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https://issues.apache.org/jira/browse/CASSANDRA-6890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14026475#comment-14026475
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Jason Brown commented on CASSANDRA-6890:
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Hmm, are we sure we really want to do this before CASSANDRA-5863 is proven (or
even implemented)? The v1 patch is simple enough, but we are taking a known
performance hit against an unknown future payoff. How much simpler would
removing the mmap path make implementing CASSANDRA-5863? I can't imagine it'd
make that much of a difference?
Furthermore, if anyone is truly interested, I'll be talking about direct i/o
(O_DIRECT) at the 2014 NGCC.
> Standardize on a single read path
> ---------------------------------
>
> Key: CASSANDRA-6890
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6890
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Joshua McKenzie
> Assignee: Joshua McKenzie
> Labels: performance
> Fix For: 3.0
>
> Attachments: 6890_v1.txt, mmap_gc.jpg, mmap_jstat.txt, mmap_perf.txt,
> nommap_gc.jpg, nommap_jstat.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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