Question

What is the difference between a process that is ready and a process that is waiting?

Short answer

A ready process waits for CPU time, while a waiting process waits for an external event to occur.

Step-by-step solution

Understand the Process Life Cycle

To understand the difference between a ready process and a waiting process, we first need to know the different states a process can be in during its life cycle. The main process states include: New, Ready, Running, Waiting (or Blocked), and Terminated. Each state has specific reasons and conditions for its existence.

Explain the Ready State

A process in the 'Ready' state is one that has been loaded into memory and is awaiting execution by the CPU. It has all necessary resources and conditions satisfied except the CPU time. Processes queue up in the ready state to be scheduled for execution.

Explain the Waiting State

A process in the 'Waiting' state (also known as Blocked state) is one that cannot continue execution until some external event occurs, such as the completion of an I/O operation, the availability of a resource, or a signal from another process. It relinquishes the CPU until its condition for execution is met.

Highlight the Key Difference

The key difference between a ready and a waiting process can be summarized based on their hold on CPU time. A ready process is waiting for CPU availability to proceed, while a waiting process is reliant on an external event/resource condition and does not need CPU time until the event is resolved.

Key concepts

Process Scheduling

Process scheduling is a key function of an operating system that ensures efficient CPU utilization. It involves deciding which process runs at any given time.
Scheduling helps maintain balance and prioritize tasks in a multi-tasking environment.

• **First,** the scheduler keeps track of processes in the system.
  
• **Second,** it uses algorithms to determine the execution order of processes in the ready state.
  
• **Finally,** by efficiently managing process execution, scheduling ensures that the system performs optimally.

Please note, process scheduling can be preemptive or non-preemptive:

• Preemptive scheduling allows processes to be interrupted and suspended to ensure that no single process hogs the CPU.
• Non-preemptive scheduling, on the other hand, executes a process until completion unless it is voluntarily relinquished.

This strategic allocation is crucial for resources optimization and in minimizing wait time for processes. It ultimately affects the system's responsiveness and overall throughput.

Process Life Cycle

The process life cycle outlines the journey of a process from creation to completion. It navigates through different states which affect its control over CPU time and resource allocation.
Here are the general stages of the process life cycle:

• **New** - The state when a process is being created.
  
• **Ready** - Here, the process has all resources except CPU time. It waits to be scheduled for execution.
  
• **Running** - In this state, the process operates under the CPU's control, executing its instructions.
  
• **Waiting (Blocked)** - A situation where a process waits for an external event, like I/O operations, before proceeding.
  
• **Terminated** - The final state occurs when the process completes or is terminated.
  

Understanding these states is essential, as it determines the process control block's movement and influences how the operating system manages tasks.
The operating system must efficiently transition processes between these states to maximize performance and minimize downtime of the CPU.

CPU Management

CPU management is about directing and overseeing the critical resource of CPU time distribution among processes.
This involves strategies to maximize process effectiveness and system efficiency. Here’s how:

• **Managing CPU Queues:** Processes queue up for CPU access. Efficient queue management ensures processes move smoothly from ready to execution.
  
• **Resource Allocation:** CPU management must ensure that resources are fairly and efficiently distributed. No process should monopolize CPU time.
  
• **Process Prioritization and Clocks:** Processes may be ranked in priority, allowing critical ones precedence. Time clocks can limit how long a process holds CPU resources.
  

By focusing on proper CPU management, operating systems can prevent bottlenecks. They ensure that the system is robust, with high throughput and low wait time for processes.
It's an essential operational aspect that allows for simultaneous process executions and maintains system balance.