Andrew Kryczka ed0a4c93ef perf_context measure user bytes read ... Summary: With this PR, we can measure read-amp for queries where perf_context is enabled as follows: ``` SetPerfLevel(kEnableCount); Get(1, "foo"); double read_amp = static_cast<double>(get_perf_context()->block_read_byte / get_perf_context()->get_read_bytes); SetPerfLevel(kDisable); ``` Our internal infra enables perf_context for a sampling of queries. So we'll be able to compute the read-amp for the sample set, which can give us a good estimate of read-amp. Closes https://github.com/facebook/rocksdb/pull/2749 Differential Revision: D5647240 Pulled By: ajkr fbshipit-source-id: ad73550b06990cf040cc4528fa885360f308ec12		2017-08-18 11:43:33 -07:00
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rocksdb	perf_context measure user bytes read	2017-08-18 11:43:33 -07:00