stack created HBASE-11323:
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Summary: BucketCache all the time!
Key: HBASE-11323
URL: https://issues.apache.org/jira/browse/HBASE-11323
Project: HBase
Issue Type: Sub-task
Reporter: stack
One way to realize the parent issue is to just enable bucket cache all the
time; i.e. always have offheap enabled. Would have to do some work to make it
drop-dead simple on initial setup (I think it doable).
So, upside would be the offheap upsides (less GC, less likely to go away and
never come back because of full GC when heap is large, etc.).
Downside is higher latency. In Nick's BlockCache 101 there is little to no
difference between onheap and offheap. In a basic compare doing scans and gets
-- details to follow -- I have BucketCache deploy about 20% less ops than LRUBC
when all incache and maybe 10% less ops when falling out of cache. I can't
tell difference in means and 95th and 99th are roughly same (more stable with
BucketCache). GC profile is much better with BucketCache -- way less.
BucketCache uses about 7% more user CPU.
More detail on comparison to follow.
I think the numbers disagree enough we should probably do the [~lhofhansl]
suggestion, that we allow you to have a table sit in LRUBC, something the
current bucket cache layout does not do.
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