diff options
| -rw-r--r-- | include/linux/timer.h | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/include/linux/timer.h b/include/linux/timer.h index 7b066fd38248..282e4f2a532a 100644 --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -36,19 +36,30 @@ struct timer_list { #define __TIMER_LOCKDEP_MAP_INITIALIZER(_kn) #endif -/* - * A deferrable timer will work normally when the system is busy, but - * will not cause a CPU to come out of idle just to service it; instead, - * the timer will be serviced when the CPU eventually wakes up with a - * subsequent non-deferrable timer. +/** + * @TIMER_DEFERRABLE: A deferrable timer will work normally when the + * system is busy, but will not cause a CPU to come out of idle just + * to service it; instead, the timer will be serviced when the CPU + * eventually wakes up with a subsequent non-deferrable timer. * - * An irqsafe timer is executed with IRQ disabled and it's safe to wait for - * the completion of the running instance from IRQ handlers, for example, - * by calling del_timer_sync(). + * @TIMER_IRQSAFE: An irqsafe timer is executed with IRQ disabled and + * it's safe to wait for the completion of the running instance from + * IRQ handlers, for example, by calling del_timer_sync(). * * Note: The irq disabled callback execution is a special case for * workqueue locking issues. It's not meant for executing random crap * with interrupts disabled. Abuse is monitored! + * + * @TIMER_PINNED: A pinned timer will not be affected by any timer + * placement heuristics (like, NOHZ) and will always expire on the CPU + * on which the timer was enqueued. + * + * Note: Because enqueuing of timers can migrate the timer from one + * CPU to another, pinned timers are not guaranteed to stay on the + * initialy selected CPU. They move to the CPU on which the enqueue + * function is invoked via mod_timer() or add_timer(). If the timer + * should be placed on a particular CPU, then add_timer_on() has to be + * used. */ #define TIMER_CPUMASK 0x0003FFFF #define TIMER_MIGRATING 0x00040000 |