Re: 2.6.12-mm1 boot failure on NUMA box.

[Ingo Molnar <mingo@elte.hu>]

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

> 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);