CS457 - System Performance Evaluation - Winter 2010

Public Service Announcements

  1. Office hours for assignment 1. (DC3549)
  2. Assignment 1 revised.
  3. PDF in the notes.

Lecture 7 - Little's Law (pdf)

There are two ways to study the performance of systems

Little's Law, and the other results, are results of an operational analysis.

Reminder. Operational results depend on the assumption that the system is stable, and average out transient effects that occur when sudden changes occur in workload or system parameters.

Connecting the Stochastic and Operational Views

Stochastic model of interarrival times


  1. Population of users, N, goes to inifinity.
  2. Infinite limit is reached such that Np = \lambda is finite
  3. Users are independent of one another
  4. Request submission is independent of the number of requests already in the system.

Proof - Appendix of pdf



Applying Little's Law

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