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https://issues.apache.org/jira/browse/HADOOP-7714?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13121984#comment-13121984
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Robert Joseph Evans commented on HADOOP-7714:
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Congratulations 20% wall time speed up and a 35%/22% CPU time improvement is
huge. Do you have any metrics on what the OS is doing during the terrasort
both before and after your change? I want to understand a little bit better
what exactly is causing the speedup. I suspect that we were seeing a lot of
churn in the pages and the OS was dropping lots of pages that it then need
causing the disk to seek slowing down everything. I would love to see disk IO
usage and page churn data.
> 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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