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From "Tsz Wo (Nicholas), SZE (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-7443) Add CRC32C as another DataChecksum implementation
Date Tue, 12 Jul 2011 10:10:59 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-7443?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13063801#comment-13063801

Tsz Wo (Nicholas), SZE commented on HADOOP-7443:

> ... The tables are taken from some Intel sample code under the BSD license, as attributed
in the LICENSE file in this diff.

Hi Todd, given a polynomial, it is very easy to generate the tables so that we don't have
to include the BSD license.  Let me generate the tables.

> Add CRC32C as another DataChecksum implementation
> -------------------------------------------------
>                 Key: HADOOP-7443
>                 URL: https://issues.apache.org/jira/browse/HADOOP-7443
>             Project: Hadoop Common
>          Issue Type: New Feature
>          Components: io, util
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>         Attachments: hadoop-7443.txt
> CRC32C is another checksum very similar to our existing CRC32, but with a different polynomial.
The chief advantage of this other polynomial is that SSE4.2 includes hardware support for
its calculation. HDFS-2080 is the umbrella JIRA which proposes using this new polynomial to
save substantial amounts of CPU.

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