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https://issues.apache.org/jira/browse/ARROW-9842?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17310461#comment-17310461
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Yibo Cai commented on ARROW-9842:
---------------------------------
Some observation:
- Manually tweaking mm_movemask_epi8 can improve compare kernel performance for
numerical data by ~60%.
- Defer bitpacking with big chunks may hurt performance.
- The actual effect depends heavily on the generator function and compiler.
It's not easy to find a general approach to benefit all cases.
> [C++] Explore alternative strategy for Compare kernel implementation for
> better performance
> -------------------------------------------------------------------------------------------
>
> Key: ARROW-9842
> URL: https://issues.apache.org/jira/browse/ARROW-9842
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Wes McKinney
> Priority: Major
> Fix For: 5.0.0
>
> Attachments: movemask-in-chunks.diff, movemask.patch
>
>
> The compiler may be able to vectorize comparison options if the bitpacking of
> results is deferred until the end (or in chunks). Instead, a temporary
> bytemap can be populated on a chunk-by-chunk basis and then the bytemaps can
> be bitpacked into the output buffer. This may also reduce the code size of
> the compare kernels (which are actually quite large at the moment)
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