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https://issues.apache.org/jira/browse/HADOOP-7714?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13122361#comment-13122361
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Todd Lipcon commented on HADOOP-7714:
-------------------------------------

Rather than adding the portable approach myself, without a non-Linux test 
environment to experiment on, I figured I would make the whole feature 
auto-disable when not available. The next iteration of the patch does a manual 
syscall so it works on RHEL5 now as well, though it seems to have actually 
harmed terasort performance by 10% or so in its current form.

I fully support someone who has a non-Linux system doing the experiments with 
fdatasync though :)
                
> 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: graphs.pdf, 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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