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What kind of data structure is required to implement the round robin scheduling policy?
The circular queue data structure is required to implement the round robin scheduling policy. Round robin is similar to FCFS scheduling.
Explain with an example first come first serve scheduling algorithm?
By far the simplest CPU-scheduling algorithm is the first-come, first-served (FCFS) scheduling algorithm. With this scheme, the process that requests the CPU first is allocated the CPU first. The implementation of the FCFS policy is easily managed with a FIFO queue. When a process enters the ready queue, its PCB is linked onto the tail of the queue. When the CPU is free, it is allocated to the process at the head of the queue. The running process is then removed from the queue. The code for FCFS scheduling is simple to write and understand. The average waiting time under the FCFS policy, however, is often quite long. Consider the following set of processes that arrive at time 0, with the length of the CPU-burst time given in milliseconds:
What are the disadvantages of FCFS scheduling?
in fcfs scheduling there is a shortcoming that is if any rocess of maximum brust time is first ome. and after that many short burst time process come. then smaller pocesses have to wait for a long time untill the max brust time process complete their execution. in case of shortest job first it applied the method to give shortest t\burst time job to processer first.
What are the relationships between priority and FCFS of CPU scheduling algorithms?
this is my doubt about the non-preemptive priority scheduling. i m doing bachelor of engineering in IT and this question in end semester exam. the question is as follows:Assume you have the following jobs to be executed with one processor, with the jobs arriving in the order listed here:Process Burst Time PriorityP1 80 5P2 20 1P3 10 3P4 20 2P5 50 4Suppose the system uses priority scheduling. Draw Gantt chart and calculate average waiting time for the processes.My doubt is:suppose if we were to use non-preemptive priority scheduling, the question says the jobs arriving in the order listed, so as per the order P1 will arrive first so it will get the CPU first and in non-preemptive once a job gets CPU it will not leave CPU till the process finishes, then as per the order P2 will come and same thing repeats.... so it acts like FCFS scheduling and priority is of no use here. But my lecturer says we have to follow the priority and P2 will come first, but the line the jobs arriving in the order listed is still not letting me agree with my lecturer. Can anyone help out?
What would be the effect using the FCFS scheme if the running process got stuck in an infinite CPU loop?
In FCFS the processes are in served by the order they arrive and each process will not start until the served process is finished, so if any of the processes got stuck in an infinite CPU loop the whole system will stop and hang.
How do you do fcfs program in easy method using java?
import javax.swing.*; import java.awt.*; import java.awt.event.*; class fcfs extends JFrame implements ActionListener { JButton jb[] = new JButton[3]; JTextField jt1[],jt2[]; JLabel jl[],jl1,jl2,jl3; JPanel jp,jp1; Container con; int k,p; String str[] = {"SUBMIT","RESET","EXIT"}; String str1[] = {"Process"," AT","ST","WT","FT","TAT","NTAT"}; public fcfs() { super("fcfs scheduling algoritham"); con = getContentPane(); k= Integer.parseInt(JOptionPane.showInputDialog("Enter number of process")); jl1 = new JLabel("Process"); jl2 = new JLabel("Arival Time"); jl3 = new JLabel("Service Time"); jl = new JLabel[k]; jt1 = new JTextField[k]; jt2 = new JTextField[k]; for(int i=0;i<k;i++) { jl[i] = new JLabel("process"+(i+1)); jt1[i] = new JTextField(10); jt2[i] = new JTextField(10); } for(int i=0;i<3;i++) { jb[i] = new JButton(str[i]); } con.setLayout(new GridLayout(k+2,3)); con.add(jl1); con.add(jl2); con.add(jl3); int l=0; for(int i=0;i<k;i++) { con.add(jl[l]); con.add(jt1[l]); con.add(jt2[l]); l++; } l=0; for(int i=0;i<3;i++) { con.add(jb[l]); jb[l].addActionListener(this); l++; } }//end of constructor public void actionPerformed(ActionEvent ae) { int FT[] = new int[k]; int WT[] = new int[k]; int TAT[] = new int[k]; float NTAT[] = new float[k]; float sum=0; float avg; JPanel main = new JPanel(); main.setLayout(new BorderLayout()); jp = new JPanel(); jp1 = new JPanel(); jp.setLayout(new GridLayout(k+1,7)); jp1.setLayout(new FlowLayout()); if(ae.getSource() jb[1]) { setVisible(false); fcfs window = new fcfs(); window.setSize(400,300); window.setVisible(true); window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } }//END ACTION PERFORMED public static void main(String[] args) { fcfs window = new fcfs(); window.setSize(400,300); window.setVisible(true); window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); }//end main }//end class
Advantages and disadvantages of first come first serve scheduling?
First-come, first-served (FCFS) - sometimes first-in, first-served and first-come, first choice - is a service policy whereby the requests of customers or clients are attended to in the order that they arrived, without other biases or preferences. The policy can be employed when processing sales orders, in determining restaurant seating, on a taxi stand, etc. In Western society, it is the standard policy for the processing of most queues in which people wait for a service or two.
What do you understand by queue Discipline?
IN QUEueing theory,it is like how we serve people in waiting line --- 1.fcfs 2.round robin 3.sjf 4. siro 5.fifo
What are non preemptive scheduling algorithms?
Strictly speaking, nonpreemptive scheduling is when the scheduler does not stop the process from running in order to switch it with a different process, but instead, it lets the process to complete and then schedules a different process depending on the a scheduling algorithm is uses.
What is CPU sheduling algorithm?
Basically,this is a need in case of multiprogramming.For optimum utilization of CPU it should be utilised in the meanwhile time when some process is in waiting state for some I/O or waiting for some event to occur. So,for this many programs should be in memory in waiting state so that CPU can be allocated to some other process for optimum utilization of CPU. A schedule(time table in broad sense) which will decide Cpu will be allocated to which process when some previous process is in waiting state. Now this schedule is designed according to some criteria(algorithm) to decide CPU will be allocated to which process. Some Algorithms: 1.First Come First Serve(FCFS) 2.Shortest Job Scheduling(SJS) 3.RoundRobin Scheduling(RRS)
Comparison of FCFS SJF round robin algos?
FCFS = First Come First Serve SJF = Shortest Job First Round Robin = Skip from one job to the next giving each job an equal amount of processing time. (up to you or given) In an example: You have 4 jobs ahead of you. JobC, JobA, JobB, JobD and they were handed in to you, in that order. JobA will take 2 hours to do, JobB will take 1 hour, JobC will take 5 hours, and JobD will take 9 hours. FCFS, basically would mean you finish JobC first, since it came to you first. Then when JobC was done, you would work on JobA and so on. SJF, you would finish JobB first, then JobA, then JobC and then JobD. Round Robin, you would work on JobC for 1 hour, then JobA for 1 hour, then JobB for 1 hour and then JobD for 1 hour, and repeat.
What is the difference between pre emptive and non preemptive scheduling?
in pre emptive scheduling. a limited time period is fixed for every process in the CPU. no matter whether the process is completed or not ... the resource assinged to it will be taken back back abd will be given to the next process in the queue.while in non preemptive the resorces are with a process untill it finishes completely others wait for their turn till then. this kind of scheduling has a high probability of going into a deadlock.
