extern uthread_struct_t *sched_find_best_uthread(kthread_runqueue_t *kthread_runq)
{
/* [1] Tries to find the highest priority RUNNABLE uthread in active-runq.
* [2] Found - Jump to [FOUND]
* [3] Switches runqueues (active/expires)
* [4] Repeat [1] through [2]
* [NOT FOUND] Return NULL(no more jobs)
* [FOUND] Remove uthread from pq and return it. */
rbtree rbrunq = kthread_runq->cfs_rq;
rbtree_node node = find_leftmost(rbrunq);
uthread_struct_t *u_obj;
gt_spin_lock(&(kthread_runq->kthread_runqlock));
kthread_runq->kthread_runqlock.holder = 0x04;
if(rbrunq->nr_running == 0 || !node){ //If there are no more nodes to schedule, return NULL.
gt_spin_unlock(&(kthread_runq->kthread_runqlock));
return NULL;
}
u_obj = (uthread_struct_t *) node->value; //Else get the uthread in the leftmost node.
update_min_vruntime(kthread_runq, u_obj->vruntime); //Set the min_vruntime of the runqueue to this uthread's vruntime.
__rem_from_cfs_runqueue(rbrunq,u_obj); //Remove the object from the CFS tree.
gt_spin_unlock(&(kthread_runq->kthread_runqlock));
return u_obj; //Return the leftmost node.
#if 0
printf("cpu(%d) : sched best uthread(id:%d, group:%d)\n", u_obj->cpu_id, u_obj->uthread_tid, u_obj->uthread_gid);
#endif
}
//Find leftmost node
node* find_leftmost (node *curNode, node *prevNode) {
if (curNode->left == NULL) {
return curNode;
} else {
prevNode = curNode;
return find_leftmost (curNode->left, prevNode);
}
}
//Recursively write the tree in ascending order
int write_ascending (node* curNode, node* rootNode, node* prevNode, FILE *outFile) {
return deleteNode (write (find_leftmost (curNode, prevNode), outFile), rootNode, prevNode);
}