Coarse-Grain QoS-Aware Dynamic Instance Provisioning for Interactive Workload in the Cloud

Algorithm 3

Online estimation of 𝐶_𝐴.

(1) for  𝑖=1 to 𝐿  do

(2) Measure 𝜆_𝑖; {𝜆_𝑖 is the number of request arrivals in time window 𝑖.}

(3)  𝑡_𝑖=1/𝜆_𝑖; {Estimate the average inter-arrival time in time window 𝑖.}

(4)  𝐴←𝐴+𝜆_𝑖; {𝐴 logs the accumulative total number of request in this time slot.}

(5) end for

(6) 𝑡_𝑎=𝐿/𝐴; {Estimate the average inter-arrival times in the time slot.}

(7) 𝜎=∑^𝐿_𝑖=1𝜆_𝑖𝑡_𝑖−𝑡_𝑎²; {Estimate the standard deviation of inter-arrival time.}

(8) 𝐶_𝐴=𝜎/𝑡_𝑎;