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https://issues.apache.org/jira/browse/HADOOP-7714?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13119455#comment-13119455
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Todd Lipcon commented on HADOOP-7714:
-------------------------------------
I agree with all of the above - I did the lame 256KB heuristic here because
adding an open API flag would be impossible while keeping it protocol
compatible. In 0.23 we use protobufs for the xceiver protocol so it would be
easy to add such a flag in a non-breaking manner.
(to be clear, the patch here is not for commit - it's just a rough patch to
illustrate the idea and start validating some assumptions about how buffer
cache management affects things like hbase, block report speed, disk seeks
incurred in the shuffle, etc)
> Add support in native libs for OS buffer cache management
> ---------------------------------------------------------
>
> Key: HADOOP-7714
> URL: https://issues.apache.org/jira/browse/HADOOP-7714
> Project: Hadoop Common
> Issue Type: Bug
> Components: native
> Affects Versions: 0.24.0
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Attachments: hadoop-7714-20s-prelim.txt
>
>
> Especially in shared HBase/MR situations, management of the OS buffer cache
> is important. Currently, running a big MR job will evict all of HBase's hot
> data from cache, causing HBase performance to really suffer. However, caching
> of the MR input/output is rarely useful, since the datasets tend to be larger
> than cache and not re-read often enough that the cache is used. Having access
> to the native calls {{posix_fadvise}} and {{sync_data_range}} on platforms
> where they are supported would allow us to do a better job of managing this
> cache.
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