sched: track CPU clock cycles used by threads

sched/core.c

@@ -7,6 +7,8 @@ extern kern_status_t setup_kernel_task(void);
 extern kern_status_t task_object_type_init(void);
 extern kern_status_t thread_object_type_init(void);
 
+static cycles_t __default_quantum = 0;
+
 kern_status_t sched_init(void)
 {
 	kern_status_t status = KERN_OK;
@@ -33,5 +35,47 @@ kern_status_t sched_init(void)
 	this_cpu->c_current_thread = this_thread;
 	put_cpu(this_cpu);
 
+	start_charge_period();
+
 	return status;
 }
+
+void start_charge_period(void)
+{
+	struct thread *self = current_thread();
+	if (!self) {
+		return;
+	}
+
+	self->tr_charge_period_start = get_cycles();
+}
+
+void end_charge_period(void)
+{
+	preempt_disable();
+	struct thread *self = current_thread();
+	if (!self) {
+		return;
+	}
+
+	cycles_t end = get_cycles();
+	preempt_enable();
+
+	cycles_t charge = cycles_diff(self->tr_charge_period_start, end);
+
+	self->tr_quantum_cycles += charge;
+	self->tr_total_cycles += charge;
+
+	if (self->tr_quantum_cycles >= self->tr_quantum_target) {
+		self->tr_flags |= THREAD_F_NEED_RESCHED;
+	}
+
+	self->tr_charge_period_start = 0;
+
+	//printk("%llu cycles charged to %s/%u", charge, self->tr_parent->t_name, self->tr_parent->t_id);
+}
+
+cycles_t default_quantum(void)
+{
+	return __default_quantum;
+}

sched/task.c

@@ -40,6 +40,7 @@ kern_status_t setup_kernel_task(void)
 	kernel_thread->tr_prio = PRIO_NORMAL;
 	kernel_thread->tr_state = THREAD_READY;
 	kernel_thread->tr_parent = __kernel_task;
+	kernel_thread->tr_quantum_target = default_quantum();
 
 	unsigned long flags;
 	task_lock_irqsave(__kernel_task, &flags);