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https://issues.apache.org/jira/browse/HDFS-2465?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13137718#comment-13137718
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Eli Collins commented on HDFS-2465:
-----------------------------------
bq. I don't think so. HDFS doesn't really do readahead except for filling up
the TCP window
I was thinking that filling up the dfs packet is essentially readahead since
we'll read the whole 64kb (or whatever is configured) regardless of how much
the client asks for but yea in this context that's not relevant (eg HBase
won't issue such small reads).
+1 to your latest patch. (Nit: add spaces in "1024*1024" no need to generate a
new patch)
> Add HDFS support for fadvise readahead and drop-behind
> ------------------------------------------------------
>
> Key: HDFS-2465
> URL: https://issues.apache.org/jira/browse/HDFS-2465
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: data-node, performance
> Affects Versions: 0.23.0
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Attachments: hdfs-2465.txt, hdfs-2465.txt
>
>
> This is the HDFS side of HADOOP-7714. The initial implementation is heuristic
> based and should be considered experimental, as discussed in the parent JIRA.
> It should be off by default until better heuristics, APIs, and tuning
> experience is developed.
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