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https://issues.apache.org/jira/browse/HIVE-17220?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Prasanth Jayachandran reassigned HIVE-17220:
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> Bloomfilter probing in semijoin reduction is thrashing L1 dcache
> ----------------------------------------------------------------
>
> Key: HIVE-17220
> URL: https://issues.apache.org/jira/browse/HIVE-17220
> Project: Hive
> Issue Type: Bug
> Affects Versions: 3.0.0
> Reporter: Prasanth Jayachandran
> Assignee: Prasanth Jayachandran
>
> [~gopalv] observed perf profiles showing bloomfilter probes as bottleneck for
> some of the TPC-DS queries and resulted L1 data cache thrashing.
> This is because of the huge bitset in bloom filter that doesn't fit in any
> levels of cache, also the hash bits corresponding to a single key map to
> different segments of bitset which are spread out. This can result in K-1
> memory access (K being number of hash functions) in worst case for every key
> that gets probed because of locality miss in L1 cache.
> Ran a JMH microbenchmark to verify the same. Following is the JMH perf
> profile for bloom filter probing
> {code}
> Perf stats:
> --------------------------------------------------
> 5101.935637 task-clock (msec) # 0.461 CPUs utilized
> 346 context-switches # 0.068 K/sec
> 336 cpu-migrations # 0.066 K/sec
> 6,207 page-faults # 0.001 M/sec
> 10,016,486,301 cycles # 1.963 GHz
> (26.90%)
> 5,751,692,176 stalled-cycles-frontend # 57.42% frontend cycles
> idle (27.05%)
> <not supported> stalled-cycles-backend
> 14,359,914,397 instructions # 1.43 insns per cycle
> # 0.40 stalled cycles
> per insn (33.78%)
> 2,200,632,861 branches # 431.333 M/sec
> (33.84%)
> 1,162,860 branch-misses # 0.05% of all branches
> (33.97%)
> 1,025,992,254 L1-dcache-loads # 201.099 M/sec
> (26.56%)
> 432,663,098 L1-dcache-load-misses # 42.17% of all L1-dcache
> hits (14.49%)
> 331,383,297 LLC-loads # 64.952 M/sec
> (14.47%)
> 203,524 LLC-load-misses # 0.06% of all LL-cache
> hits (21.67%)
> <not supported> L1-icache-loads
> 1,633,821 L1-icache-load-misses # 0.320 M/sec
> (28.85%)
> 950,368,796 dTLB-loads # 186.276 M/sec
> (28.61%)
> 246,813,393 dTLB-load-misses # 25.97% of all dTLB
> cache hits (14.53%)
> 25,451 iTLB-loads # 0.005 M/sec
> (14.48%)
> 35,415 iTLB-load-misses # 139.15% of all iTLB
> cache hits (21.73%)
> <not supported> L1-dcache-prefetches
> 175,958 L1-dcache-prefetch-misses # 0.034 M/sec
> (28.94%)
> 11.064783140 seconds time elapsed
> {code}
> This shows 42.17% of L1 data cache misses.
> This jira is to use cache efficient bloom filter for semijoin probing.
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