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From "Jay Patel (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-7882) Memtable slab allocation should scale logarithmically to improve occupancy rate
Date Fri, 05 Sep 2014 09:43:29 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-7882?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14122734#comment-14122734
] 

Jay Patel commented on CASSANDRA-7882:
--------------------------------------

Sure. Pls. assign it to me. I think better to have a on/off option initially, and then we
can make it on by default if it is promising for all kind of use cases, not just high # of
tables.

> Memtable slab allocation should scale logarithmically to improve occupancy rate
> -------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-7882
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7882
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Jay Patel
>            Assignee: Jay Patel
>              Labels: performance
>             Fix For: 2.1.1
>
>
> CASSANDRA-5935 allows option to disable region-based allocation for on-heap memtables
but there is no option to disable it for off-heap memtables (memtable_allocation_type: offheap_objects).

> Disabling region-based allocation will allow us to pack more tables in the schema since
minimum of 1MB region won't be allocated per table. Downside can be more fragmentation which
should be controllable by using better allocator like JEMalloc.
> How about below option in yaml?:
> memtable_allocation_type: unslabbed_offheap_objects
> Thanks.



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