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https://issues.apache.org/jira/browse/HDFS-12277?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16119251#comment-16119251
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Andrew Wang commented on HDFS-12277:
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Hi Michael, thanks for working on this. I think the current cumulativeTime 
behavior is intentional. If you want to add additional throughput-per-thread 
metrics, that'd be a fine addition.

It might also be interesting to consider histogram metrics, like YCSB. Since 
the NN is an in-memory system there won't be as much variability, but this 
would be a good way to check.

> NNThroughputBenchmark should use cumulativeTime to calculate ops per second.
> ----------------------------------------------------------------------------
>
>                 Key: HDFS-12277
>                 URL: https://issues.apache.org/jira/browse/HDFS-12277
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: benchmarks, tools
>            Reporter: Michael Han
>            Assignee: Michael Han
>            Priority: Minor
>         Attachments: HDFS-12277.000.patch, HDFS-12277.001.patch
>
>
> {{NNThroughputBenchmark$getOpsPerSecond}} is using {{elapsedTime}} to 
> calculate ops per second. {{elapsedTime}} is the time used to measure the 
> time from the start to the finish of the benchmark main thread, and it's also 
> the total execution time of the single slowest benchmark worker thread. To 
> measure ops per second, we should use the total execution time of all worker 
> threads, which is {{cumulativeTime}}. Otherwise, we could get bogus result, 
> e.g. given same load, the more client threads we have (controlled by 
> {{-threads}}), the larger ops per second the number would be, with the same 
> NN and its server side configurations.



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