diff options
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/tick-sched.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index acbe6722cf75..197a3bd882ad 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -324,14 +324,28 @@ void tick_nohz_full_kick_cpu(int cpu) static void tick_nohz_kick_task(struct task_struct *tsk) { - int cpu = task_cpu(tsk); + int cpu; + + /* + * If the task is not running, run_posix_cpu_timers() + * has nothing to elapse, IPI can then be spared. + * + * activate_task() STORE p->tick_dep_mask + * STORE p->on_rq + * __schedule() (switch to task 'p') smp_mb() (atomic_fetch_or()) + * LOCK rq->lock LOAD p->on_rq + * smp_mb__after_spin_lock() + * tick_nohz_task_switch() + * LOAD p->tick_dep_mask + */ + if (!sched_task_on_rq(tsk)) + return; /* * If the task concurrently migrates to another CPU, * we guarantee it sees the new tick dependency upon * schedule. * - * * set_task_cpu(p, cpu); * STORE p->cpu = @cpu * __schedule() (switch to task 'p') @@ -340,6 +354,7 @@ static void tick_nohz_kick_task(struct task_struct *tsk) * tick_nohz_task_switch() smp_mb() (atomic_fetch_or()) * LOAD p->tick_dep_mask LOAD p->cpu */ + cpu = task_cpu(tsk); preempt_disable(); if (cpu_online(cpu)) |