[run_perf] Replace usage of numpy with python3 statistics package

R=machenbach@chromium.org,liviurau@chromium.org,alexschulze@chromium.org

Bug: v8:12610
Change-Id: I24a1af48bf7a748e06c719439fb368ad75dd0160
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3448377
Auto-Submit: Tamer Tas <tmrts@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Tamer Tas <tmrts@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79013}

tools/run_perf.py

@@ -119,13 +119,21 @@ import sys
 import time
 import traceback
 
-import numpy
-
 from testrunner.local import android
 from testrunner.local import command
 from testrunner.local import utils
 from testrunner.objects.output import Output, NULL_OUTPUT
 
+from math import sqrt
+# NOTE: added import here to prevent breakages during the py2/3 migration,
+# once we enable python3 only, we can move the import up
+try:
+  from numpy import mean
+  from numpy import std as stdev
+except ImportError:
+  from statistics import mean, stdev
+
+
 # for py2/py3 compatibility
 try:
   basestring       # Python 2
@@ -265,11 +273,11 @@ class ResultTracker(object):
       return False
 
     logging.debug('  Results: %d entries', len(results))
-    mean = numpy.mean(results)
-    mean_stderr = numpy.std(results) / numpy.sqrt(len(results))
-    logging.debug('  Mean: %.2f, mean_stderr: %.2f', mean, mean_stderr)
-    logging.info('>>> Confidence level is %.2f', mean / (1000.0 * mean_stderr))
-    return confidence_level * mean_stderr < mean / 1000.0
+    avg = mean(results)
+    avg_stderr = stdev(results) / sqrt(len(results))
+    logging.debug('  Mean: %.2f, mean_stderr: %.2f', avg, avg_stderr)
+    logging.info('>>> Confidence level is %.2f', avg / (1000.0 * avg_stderr))
+    return confidence_level * avg_stderr < avg / 1000.0
 
   def __str__(self):  # pragma: no cover
     return json.dumps(self.ToDict(), indent=2, separators=(',', ': '))