Number of Servers

The number of servers in a queuing system can vary depending on the application and the level of service desired. In some cases, a single server may suffice, whereas, in others, multiple servers may be required to meet demand.

• Single-server queuing systems: These are the most fundamental type of queuing systems, and they are frequently used in simple applications such as retail stores or fast-food restaurants. Customers arrive and queue to be served by a single server in these systems.
• Multi-server queuing systems: Multi-server queuing systems on the other hand, are used in more complex applications where demand is high and more than one server is required to handle the workload. A call center with multiple agents to handle incoming calls is an example of this type of system. Customers are usually directed to an available server in a multi-server system, and the service time distribution is assumed to be the same across all servers.

Various methods, such as queuing analysis, simulation, and optimization techniques, can be used to determine the number of servers in a queuing system. The goal is typically to find the optimal number of servers that minimizes system costs (e.g., staff wages) while providing an acceptable level of service.

In general, there is no fixed set of processes that run on systems; thus, measuring the exact processing requirements of processes is impossible. We can, however, measure the distributions of CPU bursts and I/O bursts over the course of a process and derive a mathematical formula that identifies the probability of a specific CPU burst. The arrival rate of processes in the system can be approximated in the same way. The development of queuing theory, a branch of mathematics, resulted from the use of mathematical models for evaluating the performance of various systems. 

The fundamental model of queuing theories is the same as the model of a computer system. Each computer system is represented as a collection of servers such as CPUs and I/O devices, each with its own queue. The article focuses on discussing the Queuing System in Operating System.

The following topics will be discussed here:

1. Components of Queuing System
2. Number of Servers
3. Measures of Performance for Queuing Systems
4. Notation for Queues
5. Queue Discipline
6. Queuing Models

Let’s start discussing each of these topics in detail.