diff options
author | Mike Galbraith <umgwanakikbuti@gmail.com> | 2015-04-11 15:15:59 +0200 |
---|---|---|
committer | Anders Roxell <anders.roxell@linaro.org> | 2015-06-01 12:03:40 +0200 |
commit | 51ebaaeec8dbd08a7d6b8758256e9899b497aed3 (patch) | |
tree | a1b429b943639ebb4cb823bc87434adb9743374e | |
parent | 443f4109a72f13afacfb936a3752ac207b64fb29 (diff) |
rt, nohz_full: fix nohz_full for PREEMPT_RT_FULL
A task being ticked and trying to shut the tick down will fail due
to having just awakened ksoftirqd, subtract it from nr_running.
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r-- | kernel/sched/core.c | 29 | ||||
-rw-r--r-- | kernel/time/tick-sched.c | 5 |
2 files changed, 28 insertions, 6 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 883669d3e293..71c0bb1cdeb0 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -696,17 +696,34 @@ static inline bool got_nohz_idle_kick(void) #endif /* CONFIG_NO_HZ_COMMON */ #ifdef CONFIG_NO_HZ_FULL + +static int ksoftirqd_running(void) +{ + struct task_struct *softirqd; + + if (!IS_ENABLED(CONFIG_PREEMPT_RT_FULL)) + return 0; + softirqd = this_cpu_ksoftirqd(); + if (softirqd && softirqd->on_rq) + return 1; + return 0; +} + bool sched_can_stop_tick(void) { - struct rq *rq; + struct rq *rq; - rq = this_rq(); + rq = this_rq(); - /* Make sure rq->nr_running update is visible after the IPI */ - smp_rmb(); + /* Make sure rq->nr_running update is visible after the IPI */ + smp_rmb(); - /* More than one running task need preemption */ - if (rq->nr_running > 1) + /* + * More than one running task need preemption + * + * NOTE, RT: if ksoftirqd is awake, subtract it. + */ + if (rq->nr_running - ksoftirqd_running() > 1) return false; return true; diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 6c97081f67f9..57d5bb1b3919 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -226,7 +226,12 @@ void __tick_nohz_full_check(void) static void nohz_full_kick_work_func(struct irq_work *work) { + unsigned long flags; + + /* ksoftirqd processes sirqs with interrupts enabled */ + local_irq_save(flags); __tick_nohz_full_check(); + local_irq_restore(flags); } static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = { |