diff options
| -rw-r--r-- | kernel/sched/core.c | 9 | ||||
| -rw-r--r-- | kernel/sched/sched.h | 10 |
2 files changed, 13 insertions, 6 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 13f5857a15ba..7f3063c153d8 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -740,10 +740,11 @@ bool sched_can_stop_tick(void) rq = this_rq(); - /* Make sure rq->nr_running update is visible after the IPI */ - smp_rmb(); - - /* More than one running task need preemption */ + /* + * More than one running task need preemption. + * nr_running update is assumed to be visible + * after IPI is sent from wakers. + */ if (rq->nr_running > 1) return false; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 599a72aff5ea..eb8567610295 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1221,8 +1221,14 @@ static inline void add_nr_running(struct rq *rq, unsigned count) #ifdef CONFIG_NO_HZ_FULL if (prev_nr < 2 && rq->nr_running >= 2) { if (tick_nohz_full_cpu(rq->cpu)) { - /* Order rq->nr_running write against the IPI */ - smp_wmb(); + /* + * Tick is needed if more than one task runs on a CPU. + * Send the target an IPI to kick it out of nohz mode. + * + * We assume that IPI implies full memory barrier and the + * new value of rq->nr_running is visible on reception + * from the target. + */ tick_nohz_full_kick_cpu(rq->cpu); } } |