[jira] [Updated] (CASSANDRA-8150) Simplify and enlarge new heap calculation

["Matt Stump (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-8150?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Matt Stump updated CASSANDRA-8150:
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    Attachment: upload.png

Just to emphasize the point I just got word of another unrelated customer that rolled out the changes. Here is a graph of their GC activity. Additionally, write latency was cut in half.

> Simplify and enlarge new heap calculation
> -----------------------------------------
>
>                 Key: CASSANDRA-8150
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8150
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Config
>            Reporter: Matt Stump
>            Assignee: Brandon Williams
>         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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