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https://issues.apache.org/jira/browse/CASSANDRA-6890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13949416#comment-13949416
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Joshua McKenzie commented on CASSANDRA-6890:
--------------------------------------------

Initial testing indicates a performance regression.  Just commenting out / 
changing the type of SegmentedFile we're using is showing the #'s listed in my 
previous comment.  I'll be working on getting clarity as to why this is taking 
place before moving forward on actually submitting a patch to remove the 
functionality.

> Remove mmap'ed i/o from read path
> ---------------------------------
>
>                 Key: CASSANDRA-6890
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6890
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Joshua McKenzie
>            Assignee: Joshua McKenzie
>            Priority: Minor
>             Fix For: 3.0
>
>         Attachments: mmap_perf.txt
>
>
> Since we actively unmap unreferenced SSTR's and also copy data out of those 
> readers on the read path, the current memory mapped i/o is a lot of 
> complexity for very little payoff.  Clean out the mmapp'ed i/o on the read 
> path.



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