Project for the Performance Evaluation of Computer Systems and Networks (MSc Computer Engineering at University of Pisa, A.Y. 2021-22), made by Riccardo Sagramoni, Niko Salamini and Fabrizio Lanzillo.
The aim of the project was to design and develop with Omnet++ 5.7 a simulator of a supermarket, then evaluate its performance in several meaningful scenarios.
The project was developed on Ubuntu 20.04.
A supermarket has n tills. Two policies can be enforced for checkout:
- Undistinguished tills: any customer can check out at any till.
- Quick-checkout tills: a percentage p of tills is reserved for customers whose shopping cart holds less than k items (k being the quick-checkout threshold).
In both cases, a customer queues up at the till with the smallest queue among those where (s)he is allowed to queue.
Consider the following workload: customer inter-arrival times are IID RVs (to be described later), their service demands (i.e., checkout times) are IID RV (to be described later). The percentage of quick-checkout tills can be varied (but stays constant in a single simulation), and so does k.
Compare the queueing and response time of the two options under a varying workload. More in detail, at least the following scenarios must be evaluated:
- Exponential distribution of interarrival times and service demands.
- Lognormal distribution of service demands.