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https://issues.apache.org/jira/browse/CASSANDRA-10403?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14936132#comment-14936132
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Jonathan Shook commented on CASSANDRA-10403:
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To be fair, m1.xlarge has less than 16GB of RAM, which still on the small side
for G1 effectiveness, although at some point between 14G and 24G you should
start seeing G1 provide more stability than CMS for GC saturating loads.
(Assuming you don't set the GC pause target down too low)
G1 should start to be the obvious choice when you run with more than about 24GB
and even more obviously with 32GB of heap. This might seem large, but if you
look at what businesses tend to deploy in data centers for bare metal, they
aren't just 32GB systems anymore. You'll often see 64, 128, or more GB of DRAM.
There are some other ec2 profiles which get up to this range, but they are
disproportionately more expensive.
So, tests that go up to 32G of heap on a system with 64GB of main memory are
really where the proof points are. Saturating loads are good too.
> Consider reverting to CMS GC on 3.0
> -----------------------------------
>
> Key: CASSANDRA-10403
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10403
> Project: Cassandra
> Issue Type: Improvement
> Components: Config
> Reporter: Joshua McKenzie
> Assignee: Paulo Motta
> Fix For: 3.0.0 rc2
>
>
> Reference discussion on CASSANDRA-7486.
> For smaller heap sizes G1 appears to have some throughput/latency issues when
> compared to CMS. With our default max heap size at 8G on 3.0, there's a
> strong argument to be made for having CMS as the default for the 3.0 release.
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