Function sched_throw

freebsd/kern/sched_ule.c:2892–2928

* A CPU is entering for the first time or a thread is exiting. */

 * A CPU is entering for the first time or a thread is exiting.
 */
void
sched_throw(struct thread *td)
{
	struct thread *newtd;
	struct tdq *tdq;

	if (__predict_false(td == NULL)) {
#ifdef SMP
		PCPU_SET(sched, DPCPU_PTR(tdq));
#endif
		/* Correct spinlock nesting and acquire the correct lock. */
		tdq = TDQ_SELF();
		TDQ_LOCK(tdq);
		spinlock_exit();
		PCPU_SET(switchtime, cpu_ticks());
		PCPU_SET(switchticks, ticks);
		PCPU_GET(idlethread)->td_lock = TDQ_LOCKPTR(tdq);
	} else {
		tdq = TDQ_SELF();
		THREAD_LOCK_ASSERT(td, MA_OWNED);
		THREAD_LOCKPTR_ASSERT(td, TDQ_LOCKPTR(tdq));
		tdq_load_rem(tdq, td);
		td->td_lastcpu = td->td_oncpu;
		td->td_oncpu = NOCPU;
		thread_lock_block(td);
	}
	newtd = choosethread();
	spinlock_enter();
	TDQ_UNLOCK(tdq);
	KASSERT(curthread->td_md.md_spinlock_count == 1,
	    ("invalid count %d", curthread->td_md.md_spinlock_count));
	/* doesn't return */
	if (__predict_false(td == NULL))
		cpu_throw(td, newtd);		/* doesn't return */
	else
		cpu_switch(td, newtd, TDQ_LOCKPTR(tdq));
}

/*
 * This is called from fork_exit().  Just acquire the correct locks and