Telemetry / Memory benchmark fix: Separate histograms for different tests.

build/android/pylib/perf_tests_helper.py

Index: build/android/pylib/perf_tests_helper.py
diff --git a/build/android/pylib/perf_tests_helper.py b/build/android/pylib/perf_tests_helper.py
index 44397c01058f8d9e310e5aea3c7872fa00621d54..872d2019d1f9e62c958e3c7814feea49487046b4 100644
--- a/build/android/pylib/perf_tests_helper.py
+++ b/build/android/pylib/perf_tests_helper.py
@@ -65,6 +65,28 @@ def _MeanAndStdDevFromList(values):
     value = values[0]
   return value, avg, sd
 
+def SubtractHistogram(histogram_json, start_histogram_json):

[marja, 2013/02/14 13:06:53]

And I moved this one away now.

+  """Subtracts a previous histogram from a histogram. Both parameters are json
+  serializations of histograms."""
+  histogram = json.loads(histogram_json)
+  start_histogram = json.loads(start_histogram_json)
+
+  start_histogram_buckets = dict()
+  for b in start_histogram['buckets']:
+    start_histogram_buckets[b['low']] = b['count']
+
+  new_buckets = []
+  for b in histogram['buckets']:
+    new_bucket = b
+    low = b['low']
+    if low in start_histogram_buckets:
+      new_bucket['count'] = b['count'] - start_histogram_buckets[low]
+    if new_bucket['count']:
+      new_buckets.append(new_bucket)
+  histogram['buckets'] = new_buckets
+  histogram['count'] -= start_histogram['count']
+
+  return json.dumps(histogram)
 
 def PrintPerfResult(measurement, trace, values, units, result_type='default',
                     print_to_stdout=True):