[jira] [Comment Edited] (CASSANDRA-7882) Allow disabling slab allocation for off-heap memtables

["Jay Patel (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-7882?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14122602#comment-14122602 ] 

Jay Patel edited comment on CASSANDRA-7882 at 9/5/14 8:16 AM:
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I've added code for this in my local env, and done some testing. Reduction in allocated memory is significant with higher number of tables (1000s to 10s of thousands) in a cluster. By default region-based allocation should be always-on but providing this option will allow flexibility for packing more tables.

I'm fine if we should keep it undocumented like CASSANDRA-5935.


was (Author: pateljay3001):
I've added code for this in my loca env, and done some testing. Reduction in allocated memory is significant with higher number of tables (1000s to 10s of thousands) in a cluster. By default region-based allocation should be always-on but providing this option will allow flexibility for packing more tables.

I'm fine if we should keep it undocumented like CASSANDRA-5935.

> Allow disabling slab allocation for off-heap memtables
> ------------------------------------------------------
>
>                 Key: CASSANDRA-7882
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7882
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Jay Patel
>             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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