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https://issues.apache.org/jira/browse/CASSANDRA-3623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13176221#comment-13176221
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Vijay commented on CASSANDRA-3623:
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" Also I took a look at the doc you have attached and it looks like test for
10000 is broken because stress command line shows that you use -S 3000 instead
of 10000."
I will fix it.
"Also as I mentioned before - you test on the different nodes on the working
cluster, there are side factors that could be affecting test results. Can you
please explain why testing performance on the working cluster is a good idea?"
How do you know it is a working cluster? They are individual machine isolated
without any network access to any other machine. There isnt anything which is
been shared between those machines (They are VM's from the diffrent servers
than the results which i have ever published). I created this test in different
just to make a clean environment with cold cache (other option is to reset the
mmap which i dont want to do).
I know you have your doubts but I am not that bad ;)
> 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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