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Posted to commits@cassandra.apache.org by "Benedict (JIRA)" <ji...@apache.org> on 2015/01/14 01:26:34 UTC

[jira] [Commented] (CASSANDRA-8614) Select optimal CRC32 implementation at runtime

    [ https://issues.apache.org/jira/browse/CASSANDRA-8614?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14276261#comment-14276261 ] 

Benedict commented on CASSANDRA-8614:
-------------------------------------

Why not check "java.version"?

> Select optimal CRC32 implementation at runtime
> ----------------------------------------------
>
>                 Key: CASSANDRA-8614
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8614
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Ariel Weisberg
>              Labels: performance
>         Attachments: 8614.patch
>
>
> JDK 8 has support for an intrinsic for CRC32 that runs at 12-13 gigabytes/sec per core in my quick and dirty test. PureJavaCRC32 is < 800 megabytes/sec if I recall and it has a lookup table that evicts random cache lines every time it runs.
> In order to capture the benefit of that when it is available we can select a CRC32 implementation at startup in a static block.
> If JDK 8 is not what is running we can fall back to the existing PureJavaCRC32 implementation.



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