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Posted to commits@cassandra.apache.org by "Matt Stump (JIRA)" <ji...@apache.org> on 2014/09/15 20:15:35 UTC

[jira] [Created] (CASSANDRA-7938) Releases prior to 2.1 gratuitously invalidate buffer cache

Matt Stump created CASSANDRA-7938:
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             Summary: Releases prior to 2.1 gratuitously invalidate buffer cache
                 Key: CASSANDRA-7938
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7938
             Project: Cassandra
          Issue Type: Bug
          Components: Core
            Reporter: Matt Stump


RandomAccessReader gratuitously invalidates the buffer cache in releases prior to 2.1. 

Additionally, Linux 3.X kernels spend 30% of CPU time in book keeping for the invalidated pages as captured by CPU flame graphs.

fadvise DONT_NEED should never be called for files other than the commit log segments. 

https://github.com/apache/cassandra/blob/cassandra-2.1/src/java/org/apache/cassandra/io/util/RandomAccessReader.java#L168



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