diff options
| -rw-r--r-- | include/linux/sched.h | 5 | ||||
| -rw-r--r-- | init/main.c | 1 | ||||
| -rw-r--r-- | kernel/sched/clock.c | 50 | ||||
| -rw-r--r-- | kernel/sched/core.c | 4 |
4 files changed, 31 insertions, 29 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index ad3ec9ec61f7..94a48bb58297 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2515,6 +2515,10 @@ extern u64 sched_clock_cpu(int cpu); extern void sched_clock_init(void); #ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK +static inline void sched_clock_init_late(void) +{ +} + static inline void sched_clock_tick(void) { } @@ -2537,6 +2541,7 @@ static inline u64 local_clock(void) return sched_clock(); } #else +extern void sched_clock_init_late(void); /* * Architectures can set this to 1 if they have specified * CONFIG_HAVE_UNSTABLE_SCHED_CLOCK in their arch Kconfig, diff --git a/init/main.c b/init/main.c index b0c9d6facef9..19228149386c 100644 --- a/init/main.c +++ b/init/main.c @@ -625,7 +625,6 @@ asmlinkage __visible void __init start_kernel(void) numa_policy_init(); if (late_time_init) late_time_init(); - sched_clock_init(); calibrate_delay(); pidmap_init(); anon_vma_init(); diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index 5d6dd38b449c..b3466d4e0cc2 100644 --- a/kernel/sched/clock.c +++ b/kernel/sched/clock.c @@ -77,6 +77,11 @@ EXPORT_SYMBOL_GPL(sched_clock); __read_mostly int sched_clock_running; +void sched_clock_init(void) +{ + sched_clock_running = 1; +} + #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK static DEFINE_STATIC_KEY_FALSE(__sched_clock_stable); static int __sched_clock_stable_early; @@ -96,12 +101,18 @@ void set_sched_clock_stable(void) { __sched_clock_stable_early = 1; - smp_mb(); /* matches sched_clock_init() */ - - if (!sched_clock_running) - return; + smp_mb(); /* matches sched_clock_init_late() */ - __set_sched_clock_stable(); + /* + * This really should only be called early (before + * sched_clock_init_late()) when guestimating our sched_clock() is + * solid. + * + * After that we test stability and we can negate our guess using + * clear_sched_clock_stable, possibly from a watchdog. + */ + if (WARN_ON_ONCE(sched_clock_running == 2)) + __set_sched_clock_stable(); } static void __clear_sched_clock_stable(struct work_struct *work) @@ -117,12 +128,10 @@ void clear_sched_clock_stable(void) { __sched_clock_stable_early = 0; - smp_mb(); /* matches sched_clock_init() */ - - if (!sched_clock_running) - return; + smp_mb(); /* matches sched_clock_init_late() */ - schedule_work(&sched_clock_work); + if (sched_clock_running == 2) + schedule_work(&sched_clock_work); } struct sched_clock_data { @@ -143,20 +152,9 @@ static inline struct sched_clock_data *cpu_sdc(int cpu) return &per_cpu(sched_clock_data, cpu); } -void sched_clock_init(void) +void sched_clock_init_late(void) { - u64 ktime_now = ktime_to_ns(ktime_get()); - int cpu; - - for_each_possible_cpu(cpu) { - struct sched_clock_data *scd = cpu_sdc(cpu); - - scd->tick_raw = 0; - scd->tick_gtod = ktime_now; - scd->clock = ktime_now; - } - - sched_clock_running = 1; + sched_clock_running = 2; /* * Ensure that it is impossible to not do a static_key update. @@ -362,11 +360,6 @@ EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event); #else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */ -void sched_clock_init(void) -{ - sched_clock_running = 1; -} - u64 sched_clock_cpu(int cpu) { if (unlikely(!sched_clock_running)) @@ -374,6 +367,7 @@ u64 sched_clock_cpu(int cpu) return sched_clock(); } + #endif /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */ /* diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a129b34b8206..96a4267e6020 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7498,6 +7498,7 @@ void __init sched_init_smp(void) init_sched_dl_class(); sched_init_smt(); + sched_clock_init_late(); sched_smp_initialized = true; } @@ -7513,6 +7514,7 @@ early_initcall(migration_init); void __init sched_init_smp(void) { sched_init_granularity(); + sched_clock_init_late(); } #endif /* CONFIG_SMP */ @@ -7556,6 +7558,8 @@ void __init sched_init(void) int i, j; unsigned long alloc_size = 0, ptr; + sched_clock_init(); + for (i = 0; i < WAIT_TABLE_SIZE; i++) init_waitqueue_head(bit_wait_table + i); |