diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c
--- a/sys/kern/sched_ule.c
+++ b/sys/kern/sched_ule.c
@@ -292,6 +292,7 @@
 	 */
 	u_char		tdq_ts_ticks;
 	int		tdq_id;		/* (c) cpuid. */
+	int		tdq_do_idle;
 	struct runq	tdq_runq;	/* (t) Run queue. */
 	char		tdq_name[TDQ_NAME_LEN];
 #ifdef KTR
@@ -1499,9 +1500,10 @@
 		cpu = sched_lowest(ccg, mask, pri, INT_MAX, ts->ts_cpu, r);
 		if (cpu >= 0)
 			SCHED_STAT_INC(pickcpu_intrbind);
-	} else
-	/* Search the LLC for the least loaded idle CPU we can run now. */
-	if (ccg != NULL) {
+	} else if (ccg != NULL) {
+		/*
+		 * Search the LLC for the least loaded idle CPU we can run now.
+		 */
 		cpu = sched_lowest(ccg, mask, max(pri, PRI_MAX_TIMESHARE),
 		    INT_MAX, ts->ts_cpu, r);
 		if (cpu >= 0)
@@ -1575,6 +1577,8 @@
 	struct thread *td;
 
 	TDQ_LOCK_ASSERT(tdq, MA_OWNED);
+	if (__predict_false(tdq->tdq_do_idle))
+		return (NULL); /* Return NULL for idle thread */
 	td = runq_choose_realtime(&tdq->tdq_runq);
 	if (td != NULL)
 		return (td);
@@ -2660,16 +2664,11 @@
 	thread_unlock(td);
 }
 
-void
-sched_preempt(struct thread *td)
+static void
+sched_preempt_locked(struct tdq *tdq, struct thread *td)
 {
-	struct tdq *tdq;
 	int flags;
 
-	SDT_PROBE2(sched, , , surrender, td, td->td_proc);
-
-	thread_lock(td);
-	tdq = TDQ_SELF();
 	TDQ_LOCK_ASSERT(tdq, MA_OWNED);
 	if (td->td_priority > tdq->tdq_lowpri) {
 		if (td->td_critnest == 1) {
@@ -2681,12 +2680,35 @@
 			return;
 		}
 		td->td_owepreempt = 1;
-	} else {
+	} else
 		tdq->tdq_owepreempt = 0;
-	}
 	thread_unlock(td);
 }
 
+void
+sched_preempt(struct thread *td)
+{
+	struct tdq *tdq;
+
+	SDT_PROBE2(sched, , , surrender, td, td->td_proc);
+
+	thread_lock(td);
+	tdq = TDQ_SELF();
+	sched_preempt_locked(tdq, td);
+}
+
+void
+sched_do_idle(struct thread *td, bool do_idle)
+{
+	struct tdq *tdq;
+
+	thread_lock(td);
+	tdq = TDQ_SELF();
+	TDQ_LOCK_ASSERT(tdq, MA_OWNED);
+	tdq->tdq_do_idle = do_idle;
+	sched_preempt_locked(tdq, td);
+}
+
 /*
  * Fix priorities on return to user-space.  Priorities may be elevated due
  * to static priorities in msleep() or similar.
@@ -2841,6 +2863,8 @@
 	tdq = TDQ_SELF();
 	TDQ_LOCK_ASSERT(tdq, MA_OWNED);
 	td = tdq_choose(tdq);
+	KASSERT(td != PCPU_GET(idlethread), ("sched_choose: idle thread "
+	    "explicitly returned; tdq_choose should return NULL instead"));
 	if (td != NULL) {
 		tdq_runq_rem(tdq, td);
 		tdq->tdq_lowpri = td->td_priority;
diff --git a/sys/sys/sched.h b/sys/sys/sched.h
--- a/sys/sys/sched.h
+++ b/sys/sys/sched.h
@@ -147,6 +147,7 @@
 void	sched_clock(struct thread *td, int cnt);
 void	sched_idletd(void *);
 void	sched_preempt(struct thread *td);
+void	sched_do_idle(struct thread *td, bool do_idle);
 void	sched_relinquish(struct thread *td);
 void	sched_rem(struct thread *td);
 void	sched_wakeup(struct thread *td, int srqflags);