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https://issues.apache.org/jira/browse/CASSANDRA-7882?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14122713#comment-14122713
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Benedict commented on CASSANDRA-7882:
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bq. or this happens with native gcc as well?
This will happen with all allocators (they need to manage the memory somehow),
but the profile will vary with each allocator and platform
bq. should we keep the start & end region-size configurable?
I think 1Kb -> 1Mb is more than enough to solve the problem. 1Kb is
considerably less than the general overhead for managing a table (might even be
sensible to start around 8Kb), so not a meaningful impact, and with logarithmic
scaling we're guaranteed good occupancy, so we're only going to have memory
pressure if there's genuine memory pressure.
I'm on the fence about if the logarithmic scaling should be configurable or
just always on. But it's likely sufficient to simply have an on/off config
parameter, if any.
If you want to have a crack at patching this, please do, and I'll review. We're
always keen to expand the contributor base and it isn't a high priority for the
core team right now.
> 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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