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From "Benedict (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-11452) Cache implementation using LIRS eviction for in-process page cache
Date Thu, 14 Apr 2016 11:57:25 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-11452?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15241025#comment-15241025
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Benedict commented on CASSANDRA-11452:
--------------------------------------

Also, just to clarify, I'm not proposing a random _eviction_, just a random selection of who
to compare against for _admission_ - the eviction candidate would still be the LRU.  Thus
the collision would always be removed within a short number of steps after reaching the LRU
spot, and ordinarily rapidly after.

It's also worth noting that a RNF whose average walk distance was only a little larger than
1 (so that it usually compared against the eviction candidate) would more than suffice - if
the chance of each distance was 1/4 of the prior distance, the average walk length would only
be 1.33, but it would still take only a few comparisons for the eviction to unblock, and a
few more for multiple such collisions to be resolved.

> Cache implementation using LIRS eviction for in-process page cache
> ------------------------------------------------------------------
>
>                 Key: CASSANDRA-11452
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11452
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Local Write-Read Paths
>            Reporter: Branimir Lambov
>            Assignee: Branimir Lambov
>
> Following up from CASSANDRA-5863, to make best use of caching and to avoid having to
explicitly marking compaction accesses as non-cacheable, we need a cache implementation that
uses an eviction algorithm that can better handle non-recurring accesses.



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