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https://issues.apache.org/jira/browse/CASSANDRA-6890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13949644#comment-13949644
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Joshua McKenzie commented on CASSANDRA-6890:
--------------------------------------------
Attaching some testing output. The survivor 0/1 are getting pretty well
hammered w/out mmap on there and the GC pattern for eden shows quite a bit more
pressure on the no mmap path. I'm thinking this is in keeping with the
performance results I saw where min, median etc. were all comparable (1 buffer
copy difference won't be measurable) but higher percentiles showed more and
more outliers.
> 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_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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