add tool that compares us_timer_* in stat dumps

tools/timer_diff.py

+import sys
+
+estimated_mhz = 0
+
+def tally(fn):
+    counts = []
+
+    for l in open(fn):
+        if ':' in l:
+            (key, value) = l.split(':')
+            if key == "estimated_cpu_mhz":
+                mhz = float(value)
+            if key.startswith('us_timer_'):
+                counts.append((key, int(value)))
+
+    return (counts, mhz)
+
+def main():
+    fn1, fn2 = sys.argv[1:3]
+    try:
+        diff_thresh = int(sys.argv[3])
+    except:
+        diff_thresh = 500 # differences under 500us aren't shown
+
+    (counts1, estimated_mhz1) = tally(fn1)
+    (counts2, estimated_mhz2) = tally(fn2)
+
+    global estimated_mhz
+
+    if estimated_mhz1 > estimated_mhz2:
+        # convert from mhz2 to mhz1
+        mhz1_factor = 1
+        mhz2_factor = estimated_mhz1 / estimated_mhz2
+        estimated_mhz = estimated_mhz1
+    else:
+        # convert from mhz1 to mhz2
+        mhz1_factor = estimated_mhz2 / estimated_mhz1
+        mhz2_factor = 1
+        estimated_mhz = estimated_mhz2
+
+
+    i1 = 0
+    i2 = 0
+    while i1 < len(counts1) or i2 < len(counts2):
+        count1 = 0
+        count2 = 0
+
+        name1 = "zzz"
+        name2 = "zzz"
+
+        if i1 < len(counts1):
+            name1 = counts1[i1][0]
+        if i2 < len(counts2):
+            name2 = counts2[i2][0]
+
+        if name1 < name2:
+            # the counter in name1 is missing from name2, so count2 is 0
+            count1 = counts1[i1][1] * mhz1_factor
+            i1 += 1
+        elif name1 > name2:
+            # the counter in name1 is missing from name1, so count1 is 0
+            count2 = counts2[i2][1] * mhz2_factor
+            i2 += 1
+        else:
+            count1 = counts1[i1][1] * mhz1_factor
+            count2 = counts2[i2][1] * mhz2_factor
+            i1 += 1
+            i2 += 1
+
+        if abs(count1 - count2) < diff_thresh:
+            pass # they're within threshold, do nothing
+        elif count2 > count1:
+            bad(format_msg(name1, count1, count2, estimated_mhz))
+        else: #if count1 > count2
+            good(format_msg(name1, count1, count2, estimated_mhz))
+
+def bad(msg):
+    print '\033[91m', msg, '\033[0m'
+
+def good(msg):
+    print '\033[92m', msg, '\033[0m'
+
+def format_msg(name, before, after, mhz):
+    return "%s, before %d, after %d, delta %d (approx %s)" % (name, before, after, after - before, format_delta(after - before))
+
+def format_delta(delta):
+    if abs(delta) > 1000000:
+        return "%5.2f sec" % (delta / 1000000,)
+    if abs(delta) > 1000:
+        return "%5.2f msec" % (delta / 1000,)
+    return "%5.2f usec" % (delta,)
+
+if __name__ == "__main__":
+    main()