[jira] [Commented] (HBASE-21874) Bucket cache on Persistent memory

["Sean Busbey (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-21874?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16782042#comment-16782042 ] 

Sean Busbey commented on HBASE-21874:
-------------------------------------

Overall, docs of the {{hbase.bucketcache.ioengine}} config need to be updated to cover the addition of pmem. e.g.

* hbase-common/src/main/resources/hbase-default.xml
* src/main/asciidoc/_chapters/hbase-default.adoc
* src/main/asciidoc/_chapters/architecture.adoc

Since we're building off of the mmap implementation we should probably specifically call out that it's currently treated as non-persistent and e.g. {{hbase.bucketcache.persistent.path}} doesn't matter.

in BucketCache.java
{code}
+    } else if (ioEngineName.startsWith("pmem:")) {
+      return new PmemIOEngine(ioEngineName.substring(5), capacity);
     } else {
       throw new IllegalArgumentException(
           "Don't understand io engine name for cache- prefix with file:, files:, mmap: or offheap");
{code}

Update IAE text to include pmem.


> 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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