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https://issues.apache.org/jira/browse/CASSANDRA-14466?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16499100#comment-16499100
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Ariel Weisberg commented on CASSANDRA-14466:
--------------------------------------------
Can we try something slightly different? What happens if you run without
O_DIRECT, but with read ahead set to 0 and the compressed chunk length set to
4kb, 8kb, and 16kb?
I think to really pass judgement on adding this feature we would need to do a
more apples to apples comparison.
Can you also provide the exact cassandra-stress invocation you used? Was it
using a uniform distribution or a cacheable distribution?
> Enable Direct I/O
> ------------------
>
> Key: CASSANDRA-14466
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14466
> Project: Cassandra
> Issue Type: New Feature
> Components: Local Write-Read Paths
> Reporter: Mulugeta Mammo
> Priority: Major
> Attachments: direct_io.patch
>
>
> Hi,
> JDK 10 introduced a new API for Direct IO that enables applications to bypass
> the file system cache and potentially improve performance. Details of this
> feature can be found at [https://bugs.openjdk.java.net/browse/JDK-8164900].
> This patch uses the JDK 10 API to enable Direct IO for the Cassandra read
> path. By default, we have disabled this feature; but it can be enabled using
> a new configuration parameter, enable_direct_io_for_read_path. We have
> conducted a Cassandra read-only stress test and measured a throughput gain of
> up to 60% on flash drives.
> The patch requires JDK 10 Cassandra Support -
> https://issues.apache.org/jira/browse/CASSANDRA-9608
> Please review the patch and let us know your feedback.
> Thanks,
> [^direct_io.patch]
>
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