[jira] [Resolved] (HIVE-10772) LLAP: perf dips with IO elevator disabled

["Sergey Shelukhin (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-10772?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sergey Shelukhin resolved HIVE-10772.
-------------------------------------
    Resolution: Cannot Reproduce

too unspecific

> LLAP: perf dips with IO elevator disabled
> -----------------------------------------
>
>                 Key: HIVE-10772
>                 URL: https://issues.apache.org/jira/browse/HIVE-10772
>             Project: Hive
>          Issue Type: Sub-task
>            Reporter: Sergey Shelukhin
>
> If Q1 TPCH is run 10 times in a row on the same cluster, with IO elevator,the perf stays relatively consistent (or improves due to JIT and stuff). Without, there's a large perf dip in the middle (usually dag #3 or so for me), then recovery.
> This dip is not caused directly by GC time, and at least in my case I cannot see any particular part becoming slower in YK profiles, or any obvious correlates. One can easily see tasks slow down from 3-7 to 10-30 seconds (up to 60 with slow HDFS reads). One thing that happens is that kernel CPU time goes up to 9-12% on all the daemons when the slowdown is "ramping up" and occuring, compared to usual 0-3% levels. I didn't investigate much where that comes from since this is not a mainline scenario.
> Still, interesting to learn what causes this.
> YK dumps provided upon request.



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