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Date: Tue, 18 Oct 2011 16:45:10 +0000 (UTC)
From: "Jonathan Ellis (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (CASSANDRA-3376) Track buffer cache hit rate
 with mincore
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    [ https://issues.apache.org/jira/browse/CASSANDRA-3376?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13129849#comment-13129849 ] 

Jonathan Ellis commented on CASSANDRA-3376:
-------------------------------------------

Note that we already did a JNA mincore wrapper for CASSANDRA-1902 (which did not end up getting committed, but the patches are still there).
                
> Track buffer cache hit rate with mincore
> ----------------------------------------
>
>                 Key: CASSANDRA-3376
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3376
>             Project: Cassandra
>          Issue Type: New Feature
>            Reporter: Jonathan Ellis
>            Priority: Minor
>              Labels: ponies
>
> We could use mincore on, say, 1% of reads to be able to report actual buffer cache hit rate.  This would be useful when troubleshooting slow reads, e.g., are reads to CF X slow because it's hitting disk, or because there are a lot of tombstones in the row?

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