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From "Devaraj K (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-5764) NUMA awareness support for launching containers
Date Tue, 10 Jan 2017 23:23:58 GMT

    [ https://issues.apache.org/jira/browse/YARN-5764?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15816512#comment-15816512
] 

Devaraj K commented on YARN-5764:
---------------------------------

Thanks a lot [~leftnoteasy] for review and comments.

bq. What is the benefit to manually specify NUMA node? Since this is potentially complex for
end user to specify, I think it's better to directly read data from OS.
If the users want to share the NUMA resources in Node Manager machine for non-Yarn applications,
then users can specify what all numa nodes and each node capabilities can be used by Yarn
using this declaration. I understand there are configurations for specifying numa nodes, each
node memory and cpu's. But if we don't have provision for separating the NUMA resources for
Yarn, we could end up overlapping the resources used by Yarn and Non-Yarn applications.

bq. Does the changes work on platform other than Linux?
This patch works for Linux, if this approach is agreeable then I will update for windows as
well.

bq. I'm not quite sure about if this could happen: with this patch, YARN will launch process
one by one on each NUMA node to bind memory/cpu. Is it possible that there's another process
(outside of YARN) uses memory of NUMA node which causes processes launched by YARN failed
to bind or run?
I do think it could happen for memory, we can avoid this using the NUMA node topology declaration
for specifying the NUMA resources for Yarn applications. And also it would not be an issue
with the soft binding option which you mentioned in the below comment.

bq. This patch uses hard binding (get allocated resource on specified node or fail), is it
better to specify soft binding (prefer to allocate and can also accept other node). I think
soft binding should be default behavior to support NUMA.
I think it is a good suggestion, I can update the patch with this by changing '\--membind=nodes'
to '\--preferred=node'.

I will look forward for your further comments.

> NUMA awareness support for launching containers
> -----------------------------------------------
>
>                 Key: YARN-5764
>                 URL: https://issues.apache.org/jira/browse/YARN-5764
>             Project: Hadoop YARN
>          Issue Type: New Feature
>          Components: nodemanager, yarn
>            Reporter: Olasoji
>            Assignee: Devaraj K
>         Attachments: NUMA Awareness for YARN Containers.pdf, YARN-5764-v0.patch, YARN-5764-v1.patch
>
>
> The purpose of this feature is to improve Hadoop performance by minimizing costly remote
memory accesses on non SMP systems. Yarn containers, on launch, will be pinned to a specific
NUMA node and all subsequent memory allocations will be served by the same node, reducing
remote memory accesses. The current default behavior is to spread memory across all NUMA nodes.



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