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Lars Hofhansl commented on HBASE-11323: --------------------------------------- bq. I think the numbers disagree enough we should probably do the Lars Hofhansl suggestion, that we allow you to have a table sit in LRUBC, something the current bucket cache layout does not do. How is that to do after you spent some time with it. When I looked last (didn't spend a lot of time, though), it did not look entirely trivial. > BucketCache all the time! > ------------------------- > > Key: HBASE-11323 > URL: https://issues.apache.org/jira/browse/HBASE-11323 > Project: HBase > Issue Type: Sub-task > Components: io > Reporter: stack > Fix For: 0.99.0 > > > 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. -- This message was sent by Atlassian JIRA (v6.2#6252)