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From "Eric Evans (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-11940) Look into better default file_cache_size for 2.2
Date Wed, 15 Jun 2016 15:43:09 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-11940?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Eric Evans updated CASSANDRA-11940:
-----------------------------------
    Attachment: abnormal disk read throughput.png

> Look into better default file_cache_size for 2.2
> ------------------------------------------------
>
>                 Key: CASSANDRA-11940
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11940
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: T Jake Luciani
>            Assignee: T Jake Luciani
>             Fix For: 2.2.x
>
>         Attachments: abnormal disk read throughput.png
>
>
> CASSANDRA-8464 added support for mmapped decompression where in version <= 2.1 the
reads were all decompressed in standard heap buffers.
> Since the usage of the file_cache is based solely on the buffer capacity we should/can
make this much larger in 2.2 when the disk access mode is mmap.  
> The downside of this cache being too small is made worse by 8464 since the buffers are
mmapped/unmapped causing explicit page faults.



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