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Diffstat (limited to 'arch/x86/kernel/tsc.c')
-rw-r--r--arch/x86/kernel/tsc.c38
1 files changed, 19 insertions, 19 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 0e8151b4b..f86453801 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -40,7 +40,7 @@ static int __read_mostly tsc_unstable;
erroneous rdtsc usage on !cpu_has_tsc processors */
static int __read_mostly tsc_disabled = -1;
-static struct static_key __use_tsc = STATIC_KEY_INIT;
+static DEFINE_STATIC_KEY_FALSE(__use_tsc);
int tsc_clocksource_reliable;
@@ -254,7 +254,7 @@ static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
data = cyc2ns_write_begin(cpu);
- rdtscll(tsc_now);
+ tsc_now = rdtsc();
ns_now = cycles_2_ns(tsc_now);
/*
@@ -280,7 +280,12 @@ done:
*/
u64 native_sched_clock(void)
{
- u64 tsc_now;
+ if (static_branch_likely(&__use_tsc)) {
+ u64 tsc_now = rdtsc();
+
+ /* return the value in ns */
+ return cycles_2_ns(tsc_now);
+ }
/*
* Fall back to jiffies if there's no TSC available:
@@ -290,16 +295,17 @@ u64 native_sched_clock(void)
* very important for it to be as fast as the platform
* can achieve it. )
*/
- if (!static_key_false(&__use_tsc)) {
- /* No locking but a rare wrong value is not a big deal: */
- return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
- }
- /* read the Time Stamp Counter: */
- rdtscll(tsc_now);
+ /* No locking but a rare wrong value is not a big deal: */
+ return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
+}
- /* return the value in ns */
- return cycles_2_ns(tsc_now);
+/*
+ * Generate a sched_clock if you already have a TSC value.
+ */
+u64 native_sched_clock_from_tsc(u64 tsc)
+{
+ return cycles_2_ns(tsc);
}
/* We need to define a real function for sched_clock, to override the
@@ -314,12 +320,6 @@ unsigned long long
sched_clock(void) __attribute__((alias("native_sched_clock")));
#endif
-unsigned long long native_read_tsc(void)
-{
- return __native_read_tsc();
-}
-EXPORT_SYMBOL(native_read_tsc);
-
int check_tsc_unstable(void)
{
return tsc_unstable;
@@ -982,7 +982,7 @@ static struct clocksource clocksource_tsc;
*/
static cycle_t read_tsc(struct clocksource *cs)
{
- return (cycle_t)get_cycles();
+ return (cycle_t)rdtsc_ordered();
}
/*
@@ -1218,7 +1218,7 @@ void __init tsc_init(void)
/* now allow native_sched_clock() to use rdtsc */
tsc_disabled = 0;
- static_key_slow_inc(&__use_tsc);
+ static_branch_enable(&__use_tsc);
if (!no_sched_irq_time)
enable_sched_clock_irqtime();