metrics are sufficient to parameterize our PDQ model Timestamp, Xdat, Nest, Sest, Rdat, Udat 1486771200000, 502.171674, 170.266663, 0.000912, 0.336740, 0.458120 1486771500000, 494.403035, 175.375000, 0.001043, 0.355975, 0.515420 1486771800000, 509.541751, 188.866669, 0.000885, 0.360924, 0.450980 1486772100000, 507.089094, 188.437500, 0.000910, 0.367479, 0.461700 1486772400000, 532.803039, 191.466660, 0.000880, 0.362905, 0.468860 1486772700000, 528.587722, 201.187500, 0.000914, 0.366283, 0.483160 1486773000000, 533.439054, 202.600006, 0.000892, 0.378207, 0.476080 1486773300000, 531.708059, 208.187500, 0.000909, 0.392556, 0.483160 1486773600000, 532.693783, 203.266663, 0.000894, 0.379749, 0.476020 1486773900000, 519.748550, 200.937500, 0.000895, 0.381078, 0.465260 ... Interval between Unix Timestamp rows is 300 seconds Little’s law (LL) gives relationships between above metrics: 1 Nest = Xdat × Rdat : macroscopic LL =⇒ thread concurrency 2 Udat = Xdat × Sest : microscopic LL =⇒ resource service times LL provides a consistency check of the data c 2019 Performance Dynamics How to Scale in the Cloud December 6, 2019 9 / 38