sched: add kernel thread creation and SMP-aware thread scheduling

sched/core.c

@@ -130,6 +130,50 @@ void schedule(enum sched_mode mode)
 	} while (need_resched());
 }
 
+struct runqueue *select_rq_for_thread(struct thread *thr)
+{
+	struct runqueue *best_rq = NULL;
+	unsigned int best_nthreads = 0;
+	unsigned long flags;
+
+	unsigned int nr_cpu = cpu_get_highest_available() + 1;
+	for (unsigned int i = 0; i < nr_cpu; i++) {
+		if (!cpu_is_available(i) || !cpu_is_online(i)) {
+			continue;
+		}
+
+		struct runqueue *rq = cpu_rq(i);
+		if (!rq) {
+			continue;
+		}
+
+		rq_lock(rq, &flags);
+		unsigned int nthreads = rq->rq_nthreads;
+		if (rq->rq_cur && rq->rq_cur != rq->rq_idle) {
+			nthreads++;
+		}
+		rq_unlock(rq, flags);
+
+		if (!best_rq || nthreads < best_nthreads) {
+			best_rq = rq;
+			best_nthreads = nthreads;
+		}
+	}
+
+	return best_rq;
+}
+
+void schedule_thread_on_cpu(struct thread *thr)
+{
+	struct runqueue *rq = select_rq_for_thread(thr);
+	if (rq) {
+		unsigned long flags;
+		rq_lock(rq, &flags);
+		rq_enqueue(rq, thr);
+		rq_unlock(rq, flags);
+	}
+}
+
 void start_charge_period(void)
 {
 	struct thread *self = current_thread();