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https://issues.apache.org/jira/browse/YARN-2440?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14128843#comment-14128843
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Vinod Kumar Vavilapalli commented on YARN-2440:
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bq. As I mentioned before, I think most users would rather not use the
functionality proposed by this JIRA but instead setup peer cgroups for other
systems and set their relative cgroup shares appropriately. With this JIRA the
CPUs could sit idle despite demand from YARN containers, while a peer cgroup
setup allows CPU guarantees without idle CPUs if the demand is there.
[~jlowe], agree with the general philosophy. Though we are not yet there in
practice - datanodes, region servers don't yet live in cgroups in many sites.
Looking back at this JIRA, I see a good use for this. Having the overall YARN
limit will help ensure that apps' containers don't thrash cpu once we start
enabling support.
The other dimension to this is determinism w.r.t performance. Limiting to
allocated cores overall (as well as per container later) helps orgs run
workloads and reason about them deterministically. One of the examples is
benchmarking apps, but deterministic execution is a desired option beyond
benchmarks too.
> Cgroups should allow YARN containers to be limited to allocated cores
> ---------------------------------------------------------------------
>
> Key: YARN-2440
> URL: https://issues.apache.org/jira/browse/YARN-2440
> Project: Hadoop YARN
> Issue Type: Bug
> Reporter: Varun Vasudev
> Assignee: Varun Vasudev
> Attachments: apache-yarn-2440.0.patch, apache-yarn-2440.1.patch,
> apache-yarn-2440.2.patch, apache-yarn-2440.3.patch, apache-yarn-2440.4.patch,
> apache-yarn-2440.5.patch, apache-yarn-2440.6.patch,
> screenshot-current-implementation.jpg
>
>
> The current cgroups implementation does not limit YARN containers to the
> cores allocated in yarn-site.xml.
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