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https://issues.apache.org/jira/browse/HBASE-21874?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16769964#comment-16769964
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ramkrishna.s.vasudevan commented on HBASE-21874:
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bq. Can you point the exact place in the patch where you control this?
We need not control at the Java level. It will controlled at the OS level.
These devices are configured with DAX (Direct Access mode) at the OS level.
As said in the link - here we use the App Direct mode and not the memory mode.
Memory mode does not give us control as where the cache or the address space
could reside. It may be on DRAM or Pmem address space. But here we specifically
ask our cache to reside only on the Pmem area and once it is mapped in the Pmem
address space everything is transparent to us.
> Bucket cache on Persistent memory
> ---------------------------------
>
> Key: HBASE-21874
> URL: https://issues.apache.org/jira/browse/HBASE-21874
> Project: HBase
> Issue Type: New Feature
> Components: BucketCache
> Affects Versions: 3.0.0
> Reporter: ramkrishna.s.vasudevan
> Assignee: ramkrishna.s.vasudevan
> Priority: Major
> Fix For: 3.0.0
>
> Attachments: HBASE-21874.patch, HBASE-21874.patch,
> HBASE-21874_V2.patch, Pmem_BC.png
>
>
> Non volatile persistent memory devices are byte addressable like DRAM (for
> eg. Intel DCPMM). Bucket cache implementation can take advantage of this new
> memory type and can make use of the existing offheap data structures to serve
> data directly from this memory area without having to bring the data to
> onheap.
> The patch is a new IOEngine implementation that works with the persistent
> memory.
> Note : Here we don't make use of the persistence nature of the device and
> just make use of the big memory it provides.
> Performance numbers to follow.
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