diff options
| -rw-r--r-- | arch/x86/kernel/tsc.c | 2 | ||||
| -rw-r--r-- | include/linux/preempt.h | 5 | ||||
| -rw-r--r-- | kernel/sched/clock.c | 53 | ||||
| -rw-r--r-- | kernel/sched/fair.c | 8 |
4 files changed, 43 insertions, 25 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index a3acbac2ee72..19e5adb49a27 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -180,7 +180,7 @@ static void cyc2ns_write_end(int cpu, struct cyc2ns_data *data) static void cyc2ns_data_init(struct cyc2ns_data *data) { - data->cyc2ns_mul = 1U << CYC2NS_SCALE_FACTOR; + data->cyc2ns_mul = 0; data->cyc2ns_shift = CYC2NS_SCALE_FACTOR; data->cyc2ns_offset = 0; data->__count = 0; diff --git a/include/linux/preempt.h b/include/linux/preempt.h index 59749fc48328..de83b4eb1642 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -134,7 +134,6 @@ do { \ #undef preempt_check_resched #endif -#ifdef CONFIG_PREEMPT #define preempt_set_need_resched() \ do { \ set_preempt_need_resched(); \ @@ -144,10 +143,6 @@ do { \ if (tif_need_resched()) \ set_preempt_need_resched(); \ } while (0) -#else -#define preempt_set_need_resched() do { } while (0) -#define preempt_fold_need_resched() do { } while (0) -#endif #ifdef CONFIG_PREEMPT_NOTIFIERS diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index 6bd6a6731b21..43c2bcc35761 100644 --- a/kernel/sched/clock.c +++ b/kernel/sched/clock.c @@ -77,35 +77,50 @@ __read_mostly int sched_clock_running; #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK static struct static_key __sched_clock_stable = STATIC_KEY_INIT; +static int __sched_clock_stable_early; int sched_clock_stable(void) { - if (static_key_false(&__sched_clock_stable)) - return false; - return true; + return static_key_false(&__sched_clock_stable); } -void set_sched_clock_stable(void) +static void __set_sched_clock_stable(void) { if (!sched_clock_stable()) - static_key_slow_dec(&__sched_clock_stable); + static_key_slow_inc(&__sched_clock_stable); +} + +void set_sched_clock_stable(void) +{ + __sched_clock_stable_early = 1; + + smp_mb(); /* matches sched_clock_init() */ + + if (!sched_clock_running) + return; + + __set_sched_clock_stable(); } static void __clear_sched_clock_stable(struct work_struct *work) { /* XXX worry about clock continuity */ if (sched_clock_stable()) - static_key_slow_inc(&__sched_clock_stable); + static_key_slow_dec(&__sched_clock_stable); } static DECLARE_WORK(sched_clock_work, __clear_sched_clock_stable); void clear_sched_clock_stable(void) { - if (keventd_up()) - schedule_work(&sched_clock_work); - else - __clear_sched_clock_stable(&sched_clock_work); + __sched_clock_stable_early = 0; + + smp_mb(); /* matches sched_clock_init() */ + + if (!sched_clock_running) + return; + + schedule_work(&sched_clock_work); } struct sched_clock_data { @@ -140,6 +155,20 @@ void sched_clock_init(void) } sched_clock_running = 1; + + /* + * Ensure that it is impossible to not do a static_key update. + * + * Either {set,clear}_sched_clock_stable() must see sched_clock_running + * and do the update, or we must see their __sched_clock_stable_early + * and do the update, or both. + */ + smp_mb(); /* matches {set,clear}_sched_clock_stable() */ + + if (__sched_clock_stable_early) + __set_sched_clock_stable(); + else + __clear_sched_clock_stable(NULL); } /* @@ -340,7 +369,7 @@ EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event); */ u64 cpu_clock(int cpu) { - if (static_key_false(&__sched_clock_stable)) + if (!sched_clock_stable()) return sched_clock_cpu(cpu); return sched_clock(); @@ -355,7 +384,7 @@ u64 cpu_clock(int cpu) */ u64 local_clock(void) { - if (static_key_false(&__sched_clock_stable)) + if (!sched_clock_stable()) return sched_clock_cpu(raw_smp_processor_id()); return sched_clock(); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 867b0a4b0893..966cc2bfcb77 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2360,13 +2360,7 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, } wakeup = 0; } else { - /* - * Task re-woke on same cpu (or else migrate_task_rq_fair() - * would have made count negative); we must be careful to avoid - * double-accounting blocked time after synchronizing decays. - */ - se->avg.last_runnable_update += __synchronize_entity_decay(se) - << 20; + __synchronize_entity_decay(se); } /* migrated tasks did not contribute to our blocked load */ |