Index: sys/amd64/amd64/tsc.c
===========================================================================
--- sys/amd64/amd64/tsc.c	2005/11/29 01:00:18	#7
+++ sys/amd64/amd64/tsc.c	2005/11/29 01:00:18
@@ -128,3 +128,15 @@
 {
 	return (rdtsc());
 }
+
+void
+tsc_DELAY(int n)
+{
+	uint64_t start, end, now;
+
+	start = rdtsc();
+	end = start + (tsc_freq * n) / 1000000;
+	do {
+		now = rdtsc();
+	} while (now < end || (now > start && end < start));
+}
Index: sys/amd64/include/clock.h
===========================================================================
--- sys/amd64/include/clock.h	2005/11/29 01:00:18	#7
+++ sys/amd64/include/clock.h	2005/11/29 01:00:18
@@ -37,6 +37,7 @@
 int	sysbeep(int pitch, int period);
 void	init_TSC(void);
 void	init_TSC_tc(void);
+void	tsc_DELAY(int);
 
 #endif /* _KERNEL */
 
Index: sys/amd64/isa/clock.c
===========================================================================
--- sys/amd64/isa/clock.c	2005/11/29 01:00:18	#25
+++ sys/amd64/isa/clock.c	2005/11/29 01:00:18
@@ -269,7 +272,13 @@
 	int getit_calls = 1;
 	int n1;
 	static int state = 0;
+#endif
 
+	if (tsc_freq != 0 && !tsc_is_broken) {
+		tsc_DELAY(n);
+		return;
+	}
+#ifdef DELAYDEBUG
 	if (state == 0) {
 		state = 1;
 		for (n1 = 1; n1 <= 10000000; n1 *= 10)