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https://issues.apache.org/jira/browse/HDFS-2080?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13056711#comment-13056711
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Todd Lipcon commented on HDFS-2080:
-----------------------------------
I don't think your inline asm is doing quite what you want. I don't know the
asm syntax well, but it seems you're calculating the crc at data[offset],
data[offset+1], and data[offset+2]. But, those have data dependencies between
them. The crc32cHardware64_3parallel code calculates three separate chunks (at
512-byte offsets from each other) pipelined together
> 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, 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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