void check_scheduling(void)
{
uint32_t prio = get_highest_priority();
task_t* curr_task = per_core(current_task);
if (prio > curr_task->prio) {
reschedule();
#ifdef DYNAMIC_TICKS
} else if ((prio > 0) && (prio == curr_task->prio)) {
// if a task is ready, check if the current task runs already one tick (one time slice)
// => reschedule to realize round robin
const uint64_t diff_cycles = get_rdtsc() - curr_task->last_tsc;
const uint64_t cpu_freq_hz = 1000000ULL * (uint64_t) get_cpu_frequency();
if (((diff_cycles * (uint64_t) TIMER_FREQ) / cpu_freq_hz) > 0) {
LOG_DEBUG("Time slice expired for task %d on core %d. New task has priority %u.\n", curr_task->id, CORE_ID, prio);
reschedule();
}
#endif
}
}
/* Up or "V" operation on a semaphore. Increments SEMA's value
and wakes up one thread of those waiting for SEMA, if any.
This function may be called from an interrupt handler. */
void
sema_up (struct semaphore *sema)
{
enum intr_level old_level;
ASSERT (sema != NULL);
old_level = intr_disable ();
if (!list_empty (&sema->waiters))
{
/* Unblocks the thread with the highest priority in the
sema->waiters list. */
struct list_elem *e = get_highest_priority (&sema->waiters);
struct thread *t = list_entry (e, struct thread, elem);
list_remove (e);
thread_unblock (t);
}
sema->value++;
/* A thread is unblocked: checks if the current should yield. */
highest_priority_test ();
intr_set_level (old_level);
}
