* See comments there for proper credits.
*/
+#include <linux/sched.h>
#include <linux/clocksource.h>
#include <linux/workqueue.h>
#include <linux/cpufreq.h>
/*
* 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);
{
struct cpufreq_freqs *freq = data;
- if (val != CPUFREQ_RESUMECHANGE && val != CPUFREQ_SUSPENDCHANGE)
- write_seqlock_irq(&xtime_lock);
-
if (!ref_freq) {
if (!freq->old){
ref_freq = freq->new;
- goto end;
+ return 0;
}
ref_freq = freq->old;
loops_per_jiffy_ref = cpu_data[freq->cpu].loops_per_jiffy;
* TSC based sched_clock turns
* to junk w/ cpufreq
*/
- mark_tsc_unstable();
+ mark_tsc_unstable("cpufreq changes");
}
}
}
-end:
- if (val != CPUFREQ_RESUMECHANGE && val != CPUFREQ_SUSPENDCHANGE)
- write_sequnlock_irq(&xtime_lock);
return 0;
}
CLOCK_SOURCE_MUST_VERIFY,
};
-void mark_tsc_unstable(void)
+void mark_tsc_unstable(char *reason)
{
+ sched_clock_unstable_event();
if (!tsc_unstable) {
tsc_unstable = 1;
tsc_enabled = 0;
+ printk("Marking TSC unstable due to: %s.\n", reason);
/* Can be called before registration */
if (clocksource_tsc.mult)
clocksource_change_rating(&clocksource_tsc, 0);