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From "Todd Lipcon (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-7832) Using mincore to understand the effect of fadvise in the Linux page cache
Date Thu, 17 Nov 2011 21:33:51 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-7832?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13152350#comment-13152350

Todd Lipcon commented on HADOOP-7832:

nice analysis - makes sense. Another big benefit that I'm hoping to see from the fadvise stuff
is preventing flush-out of dentries and inodes. On clusters with lots of blocks, we see block
reports taking many minutes to generate (and incurring lots of seeks) because the FS metadata
gets evicted when MR jobs run.
> 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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