diff --git a/sys/kern/sched_4bsd.c b/sys/kern/sched_4bsd.c
index cefe4acc8e6c..a5768ec25765 100644
--- a/sys/kern/sched_4bsd.c
+++ b/sys/kern/sched_4bsd.c
@@ -37,6 +37,7 @@ __FBSDID("$FreeBSD$");
 
 #include "opt_hwpmc_hooks.h"
 #include "opt_sched.h"
+#include "opt_kdtrace.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -61,6 +62,12 @@ __FBSDID("$FreeBSD$");
 #include <sys/pmckern.h>
 #endif
 
+#ifdef KDTRACE_HOOKS
+#include <sys/dtrace_bsd.h>
+int				dtrace_vtime_active;
+dtrace_vtime_switch_func_t	dtrace_vtime_switch_func;
+#endif
+
 /*
  * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in
  * the range 100-256 Hz (approximately).
@@ -962,6 +969,16 @@ sched_switch(struct thread *td, struct thread *newtd, int flags)
 #endif
                 /* I feel sleepy */
 		lock_profile_release_lock(&sched_lock.lock_object);
+#ifdef KDTRACE_HOOKS
+		/*
+		 * If DTrace has set the active vtime enum to anything
+		 * other than INACTIVE (0), then it should have set the
+		 * function to call.
+		 */
+		if (dtrace_vtime_active)
+			(*dtrace_vtime_switch_func)(newtd);
+#endif
+
 		cpu_switch(td, newtd, td->td_lock);
 		lock_profile_obtain_lock_success(&sched_lock.lock_object,
 		    0, 0, __FILE__, __LINE__);
diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c
index 7fe80afa1449..172f41aa58a5 100644
--- a/sys/kern/sched_ule.c
+++ b/sys/kern/sched_ule.c
@@ -39,6 +39,7 @@
 __FBSDID("$FreeBSD$");
 
 #include "opt_hwpmc_hooks.h"
+#include "opt_kdtrace.h"
 #include "opt_sched.h"
 
 #include <sys/param.h>
@@ -69,6 +70,12 @@ __FBSDID("$FreeBSD$");
 #include <sys/pmckern.h>
 #endif
 
+#ifdef KDTRACE_HOOKS
+#include <sys/dtrace_bsd.h>
+int				dtrace_vtime_active;
+dtrace_vtime_switch_func_t	dtrace_vtime_switch_func;
+#endif
+
 #include <machine/cpu.h>
 #include <machine/smp.h>
 
@@ -1823,6 +1830,17 @@ sched_switch(struct thread *td, struct thread *newtd, int flags)
 #endif
 		lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object);
 		TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
+
+#ifdef KDTRACE_HOOKS
+		/*
+		 * If DTrace has set the active vtime enum to anything
+		 * other than INACTIVE (0), then it should have set the
+		 * function to call.
+		 */
+		if (dtrace_vtime_active)
+			(*dtrace_vtime_switch_func)(newtd);
+#endif
+
 		cpu_switch(td, newtd, mtx);
 		/*
 		 * We may return from cpu_switch on a different cpu.  However,