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https://issues.apache.org/jira/browse/HBASE-19357?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16282170#comment-16282170
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stack commented on HBASE-19357:
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Thanks for measuring again. Some questions.
This SSD or HDD?
bq. File mode cache with META and NS table data still on on heap LRU (with out
this patch) is have a lesser QPS (as expected) compared to LRU cache.
Can you say in another way? This is file-mode but with META data blocks onheap.
And it is 20% less QPS compared to all data blocks being onheap in LRU? The 20%
is general YCSB or PE loading? Not queries against META table only?
bq. So I am no longer having the concern of META data NOT in LRU cache even
when BC file mode is in use.
Seems like META lookups are about the same though we did not directly measure
the change in latency.
I'd say that lets deal w/ it as a distinct issue. File a task for BC file-mode
perf eval with particular attention to META data block latencies? Soln may not
even be caching META blocks onheap.
Thanks for doing the test.
> Bucket cache no longer L2 for LRU cache
> ---------------------------------------
>
> Key: HBASE-19357
> URL: https://issues.apache.org/jira/browse/HBASE-19357
> Project: HBase
> Issue Type: Sub-task
> Reporter: Anoop Sam John
> Assignee: Anoop Sam John
> Fix For: 2.0.0-beta-1
>
> Attachments: HBASE-19357.patch, HBASE-19357.patch,
> HBASE-19357_V2.patch, HBASE-19357_V3.patch, HBASE-19357_V3.patch
>
>
> When Bucket cache is used, by default we dont configure it as an L2 cache
> alone. The default setting is combined mode ON where the data blocks to
> Bucket cache and index/bloom blocks go to LRU cache. But there is a way to
> turn this off and make LRU as L1 and Bucket cache as a victim handler for L1.
> It will be just L2.
> After the off heap read path optimization Bucket cache is no longer slower
> compared to L1. We have test results on data sizes from 12 GB. The Alibaba
> use case was also with 12 GB and they have observed a ~30% QPS improve over
> the LRU cache.
> This issue is to remove the option for combined mode = false. So when Bucket
> cache is in use, data blocks will go to it only and LRU will get only index
> /meta/bloom blocks. Bucket cache will no longer be configured as a victim
> handler for LRU.
> Note : WHen external cache is in use, there only the L1 L2 thing comes. LRU
> will be L1 and external cache act as its L2. That make full sense.
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