Table of Contents
What are the advantages and disadvantages of first come first serve?
1. First Come First Serve (FCFS):
- Advantages – It is simple and easy to understand.
- Disadvantages – The process with less execution time suffer i.e. waiting time is often quite long. Favors CPU Bound process then I/O bound process.
What are the advantages of first come first served?
Advantages of the First Come First Serve Scheduling It is the simplest and easy to implement algorithm programmatically. The FCFS algorithm is implemented using a FIFO Queue in the data structure. Just like in FIFO, the new data element enters from the tail of the queue and exit from the head of the queue.
What is the disadvantage of first come first served?
Disadvantages: This scheduling method is nonpreemptive, that is, the process will run until it finishes. Because of this nonpreemptive scheduling, short processes which are at the back of the queue have to wait for the long process at the front to finish. Throughput is not efficient.
What are the disadvantages of SJF scheduling algorithm?
Here are some drawbacks/cons of SJF algorithm:
- Job completion time must be known earlier, but it is hard to predict.
- It is often used in a batch system for long term scheduling.
- SJF can’t be implemented for CPU scheduling for the short term.
- This algorithm may cause very long turnaround times or starvation.
What Is First In First Out Scheduling?
First in, first out (FIFO), also known as first come, first served (FCFS), is the simplest scheduling algorithm. FIFO simply queues processes in the order that they arrive in the ready queue.
Which is better SJF or SRTF?
Processes having same arrival time will convert SRTF to SJF….Differences:
|Shortest Job First:||Shortest Remaining Job First:|
|It is a non-preemptive algorithm.||It is a preemptive algorithm.|
|It leads to comparatively lower throughput.||It leads to increased throughput as execution time is less.|
What is the average turn around time with SRT?
In SRT, a running process may be preempted by new process with shorter estimated run time….Consider the following 4 jobs.
|Job||Turn Around Time|
|1||16-0 = 16|
|2||5-1 = 4|
|3||25-3 = 22|
|4||10-4 = 6|
How is turn around time calculated SJF?
Turnaround Time = Total Turnaround Time- Arrival Time P1 = 28 – 0 =28 ms, P2 = 5 – 1 = 4, P3 = 13 – 2 = 11, P4 = 20 – 3 = 17, P5 = 8 – 4 = 4 Total Turnaround Time= 64 mills.
Is SRTF fair?
SJF/SRTF: Not fair, but average waiting time is minimized assuming we can accurately predict the length of the next CPU burst. Starvation is possible; Lottery Scheduling: Fairer with low average waiting time, but less predictable.
Which scheduling CPU picks the job with shortest job?
Shortest Job First(SJF) Scheduling
- This is the best approach to minimize waiting time.
- This is used in Batch Systems.
- It is of two types:
- To successfully implement it, the burst time/duration time of the processes should be known to the processor in advance, which is practically not feasible all the time.
What is difference between preemptive and Nonpreemptive scheduling?
In preemptive scheduling the CPU is allocated to the processes for the limited time whereas in Non-preemptive scheduling, the CPU is allocated to the process till it terminates or switches to waiting state.
What are the 5 basic states of a process?
- New. A program which is going to be picked up by the OS into the main memory is called a new process.
- Ready. Whenever a process is created, it directly enters in the ready state, in which, it waits for the CPU to be assigned.
- Block or wait.
- Completion or termination.
- Suspend ready.
- Suspend wait.
What is the difference between starvation & Aging?
To avoid starvation, we use the concept of Aging. In Aging, after some fixed amount of time quantum, we increase the priority of the low priority processes. By doing so, as time passes, the lower priority process becomes a higher priority process. The only thing that we are taking care of is starvation.
How deadlock is detected?
The main task of the OS is detecting the deadlocks. The OS can detect the deadlocks with the help of Resource allocation graph. In single instanced resource types, if a cycle is being formed in the system then there will definitely be a deadlock.
How do you recover from a deadlock?
For this, we use two methods:
- (a). Abort all the Deadlocked Processes: Aborting all the processes will certainly break the deadlock, but with a great expenses.
- (b). Abort one process at a time untill deadlock is eliminated: Abort one deadlocked process at a time, untill deadlock cycle is eliminated from the system.
What is the simplest deadlock recovery method?
• Recovery through killing processes. – Crudest but simplest way to break a deadlock. – Kill one of the processes in the deadlock cycle: the other processes. get its resources. – Choose process that can be rerun from the beginning.
Why deadlock recovery is needed?
Deadlock recovery performs when a deadlock is detected. When deadlock detected, then our system stops working, and after the recovery of the deadlock, our system start working again. Therefore, after the detection of deadlock, a method/way must require to recover that deadlock to run the system again.
How deadlock is detected in Java?
There is one more method to detect Deadlock in Java, it can be done by running the program in CMD. All we need to do is collect thread dumps and then we have to command to collect, depending upon the operating system. If we are running Java 8 on windows, a command would be jcmd $PID Thread. print.
What is deadlock ignorance?
Deadlock Ignorance is the most widely used approach among all the mechanism. This is being used by many operating systems mainly for end user uses. In this approach, the Operating system assumes that deadlock never occurs. In these types of systems, the user has to simply restart the computer in the case of deadlock.