diff options
Diffstat (limited to 'arch/i386/kernel/tsc.c')
| -rw-r--r-- | arch/i386/kernel/tsc.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c index f64b81f3033..ea63a30ca3e 100644 --- a/arch/i386/kernel/tsc.c +++ b/arch/i386/kernel/tsc.c @@ -4,6 +4,7 @@ * See comments there for proper credits. */ +#include <linux/sched.h> #include <linux/clocksource.h> #include <linux/workqueue.h> #include <linux/cpufreq.h> @@ -106,8 +107,13 @@ unsigned long long sched_clock(void) /* * Fall back to jiffies if there's no TSC available: + * ( But note that we still use it if the TSC is marked + * unstable. We do this because unlike Time Of Day, + * the scheduler clock tolerates small errors and it's + * very important for it to be as fast as the platform + * can achive it. ) */ - if (unlikely(!tsc_enabled)) + if (unlikely(!tsc_enabled && !tsc_unstable)) /* No locking but a rare wrong value is not a big deal: */ return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ); @@ -277,6 +283,7 @@ static struct clocksource clocksource_tsc = { void mark_tsc_unstable(char *reason) { + sched_clock_unstable_event(); if (!tsc_unstable) { tsc_unstable = 1; tsc_enabled = 0; |