Index: sys/sys/time.h
===================================================================
--- sys/sys/time.h	(revision 242942)
+++ sys/sys/time.h	(working copy)
@@ -58,6 +58,8 @@ struct bintime {
 extern int tc_timethreshold;
 extern struct bintime tick_bt;
 
+#define	TC_DEFAULTPERC		5
+
 #define FREQ2BT(freq, bt)                                               \
 {                                                                       \
         (bt)->sec = 0;                                                  \
Index: sys/kern/kern_tc.c
===================================================================
--- sys/kern/kern_tc.c	(revision 242942)
+++ sys/kern/kern_tc.c	(working copy)
@@ -120,9 +120,10 @@ SYSCTL_INT(_kern_timecounter, OID_AUTO, stepwarnin
     &timestepwarnings, 0, "Log time steps");
 
 int tc_timethreshold;
+int tc_timepercentage;
 struct bintime tick_bt;
-SYSCTL_INT(_kern, OID_AUTO, tc_timethreshold, CTLFLAG_RW, 
-    &tc_timethreshold, 0, "Precision threshold for timing measurements"); 
+SYSCTL_INT(_kern, OID_AUTO, tc_timepercentage, CTLFLAG_RW, 
+    &tc_timepercentage, 0, "Precision percentage tolerance"); 
 
 static void tc_windup(void);
 static void cpu_tick_calibrate(int);
@@ -1728,10 +1729,12 @@ inittimecounter(void *dummy)
 		tc_tick = (hz + 500) / 1000;
 	else
 		tc_tick = 1;
+	tick_rate = hz / tc_tick;
+	tc_timepercentage = 
+	    (tc_timepercentage == 0) ? TC_DEFAULTPERC : tc_timepercentage;
+	tc_timethreshold = (100 / tc_timepercentage) * (1000000000 / tick_rate);
+	FREQ2BT(tick_rate, &tick_bt);
 	p = (tc_tick * 1000000) / hz;
-	tc_timethreshold = 20 * imin(1000000000 / hz, 1000000);
-	tick_rate = imax(hz, tc_tick);
-	FREQ2BT(tick_rate, &tick_bt);
 	printf("Timecounters tick every %d.%03u msec\n", p / 1000, p % 1000);
 
 #ifdef FFCLOCK