1.) in preemptive scheduling we prempt the currently executing process, in non preemptive scheduling we allow the current process to finish its CPU burst time... 2.) in preemptive scheduling the process is forcibly sent to waiting state when a process with higher priority comes to CPU, in non preeemptive scheduling the process at running state can not be forced to leave the CPU until it completes........
In preemptive multitasking scheduling processes , scheduler can interrupt one running process and and allocate CUP to another process without letting the complete the task of first process. Window 95 introduced preemptive scheduling and Mac also uses this scheduling process. Bharat Rawal
scheduling algorithm
the objective of multiprograming is to have some processs running at aal time,so as to maximizing cpu utillization .this process is called scheduling.
dynamic job shop scheduling is the scheduling of the machine it can processes different jobs at time. it switches from one job to another job. in real time process jobs are executed based on the time.
Preemptive scheduler reruns scheduling decision when process becomes ready. If the new process has priority over running process, the CPU preempts the running process and executes the new process. Non-preemptive scheduler only does scheduling decision when running process voluntarily gives up CPU. In effect, it allows every running process to finish its CPU burst.
System Management
System Management
the total time that staying in the queue that wait for process of each process.
Round robin is the scheduling algorithm that is utilized by the CPU, or central processing unit, during the execution of the process. It is specifically designed for time sharing systems.
turn around time is the difference of time between the time of arrival of process and time of dispatch of process or we can say the time of completion of process
First-Come, First-Serve (FCFS) scheduling is one of the simplest scheduling algorithms in the realm of operating systems, and its implementation offers a straightforward approach to process management. In FCFS scheduling, processes are executed in the order they arrive in the ready queue, essentially adhering to a first-in, first-out (FIFO) strategy. The fundamental principle behind FCFS is straightforward: the first process to request the CPU gets executed first, and subsequent processes have to wait until the CPU is available again. The mechanism of FCFS scheduling is simple to understand and implement. When a process enters the system, it gets placed in the ready queue. The CPU scheduler picks the process at the head of the queue for execution and allocates the CPU to this process. The process continues to execute until it either finishes or gets blocked for I/O or some other reason, at which point the CPU is allocated to the next process in the ready queue. This cycle continues until all processes are executed. FCFS is non-preemptive, meaning once the CPU is allocated to a process, it retains control of the CPU until it completes its execution or gets blocked for some reason. This characteristic simplifies the scheduler design, making FCFS an attractive choice for simple systems or batch processing environments where jobs are more or less independent of each other. However, FCFS scheduling has its set of drawbacks. It can lead to the "convoy effect," where short processes have to wait for a long process to complete, leading to suboptimal CPU utilization. The average waiting time under FCFS scheduling can be high if long processes arrive at the queue early. Moreover, FCFS does not prioritize processes based on their importance or urgency, which can be a significant limitation in scenarios where certain processes require immediate attention. Despite its limitations, the simplicity and ease of implementation of FCFS scheduling make it a viable choice in specific scenarios, especially in systems with minimal process management requirements or in batch processing environments. It serves as a foundation for understanding more complex scheduling algorithms and provides a clear illustration of how process scheduling works at a basic level. In a nutshell, FCFS scheduling is a fundamental, easy-to-implement scheduling algorithm that executes processes based on their arrival order, adhering to a non-preemptive, first-in, first-out strategy. While it may not be the most efficient or versatile scheduling algorithm, its simplicity makes it a useful stepping stone in the study of operating system scheduling algorithms, paving the way for understanding more advanced scheduling strategies.