Index: head/sys/cddl/dev/lockstat/lockstat.c
===================================================================
--- head/sys/cddl/dev/lockstat/lockstat.c
+++ head/sys/cddl/dev/lockstat/lockstat.c
@@ -159,6 +159,8 @@
 
 	ASSERT(!lockstat_probemap[probe->lsp_probe]);
 
+	lockstat_enabled++;
+
 	lockstat_probemap[probe->lsp_probe] = id;
 #ifdef DOODAD
 	membar_producer();
@@ -182,6 +184,8 @@
 
 	ASSERT(lockstat_probemap[probe->lsp_probe]);
 
+	lockstat_enabled--;
+
 	lockstat_probemap[probe->lsp_probe] = 0;
 #ifdef DOODAD
 	lockstat_hot_patch();
Index: head/sys/kern/kern_lockstat.c
===================================================================
--- head/sys/kern/kern_lockstat.c
+++ head/sys/kern/kern_lockstat.c
@@ -45,7 +45,7 @@
 uint32_t lockstat_probemap[LS_NPROBES];
 void (*lockstat_probe_func)(uint32_t, uintptr_t, uintptr_t,
     uintptr_t, uintptr_t, uintptr_t);
-
+int lockstat_enabled = 0;
 
 uint64_t 
 lockstat_nsecs(void)
@@ -53,6 +53,9 @@
 	struct bintime bt;
 	uint64_t ns;
 
+	if (!lockstat_enabled)
+		return (0);
+
 	binuptime(&bt);
 	ns = bt.sec * (uint64_t)1000000000;
 	ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32;
Index: head/sys/sys/lockstat.h
===================================================================
--- head/sys/sys/lockstat.h
+++ head/sys/sys/lockstat.h
@@ -154,6 +154,7 @@
     uintptr_t arg2, uintptr_t arg3, uintptr_t arg4);
 extern lockstat_probe_func_t lockstat_probe_func;
 extern uint64_t lockstat_nsecs(void);
+extern int lockstat_enabled;
 
 #ifdef	KDTRACE_HOOKS
 /*