From: Ingo Molnar this patch is to turn off the TSC-based scheduler clock on NUMA platforms. (ie. platforms that have unsynched TSC for sure.) Those platforms should provide the proper code to rely on the TSC in a global way. (no such infrastructure exists at the moment - the monotonic TSC-based clock doesnt deal with TSC offsets either, as far as i can tell.) arch/i386/kernel/timers/timer_tsc.c | 6 ++++++ 1 files changed, 6 insertions(+) diff -puN arch/i386/kernel/timers/timer_tsc.c~sched-no-tsc-on-numa arch/i386/kernel/timers/timer_tsc.c --- 25/arch/i386/kernel/timers/timer_tsc.c~sched-no-tsc-on-numa 2003-08-03 12:18:51.000000000 -0700 +++ 25-akpm/arch/i386/kernel/timers/timer_tsc.c 2003-08-03 12:18:51.000000000 -0700 @@ -123,7 +123,13 @@ 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 (unlikely(!cpu_has_tsc)) +#endif return (unsigned long long)jiffies * (1000000000 / HZ); /* Read the Time Stamp Counter */ _