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

["Ariel Weisberg (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-8614?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ariel Weisberg updated CASSANDRA-8614:
--------------------------------------
    Attachment: CRC32FactoryTest.java
                8614.patch

Compiles on Java 7 and when run on Java 8 you get the intrinsic. There is a test case to validate that the two checksums implementations behave the same.



> 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, CRC32FactoryTest.java
>
>
> 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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