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https://issues.apache.org/jira/browse/YARN-1024?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13750286#comment-13750286
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Sandy Ryza commented on YARN-1024:
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bq. It seems to me that the only time you'd want a YCU value that's not -1 is
when you're running a thread that uses less than 100% of the CPU. Is that a
correct statement?
That's correct. This is common for data-intensive tasks that can be more
I/O-bound than CPU-bound.
bq. As an end user, how do I know what YCU value is reasonable for my job?
I think selecting the right value is an inherently difficult task. I think we
would expect different users with different amounts of technical proficiency to
do it in different ways. Something like:
* Simple: Use the default value on the cluster.
* Intermediate: Notice your tasks are running too slow and increase YCUs. Or
notice your tasks aren't getting scheduled enough and decrease them.
* Advanced: Do the thing with top.
> Define a virtual core unambigiously
> -----------------------------------
>
> Key: YARN-1024
> URL: https://issues.apache.org/jira/browse/YARN-1024
> Project: Hadoop YARN
> Issue Type: Improvement
> Reporter: Arun C Murthy
> Assignee: Arun C Murthy
> Attachments: CPUasaYARNresource.pdf
>
>
> We need to clearly define the meaning of a virtual core unambiguously so that
> it's easy to migrate applications between clusters.
> For e.g. here is Amazon EC2 definition of ECU:
> http://aws.amazon.com/ec2/faqs/#What_is_an_EC2_Compute_Unit_and_why_did_you_introduce_it
> Essentially we need to clearly define a YARN Virtual Core (YVC).
> Equivalently, we can use ECU itself: *One EC2 Compute Unit provides the
> equivalent CPU capacity of a 1.0-1.2 GHz 2007 Opteron or 2007 Xeon processor.*
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