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https://issues.apache.org/jira/browse/CASSANDRA-10403?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14937039#comment-14937039
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Jonathan Shook commented on CASSANDRA-10403:
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This statement carries certain assumptions about the whole system, which may
not be fair across the board. For example, buffer cache is a critical
consideration, but to a varying degree depending on how cache-friendly the
workload is. Further, the storage subsystem determines a very large part of how
much of a cache-miss penalty there is. So, prioritizing the cache at the
expense of the heap is not a sure win. Often it is not the right balance.
With system that have high concurrency, it is possible to scale up the
performance on the node as long as you can provide reasonable tunings to
effectively take advantage of available resources without critically
bottle-necking on one. For example, with systems that have higher effective IO
concurrency and IO bandwidth across many devices, you actually need higher GC
throughput in order to match the overall IO capacity of the system, from
storage subsystem all the way to the network stack.
This rationale has been evidenced in the field when we have made tuning
improvements with G1 in certain systems as an opportunistic test. My
explanation above is a probably a gross oversimplification, but it reflects
experience addressing GC throughput (and pauses, and phi, and hints, and load
shifting ... etc) issues.
> 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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