prev = current;

　　this_CPU = prev->processor;

　　if (in_interrupt())

　　goto scheduling_in_interrupt;

　　release_kernel_lock(prev, this_CPU);

　　/* Do "administrative" work here while we don't hold any locks */

　　if (softirq_active(this_cpu) & softirq_mask(this_CPU))

　　goto handle_softirq;

　　handle_softirq_back:

　　/*

　　* 'sched_data' is protected by the fact that we can run

　　* only one process per CPU.

　　*/

　　sched_data = & aligned_data[this_CPU].schedule_data;

　　spin_lock_irq(&runqueue_lock);

　　/* move an exhausted RR process to be last.. */

　　if (prev->policy == SCHED_RR)

　　goto move_rr_last;

　　move_rr_back:

　　switch (prev->state) {

　　case TASK_INTERRUPTIBLE:

　　if (signal_pending(prev)) {

　　prev->state = TASK_RUNNING;

　　break;

　　}

　　default:

　　#ifdef CONFIG_PREEMPT

　　if (prev->state & TASK_PREEMPTED)

　　break; 如果是内核抢占调度,则保留运行队列

　　#endif

　　del_from_runqueue(prev);

　　#ifdef CONFIG_PREEMPT

　　case TASK_PREEMPTED:

　　#endif

　　case TASK_RUNNING:

　　}

　　prev->need_resched = 0;

　　/*

　　* this is the scheduler proper:

　　*/

　　repeat_schedule:

　　/*

　　* Default process to select..

　　*/

　　next = idle_task(this_CPU);

　　c = -1000;

　　if (task_on_runqueue(prev))

　　goto still_running;

　　still_running_back:

　　list_for_each(tmp, &runqueue_head) {

　　p = list_entry(tmp, struct task_struct, run_list);

　　if (can_schedule(p, this_CPU)) {

　　int weight = goodness(p, this_CPU, prev->active_mm);

　　if (weight > c)