diff options
Diffstat (limited to 'include/linux/interrupt.h')
| -rw-r--r-- | include/linux/interrupt.h | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 457151f9f263..8cd9327e4e78 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -616,6 +616,53 @@ extern void __raise_softirq_irqoff(unsigned int nr); extern void raise_softirq_irqoff(unsigned int nr); extern void raise_softirq(unsigned int nr); +/* + * With forced-threaded interrupts enabled a raised softirq is deferred to + * ksoftirqd unless it can be handled within the threaded interrupt. This + * affects timer_list timers and hrtimers which are explicitly marked with + * HRTIMER_MODE_SOFT. + * With PREEMPT_RT enabled more hrtimers are moved to softirq for processing + * which includes all timers which are not explicitly marked HRTIMER_MODE_HARD. + * Userspace controlled timers (like the clock_nanosleep() interface) is divided + * into two categories: Tasks with elevated scheduling policy including + * SCHED_{FIFO|RR|DL} and the remaining scheduling policy. The tasks with the + * elevated scheduling policy are woken up directly from the HARDIRQ while all + * other wake ups are delayed to softirq and so to ksoftirqd. + * + * The ksoftirqd runs at SCHED_OTHER policy at which it should remain since it + * handles the softirq in an overloaded situation (not handled everything + * within its last run). + * If the timers are handled at SCHED_OTHER priority then they competes with all + * other SCHED_OTHER tasks for CPU resources are possibly delayed. + * Moving timers softirqs to a low priority SCHED_FIFO thread instead ensures + * that timer are performed before scheduling any SCHED_OTHER thread. + */ +DECLARE_PER_CPU(struct task_struct *, ktimerd); +DECLARE_PER_CPU(unsigned long, pending_timer_softirq); +void raise_ktimers_thread(unsigned int nr); + +static inline unsigned int local_timers_pending_force_th(void) +{ + return __this_cpu_read(pending_timer_softirq); +} + +static inline void raise_timer_softirq(unsigned int nr) +{ + lockdep_assert_in_irq(); + if (force_irqthreads()) + raise_ktimers_thread(nr); + else + __raise_softirq_irqoff(nr); +} + +static inline unsigned int local_timers_pending(void) +{ + if (force_irqthreads()) + return local_timers_pending_force_th(); + else + return local_softirq_pending(); +} + DECLARE_PER_CPU(struct task_struct *, ksoftirqd); static inline struct task_struct *this_cpu_ksoftirqd(void) |