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https://issues.apache.org/jira/browse/HADOOP-9601?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13758643#comment-13758643
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Colin Patrick McCabe commented on HADOOP-9601:
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Thanks for that background about ARM, Trevor. My statement about ARM only
applied to earlier ARMs. Still, I think we can agree that if we're going to do
processor-specific stuff, we should at least identify it as such and avoid it
on the CPUs that don't support it. Most likely, we should just avoid unaligned
access altogether. I filed HADOOP-9934 to discuss this, since it seems like a
separate issue from this bug.
> Support native CRC on byte arrays
> ---------------------------------
>
> Key: HADOOP-9601
> URL: https://issues.apache.org/jira/browse/HADOOP-9601
> Project: Hadoop Common
> Issue Type: Improvement
> Components: performance, util
> Affects Versions: 3.0.0
> Reporter: Todd Lipcon
> Assignee: Gopal V
> Labels: perfomance
> Attachments: HADOOP-9601-bench.patch,
> HADOOP-9601-rebase+benchmark.patch, HADOOP-9601-trunk-rebase-2.patch,
> HADOOP-9601-trunk-rebase.patch, HADOOP-9601-WIP-01.patch,
> HADOOP-9601-WIP-02.patch
>
>
> When we first implemented the Native CRC code, we only did so for direct byte
> buffers, because these correspond directly to native heap memory and thus
> make it easy to access via JNI. We'd generally assumed that accessing byte[]
> arrays from JNI was not efficient enough, but now that I know more about JNI
> I don't think that's true -- we just need to make sure that the critical
> sections where we lock the buffers are short.
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