Yanqin Jin ab202e8d72 Add a new stats level to exclude tickers (#7329) ... Summary: Currently, application may pass a statistics object to db but later wants to reduce stats tracking overhead by setting stats level to kExceptHistogramOrTimers (the current lowest level). Tickers will still be incremented, causing up to 1% CPU. We can add a new lowest stats level `kExceptTickers` to disable ticker incrementing as well, thus reducing CPU cycles spent on tickers. Test Plan (devserver): ``` make check make clean DEBUG_LEVEL=0 make db_bench ./db_bench -perf_level=1 -stats_level=0 -statistics -benchmarks=fillseq,readrandom -duration=120 ``` Measure CPU util (%) before and after change: CPU util by rocksdb::RecordTick: 1.1 vs (<0.1) Pull Request resolved: https://github.com/facebook/rocksdb/pull/7329 Reviewed By: pdillinger Differential Revision: D23434014 Pulled By: riversand963 fbshipit-source-id: 72ff0f02a192ac476d4b0044b9f37fd4a22ff0d4		2020-09-04 23:25:03 -07:00
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rocksdb	Add a new stats level to exclude tickers (#7329)	2020-09-04 23:25:03 -07:00