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https://issues.apache.org/jira/browse/HADOOP-7832?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13152351#comment-13152351
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Todd Lipcon commented on HADOOP-7832:
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btw, another thing I think would be very interesting to look at: count the
percentage of write/flush calls on the DN that take longer than ~10ms. This
would serve to separate non-blocking writes (that just dirty pages) from
blocking writes (once the max dirty page ratio has been exceeded
(/proc/sys/vm/dirty_ratio)). Would be very interested to see if the
sync_file_range calls improve this metric. (again it's a theory but not
something I've verified)
> Using mincore to understand the effect of fadvise in the Linux page cache
> -------------------------------------------------------------------------
>
> Key: HADOOP-7832
> URL: https://issues.apache.org/jira/browse/HADOOP-7832
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: io, native, performance
> Reporter: Cristina L. Abad
> Priority: Minor
> Attachments: hadoop-7714-20s-205-mincore.txt
>
>
> This Jira adds a way to log the percentage of pages of a file that were on
> the Linux page cache (when the file is being opened) with the purpose of
> measuring the effect of issuing posix_fadvise (POSIX_FADV_DONTNEED) calls.
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