Little's Law
Thursday, February 18, 2010
9:13 AM
Little's Law
The reason the watermark analogy holds is "Little's Law"
A system is in steady state if the average number of requests leaving the system = the average number of requests coming in. 
Little's law relates
The average arrival rate λ (e.g., requests arriving per second) (average inter-arrival time is 1/λ)
The average waiting time in system W (e.g., seconds between request and response)
The average requests in system L (e.g., the number of requests received and awaiting service)
 If the system is in steady state, then L = λW. 