[GitHub] yifeih commented on a change in pull request #23914: [SPARK-27009][TEST] Add Standard Deviation to benchmark results

[GitBox <gi...@apache.org>]

yifeih commented on a change in pull request #23914: [SPARK-27009][TEST] Add Standard Deviation to benchmark results
URL: https://github.com/apache/spark/pull/23914#discussion_r261368903
 
 

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 File path: core/src/test/scala/org/apache/spark/benchmark/Benchmark.scala
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 @@ -158,7 +159,8 @@ private[spark] class Benchmark(
     // scalastyle:on
     val best = runTimes.min
     val avg = runTimes.sum / runTimes.size
-    Result(avg / 1000000.0, num / (best / 1000.0), best / 1000000.0)
+    val stdev = math.sqrt(runTimes.map(time => math.pow(time - avg, 2)).sum / runTimes.size)
 
 Review comment:
   Ah ok, I agree with you on both. If there aren't enough runs, should we just put "N/A" then? 

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