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Posted to jira@arrow.apache.org by "Antoine Pitrou (Jira)" <ji...@apache.org> on 2022/06/18 10:13:00 UTC

[jira] [Commented] (ARROW-16850) [C++] Improve csv writer by copying data and delimiter separately

    [ https://issues.apache.org/jira/browse/ARROW-16850?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17555880#comment-17555880 ] 

Antoine Pitrou commented on ARROW-16850:
----------------------------------------

Interesting. This shows that sometimes performance can be counter-intuitive.

> [C++] Improve csv writer by copying data and delimiter separately
> -----------------------------------------------------------------
>
>                 Key: ARROW-16850
>                 URL: https://issues.apache.org/jira/browse/ARROW-16850
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: C++
>            Reporter: Yibo Cai
>            Assignee: Yibo Cai
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 1h 40m
>  Remaining Estimate: 0h
>
> Profiling csv writer with Arm Statistical Profiling Extension (SPE) reveals there is relatively high branch misprediction rate from {{memcpy}}, due to interleaving copying data field and delimiter which is very short(1 or 2 chars). Copying delimiter with specific code, {{memcpy}} only the data field improves performance significantly.



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