BSD bind cpu

主要路径：

sched_bind=>
       ts->ts_cpu = cpu
mi_switch(SW_VOL, NULL)=>主动放弃运行

sched_switch=>

        sched_switch_migrate()
         cpu_switch()


Linux:
    sched_setaffinity=>cpuset_cpus_allowed
                     =>set_cpus_allowed_ptr=>migrate_task
 /*
 * This is how migration works:
 *
 * 1) we queue a struct migration_req structure in the source CPU's
 *    runqueue and wake up that CPU's migration thread.
 * 2) we down() the locked semaphore => thread blocks.
 * 3) migration thread wakes up (implicitly it forces the migrated
 *    thread off the CPU)
 * 4) it gets the migration request and checks whether the migrated
 *    task is still in the wrong runqueue.
 * 5) if it's in the wrong runqueue then the migration thread removes
 *    it and puts it into the right queue.
 * 6) migration thread up()s the semaphore.
 * 7) we wake up and the migration is done.
 */
     code:
     if (migrate_task(p, any_online_cpu(*new_mask), &req)) {
        /* Need help from migration thread: drop lock and wait. */
        task_rq_unlock(rq, &flags);
        wake_up_process(rq->migration_thread);
        wait_for_completion(&req.done);
        tlb_migrate_finish(p->mm);
        return 0;

 /*
 * migration_thread - this is a highprio system thread that performs
 * thread migration by bumping thread off CPU then 'pushing' onto
 * another runqueue.
 */
static int migration_thread(void *data)
=>static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)