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David Capwell commented on CASSANDRA-16036: ------------------------------------------- The test performed was 11% read of slices on a clustering key, so 89% write; workload from prod. What I was in the CPU profiles was that the chunk cache was a good chunk of compaction and the read path, but not in a positive way. With compaction also populating the cache, it caused a constant churn from the cache, but all reads had to pay the cost for it. > Add flag to disable chunk cache and disable by defaul > ----------------------------------------------------- > > Key: CASSANDRA-16036 > URL: https://issues.apache.org/jira/browse/CASSANDRA-16036 > Project: Cassandra > Issue Type: Bug > Components: Legacy/Local Write-Read Paths > Reporter: David Capwell > Assignee: David Capwell > Priority: Normal > Fix For: 4.0-beta > > Attachments: Histogram-11.png > > > Chunk cache is enabled by default and doesn’t have a flag to disable without > impacting networking. In performance testing 4.0 against 3.0 I found that > reads were slower in 4.0 and after profiling found that the ChunkCache was > partially to blame; after disabling the chunk cache, read performance had > improved. > {code} > 40_w_cc-selects.hdr > #[Mean = 11.50063, StdDeviation = 13.44014] > #[Max = 482.41254, Total count = 316477] > #[Buckets = 25, SubBuckets = 262144] > 40_wo_cc-selects.hdr > #[Mean = 9.82115, StdDeviation = 10.14270] > #[Max = 522.36493, Total count = 317444] > #[Buckets = 25, SubBuckets = 262144] > {code} -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org