[jira] [Commented] (CASSANDRA-8150) Revaluate Default JVM tuning parameters

["Jeremy Hanna (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-8150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14572582#comment-14572582 ] 

Jeremy Hanna commented on CASSANDRA-8150:
-----------------------------------------

>From conversations with [~mstump] and [~atobey@datastax.com] about these settings, the only settings that are generally applicable are:

JVM_OPTS="$JVM_OPTS -XX:+PerfDisableSharedMem"
JVM_OPTS="$JVM_OPTS -XX:-UseBiasedLocking"

All other settings need to be tuned using A|B testing one at a time and specific to the environment and use case.

It was also noted that 8G heap and 2G newsize was a good general starting point.

> Revaluate Default JVM tuning parameters
> ---------------------------------------
>
>                 Key: CASSANDRA-8150
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8150
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Config
>            Reporter: Matt Stump
>            Assignee: Ryan McGuire
>         Attachments: upload.png
>
>
> It's been found that the old twitter recommendations of 100m per core up to 800m is harmful and should no longer be used.
> Instead the formula used should be 1/3 or 1/4 max heap with a max of 2G. 1/3 or 1/4 is debatable and I'm open to suggestions. If I were to hazard a guess 1/3 is probably better for releases greater than 2.1.



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