,3000 on the boot line? Is it perhaps the
    > excessive debugging that hurts.
    >
    > or does it work if you undo the chunk below? Seemed harmless, but has
    > CONFIG_NUMA relevance.
    >
    > Ingo
    >
    > --- linux/arch/i386/kernel/timers/timer_tsc.c.orig
    > +++ linux/arch/i386/kernel/timers/timer_tsc.c
    > @@ -133,18 +133,15 @@ static unsigned long long monotonic_cloc
    >
    > /*
    > * Scheduler clock - returns current time in nanosec units.
    > + *
    > + * it's not a problem if the TSC is unsynchronized,
    > + * as the scheduler will carefully compensate for it.
    > */
    > unsigned long long sched_clock(void)
    > {
    > unsigned long long this_offset;
    >
    > - /*
    > - * 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.

    M.
    -
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