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Date: Mon, 15 Sep 2014 18:16:34 +0000 (UTC)
From: "Matt Stump (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
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Subject: [jira] [Updated] (CASSANDRA-7938) Releases prior to 2.0
 gratuitously invalidate buffer cache
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     [ https://issues.apache.org/jira/browse/CASSANDRA-7938?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Matt Stump updated CASSANDRA-7938:
----------------------------------
    Summary: Releases prior to 2.0 gratuitously invalidate buffer cache  (was: Releases prior to 2.1 gratuitously invalidate buffer cache)

> Releases prior to 2.0 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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