---

yaml
---
r: 72354
b: refs/heads/master
c: 8c66006
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: edaf420fdc122e7a42326fe39274c8b8c9b19d41
+refs/heads/master: 8c660065383976f09fbdae86c33448c8da643d4e

trunk/arch/x86/kernel/tsc_32.c

@@ -137,31 +137,37 @@ unsigned long native_calculate_cpu_khz(void)
 
 	local_irq_save(flags);
 
-	/* run 3 times to ensure the cache is warm */
+	/* run 3 times to ensure the cache is warm and to get an accurate reading */
 	for (i = 0; i < 3; i++) {
 		mach_prepare_counter();
 		rdtscll(start);
 		mach_countup(&count);
 		rdtscll(end);
+
+		/*
+		 * Error: ECTCNEVERSET
+		 * The CTC wasn't reliable: we got a hit on the very first read,
+		 * or the CPU was so fast/slow that the quotient wouldn't fit in
+		 * 32 bits..
+		 */
+		if (count <= 1)
+			continue;
+
+		/* cpu freq too slow: */
+		if ((end - start) <= CALIBRATE_TIME_MSEC)
+			continue;
+
+		/*
+		 * We want the minimum time of all runs in case one of them
+		 * is inaccurate due to SMI or other delay
+		 */
 		delta64 = min(delta64, (end - start));
 	}
-	/*
-	 * Error: ECTCNEVERSET
-	 * The CTC wasn't reliable: we got a hit on the very first read,
-	 * or the CPU was so fast/slow that the quotient wouldn't fit in
-	 * 32 bits..
-	 */
-	if (count <= 1)
-		goto err;
 
-	/* cpu freq too fast: */
+	/* cpu freq too fast (or every run was bad): */
 	if (delta64 > (1ULL<<32))
 		goto err;
 
-	/* cpu freq too slow: */
-	if (delta64 <= CALIBRATE_TIME_MSEC)
-		goto err;
-
 	delta64 += CALIBRATE_TIME_MSEC/2; /* round for do_div */
 	do_div(delta64,CALIBRATE_TIME_MSEC);