diff options
| -rw-r--r-- | arch/i386/kernel/tsc.c | 9 | ||||
| -rw-r--r-- | include/linux/sched.h | 2 | ||||
| -rw-r--r-- | kernel/sched.c | 7 |
3 files changed, 17 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; diff --git a/include/linux/sched.h b/include/linux/sched.h index be2460e6f55..fa895b309da 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1321,6 +1321,8 @@ extern void sched_exec(void); #define sched_exec() {} #endif +extern void sched_clock_unstable_event(void); + #ifdef CONFIG_HOTPLUG_CPU extern void idle_task_exit(void); #else diff --git a/kernel/sched.c b/kernel/sched.c index 01ba4b1848a..6150cd70f44 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -68,6 +68,13 @@ unsigned long long __attribute__((weak)) sched_clock(void) } /* + * CPU frequency is/was unstable - start new by setting prev_clock_raw: + */ +void sched_clock_unstable_event(void) +{ +} + +/* * Convert user-nice values [ -20 ... 0 ... 19 ] * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ], * and back. |