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

tools/telemetry/telemetry/util.py

Index: tools/telemetry/telemetry/util.py
diff --git a/tools/telemetry/telemetry/util.py b/tools/telemetry/telemetry/util.py
index db93bcf79cb22d8c54be83016febb60dae8fd84d..30ef414cf755cfbaf3bdd83efe71b510881b635d 100644
--- a/tools/telemetry/telemetry/util.py
+++ b/tools/telemetry/telemetry/util.py
@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 import inspect
+import json
 import socket
 import time
 
@@ -66,3 +67,26 @@ def GetAvailableLocalPort():
   tmp.close()
 
   return port
+
+def SubtractHistogram(histogram_json, baseline_json):

[nduca, 2013/02/12 18:33:15]

i'd rather this wasn't in telemetry. Histograms are chrome sepcific. You can
have a perf_lib util if you wanted...

[marja, 2013/02/13 16:09:30]

perf_test_helpers.py seems like a logical place, since it already has other
histogram funcs. Moved it there.

+  """Subtracts baseline from a histogram. Both histogram and baseline are json
+  serializations of histograms."""
+  histogram = json.loads(histogram_json)
+  baseline = json.loads(baseline_json)
+
+  baseline_buckets = dict()
+  for b in baseline['buckets']:
+    baseline_buckets[b['low']] = b['count']
+
+  new_buckets = []
+  for b in histogram['buckets']:
+    new_bucket = b
+    low = b['low']
+    if low in baseline_buckets:
+      new_bucket['count'] = b['count'] - baseline_buckets[low]
+    if new_bucket['count']:
+      new_buckets.append(new_bucket)
+  histogram['buckets'] = new_buckets
+  histogram['count'] -= baseline['count']
+
+  return json.dumps(histogram)