diff options
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/clock.c | 57 | ||||
| -rw-r--r-- | kernel/sched/core.c | 1 | ||||
| -rw-r--r-- | kernel/sched/debug.c | 2 |
3 files changed, 40 insertions, 20 deletions
diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index 10c83e73837a..e3e3b979f9bd 100644 --- a/kernel/sched/clock.c +++ b/kernel/sched/clock.c @@ -53,6 +53,7 @@ * */ #include "sched.h" +#include <linux/sched_clock.h> /* * Scheduler clock - returns current time in nanosec units. @@ -66,12 +67,7 @@ unsigned long long __weak sched_clock(void) } EXPORT_SYMBOL_GPL(sched_clock); -__read_mostly int sched_clock_running; - -void sched_clock_init(void) -{ - sched_clock_running = 1; -} +static DEFINE_STATIC_KEY_FALSE(sched_clock_running); #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK /* @@ -195,17 +191,40 @@ void clear_sched_clock_stable(void) smp_mb(); /* matches sched_clock_init_late() */ - if (sched_clock_running == 2) + if (static_key_count(&sched_clock_running.key) == 2) __clear_sched_clock_stable(); } +static void __sched_clock_gtod_offset(void) +{ + struct sched_clock_data *scd = this_scd(); + + __scd_stamp(scd); + __gtod_offset = (scd->tick_raw + __sched_clock_offset) - scd->tick_gtod; +} + +void __init sched_clock_init(void) +{ + /* + * Set __gtod_offset such that once we mark sched_clock_running, + * sched_clock_tick() continues where sched_clock() left off. + * + * Even if TSC is buggered, we're still UP at this point so it + * can't really be out of sync. + */ + local_irq_disable(); + __sched_clock_gtod_offset(); + local_irq_enable(); + + static_branch_inc(&sched_clock_running); +} /* * We run this as late_initcall() such that it runs after all built-in drivers, * notably: acpi_processor and intel_idle, which can mark the TSC as unstable. */ static int __init sched_clock_init_late(void) { - sched_clock_running = 2; + static_branch_inc(&sched_clock_running); /* * Ensure that it is impossible to not do a static_key update. * @@ -350,8 +369,8 @@ u64 sched_clock_cpu(int cpu) if (sched_clock_stable()) return sched_clock() + __sched_clock_offset; - if (unlikely(!sched_clock_running)) - return 0ull; + if (!static_branch_unlikely(&sched_clock_running)) + return sched_clock(); preempt_disable_notrace(); scd = cpu_sdc(cpu); @@ -373,7 +392,7 @@ void sched_clock_tick(void) if (sched_clock_stable()) return; - if (unlikely(!sched_clock_running)) + if (!static_branch_unlikely(&sched_clock_running)) return; lockdep_assert_irqs_disabled(); @@ -385,8 +404,6 @@ void sched_clock_tick(void) void sched_clock_tick_stable(void) { - u64 gtod, clock; - if (!sched_clock_stable()) return; @@ -398,9 +415,7 @@ void sched_clock_tick_stable(void) * TSC to be unstable, any computation will be computing crap. */ local_irq_disable(); - gtod = ktime_get_ns(); - clock = sched_clock(); - __gtod_offset = (clock + __sched_clock_offset) - gtod; + __sched_clock_gtod_offset(); local_irq_enable(); } @@ -434,9 +449,17 @@ EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event); #else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */ +void __init sched_clock_init(void) +{ + static_branch_inc(&sched_clock_running); + local_irq_disable(); + generic_sched_clock_init(); + local_irq_enable(); +} + u64 sched_clock_cpu(int cpu) { - if (unlikely(!sched_clock_running)) + if (!static_branch_unlikely(&sched_clock_running)) return 0; return sched_clock(); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index d17d99778356..c45de46fdf10 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5916,7 +5916,6 @@ void __init sched_init(void) int i, j; unsigned long alloc_size = 0, ptr; - sched_clock_init(); wait_bit_init(); #ifdef CONFIG_FAIR_GROUP_SCHED diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 870d4f3da285..60caf1fb94e0 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -622,8 +622,6 @@ void print_dl_rq(struct seq_file *m, int cpu, struct dl_rq *dl_rq) #undef PU } -extern __read_mostly int sched_clock_running; - static void print_cpu(struct seq_file *m, int cpu) { struct rq *rq = cpu_rq(cpu); |