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https://issues.apache.org/jira/browse/HDFS-2080?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13052090#comment-13052090
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Kihwal Lee commented on HDFS-2080:
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This is awesome! I will review the patch carefully, but I have a couple of
questions for now.
* Did you compare the performance of "software" version with zlib? Just to make
sure we fallback to a better one. If zlib's crc32 doesn't perform significantly
better, using what we have will be simpler for supporting different polynomials.
* I did a bit of experiment about filling up the pipeline. When there is no
data dependency, I get 1.17 cycles/Qword. By dividing the buffer into three
chunks, I get about 1.6 - 1.7 cycles/Qword. This is before combining results
and processing remainder. I didn't tweak too much, so it might be possible to
make it a bit better. Although it's not in the patch, I am sure you have play
with it. Is there anything you found useful in making this work?
> Speed up DFS read path
> ----------------------
>
> Key: HDFS-2080
> URL: https://issues.apache.org/jira/browse/HDFS-2080
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs client
> Affects Versions: 0.23.0
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Fix For: 0.23.0
>
> Attachments: hdfs-2080.txt
>
>
> I've developed a series of patches that speeds up the HDFS read path by a
> factor of about 2.5x (~300M/sec to ~800M/sec for localhost reading from
> buffer cache) and also will make it easier to allow for advanced users (eg
> hbase) to skip a buffer copy.
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