__wake_up_sync — wake up threads blocked on a waitqueue.
void __wake_up_sync ( | wait_queue_head_t * | q, |
| unsigned int | mode, | |
| int | nr_exclusive); |
qthe waitqueue
modewhich threads
nr_exclusivehow 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.