wake_up_sync的内在运作机制和实现的功能

yc200405

哪位大虾能否给我讲解一下wake_up_sync/wake_up_interruptible_sync的内在运作机制和实现的功能

yidou

void fastcall __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
/**
* __wake_up - sync- wake up threads blocked on a waitqueue.
* @q: the waitqueue
* @mode: which threads
* @nr_exclusive: how many wake-one or wake-many threads to wake up
*
* The sync wakeup differs that the waker knows that it will schedule
* away soon, so while the target thread will be woken up, it will not
* be migrated to another CPU - ie. the two threads are 'synchronized'
* with each other. This can prevent needless bouncing between CPUs.
*
* On UP it can prevent extra preemption.
*/