Commit bb29ab26 authored by Ingo Molnar's avatar Ingo Molnar

sched: x86, track TSC-unstable events

track TSC-unstable events and propagate it to the scheduler code.
Also allow sched_clock() to be used when the TSC is unstable,
the rq_clock() wrapper creates a reliable clock out of it.
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent dd41f596
......@@ -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;
......
......@@ -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
......
......@@ -67,6 +67,13 @@ unsigned long long __attribute__((weak)) sched_clock(void)
return (unsigned long long)jiffies * (1000000000 / HZ);
}
/*
* 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 ],
......
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