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https://issues.apache.org/jira/browse/CASSANDRA-3623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13193402#comment-13193402
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Vijay commented on CASSANDRA-3623:
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Hi Jonathan,
The env which i was testing was on XFS and NOOP scheduler (with JVM heap of
12/2). I also have a lot of memory (70G) to spare on those boxes...
Having said that I am not sure if it is was just me who will be benefited by
this patch... may be a 3rd opinion might help.
> use MMapedBuffer in CompressedSegmentedFile.getSegment
> ------------------------------------------------------
>
> Key: CASSANDRA-3623
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3623
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Affects Versions: 1.1
> Reporter: Vijay
> Assignee: Vijay
> Labels: compression
> Fix For: 1.1
>
> Attachments: 0001-MMaped-Compression-segmented-file-v2.patch,
> 0001-MMaped-Compression-segmented-file-v3.patch,
> 0001-MMaped-Compression-segmented-file.patch,
> 0002-tests-for-MMaped-Compression-segmented-file-v2.patch,
> 0002-tests-for-MMaped-Compression-segmented-file-v3.patch, CRC+MMapIO.xlsx,
> MMappedIO-Performance.docx
>
>
> CompressedSegmentedFile.getSegment seem to open a new file and doesnt seem to
> use the MMap and hence a higher CPU on the nodes and higher latencies on
> reads.
> This ticket is to implement the TODO mentioned in CompressedRandomAccessReader
> // TODO refactor this to separate concept of "buffer to avoid lots of read()
> syscalls" and "compression buffer"
> but i think a separate class for the Buffer will be better.
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