diff --git a/sys/x86/include/apicvar.h b/sys/x86/include/apicvar.h
--- a/sys/x86/include/apicvar.h
+++ b/sys/x86/include/apicvar.h
@@ -128,7 +128,9 @@
 #define IPI_PREEMPT     1
 #define IPI_HARDCLOCK   2
 #define	IPI_TRACE	3	/* Collect stack trace. */
-#define	IPI_BITMAP_LAST IPI_TRACE
+#define IPI_IDLE	4	/* Idle scheduler. */
+#define IPI_UNIDLE	5	/* Unidle scheduler. */
+#define	IPI_BITMAP_LAST IPI_UNIDLE
 #define IPI_IS_BITMAPED(x) ((x) <= IPI_BITMAP_LAST)
 
 #define	IPI_STOP	(APIC_IPI_INTS + 6)	/* Stop CPU until restarted. */
diff --git a/sys/x86/x86/mp_x86.c b/sys/x86/x86/mp_x86.c
--- a/sys/x86/x86/mp_x86.c
+++ b/sys/x86/x86/mp_x86.c
@@ -109,6 +109,8 @@
 u_long *ipi_invlcache_counts[MAXCPU];
 u_long *ipi_rendezvous_counts[MAXCPU];
 static u_long *ipi_hardclock_counts[MAXCPU];
+static u_long *ipi_idle_counts[MAXCPU];
+static u_long *ipi_unidle_counts[MAXCPU];
 #endif
 
 /* Default cpu_ops implementation. */
@@ -1369,6 +1371,18 @@
 #endif
 		hardclockintr();
 	}
+	if (ipi_bitmap & (1 << IPI_IDLE)) {
+#ifdef COUNT_IPIS
+		(*ipi_idle_counts[cpu])++;
+#endif
+		sched_do_idle(td, true);
+	}
+	if (ipi_bitmap & (1 << IPI_UNIDLE)) {
+#ifdef COUNT_IPIS
+		(*ipi_unidle_counts[cpu])++;
+#endif
+		sched_do_idle(td, false);
+	}
 	td->td_intr_frame = oldframe;
 	td->td_intr_nesting_level--;
 	if (ipi_bitmap & (1 << IPI_HARDCLOCK))
@@ -1771,6 +1785,10 @@
 		intrcnt_add(buf, &ipi_rendezvous_counts[i]);
 		snprintf(buf, sizeof(buf), "cpu%d:hardclock", i);
 		intrcnt_add(buf, &ipi_hardclock_counts[i]);
+		snprintf(buf, sizeof(buf), "cpu%d:idle", i);
+		intrcnt_add(buf, &ipi_idle_counts[i]);
+		snprintf(buf, sizeof(buf), "cpu%d:unidle", i);
+		intrcnt_add(buf, &ipi_unidle_counts[i]);
 	}
 }
 SYSINIT(mp_ipi_intrcnt, SI_SUB_INTR, SI_ORDER_MIDDLE, mp_ipi_intrcnt, NULL);