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https://issues.apache.org/jira/browse/CASSANDRA-8614?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14277185#comment-14277185
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Ariel Weisberg commented on CASSANDRA-8614:
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It seems like the fallback in JDK 8 is to a slicing table based implementation,
but it isn't the slicing by 8 algorithm. It was considered not enough better.
http://mail.openjdk.java.net/pipermail/aarch64-port-dev/2014-May/001113.html
http://people.linaro.org/~edward.nevill/crc32/crc32.patch
I wonder how safe it is to assume that hardware running C* will have it. It was
introduced in 2010 http://en.wikipedia.org/wiki/CLMUL_instruction_set There is
also the question of whether it is enabled in a virtualized environment.
I will benchmark the fallback option and see how it compares to PureJavaCRC32.
> 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
> Assignee: Benedict
> Labels: performance
> Attachments: 8614.patch, Sample.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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