GATE CSE
Operating Systems
Process Concepts and Cpu Scheduling
Previous Years Questions

## Marks 1

Consider four processes P, Q, R and S scheduled on a CPU as per round robin algorithm with a time quantum of 4 units. The processes arrive in the orde...
Consider the following statements about process state transitions for a system using preemptive scheduling. I. A running process can move to ready sta...
The following C program is executed on a Unix/Linux system: #include < unistd.h > int main () { ...
Consider an arbitrary set of $$CPU$$-bound processes with unequal $$CPU$$ burst lengths submitted at the same time to a computer system. Which one of ...
The maximum number of processes that can be in $$Ready$$ state for a computer system with $$n$$ $$CPUs$$ is
Which one of the following is FALSE?
A scheduling algorithm assigns priority proportional to the waiting time of a process. Every process starts with priority zero (the lowest priority). ...
A process executes the code fork $$\left( {\,\,\,} \right);$$ fork $$\left( {\,\,\,} \right);$$ fork $$\left( {\,\,\,} \right);$$ The total number of...
A Computer handles several interrupt sources of which the following are relevant for this question: $$* \,\,\,$$ Interrupt from $$CPU$$ temperature s...
A thread is usually defined as a ''light weight process'' because an operating system $$(OS)$$ maintains smaller data structures for a thread than for...
Let the time taken to switch between user and kernel modes of execution be $${t_1}$$ while the time taken to switch between two processes be $${t_2}$$...
Which of the following statements are true? $${\rm I}.$$ Shortest remaining time first scheduling may cause starvation $${\rm II}.$$ Preemptive schedu...
A CPU generally handles an interrupt by executing an interrupt service routine
Group-1 contains some $$CPU$$ scheduling algorithms and Group-2 contains some applications. Match entries in Group-1 to entries in Group-2. Group-1 (P...
Consider the following statements about user level threads and kernel level threads. Which one of the following statements is FALSE?
Consider three $$CPU$$-intensive process, which require $$10,20$$ and $$30$$ time units and arrive at times $$0,2$$ and $$6$$ respectively. How many c...
Consider the following statements with respect to user-level threads and kernel-supported threads. i) Context switch is faster with kernel- supported...
Which of the following scheduling algorithms is non-preemptive?
A processor needs software interrupt to
Consider a set of $$n$$ tasks with known runtimes $${r_1},{r_2},.....\,{r_n}\,\,$$ to be run on a uniprocessor machine. Which of the following process...
A CPU has two modes-privileged and non-privileged. In order to change the mode from privileged to non-privileged
System calls are usually invoked by using:
Which of the following is an example of spooled device?
Consider $$n$$ processes sharing the $$CPU$$ in a round-robin fashion. Assuming that each process switch takes $$s$$ seconds, what must be the quantum...
The process state transition diagram in Figure is representative of ...
Which of the following is an example of spooled device?
Which scheduling policy is most suitable for a time-shared operating systems?

## Marks 2

Which of the following standard C library functions will always invoke a system call when executed from a single-threaded process in a UNIX/Linux oper...
Consider the following set of processes, assumed to have arrived at time 0. Consider the CPU scheduling algorithms Shortest Job First (SJF) and Round ...
Consider the following four processes with arrival times (in milliseconds) and their length of CPU bursts (in milliseconds) as shown below : These pr...
Consider the following processes, with the arrival time and the length of the CPU burst given in milliseconds. The scheduling algorithm used is preemp...
For the processes listed in the following table, which of the following scheduling schemes will give the lowest average turnaround time? .tg {borde...
Consider a uniprocessor system executing three tasks T1, T2 and T3, each of which is composed of an infinite sequence of jobs (or instances) which arr...
Three processes $$A, B$$ and $$C$$ each execute a loop of $$100$$ iterations. In each iteration of the loop, a process performs a single computation t...
An operating system uses $$shortest$$ $$remaining$$ $$time$$ $$first$$ scheduling algorithm for pre-emptive scheduling of processes. Consider the foll...
Consider the following set of processes that need to be scheduled on a single $$CPU.$$ All the times are given in milliseconds. .tg {border-collap...
Consider the $$3$$ processes, $$P1,$$ $$P2$$ and $$P3$$ shown in the table. .tg {border-collapse:collapse;border-spacing:0;} .tg td{font-family:Ari...
Consider the following table of arrival time and burst time for three processes $$P0,P1$$ and $$P2$$. .tg {border-collapse:collapse;border-spacing:0...
In the following process state transition diagram for a uniprocessor system, assume that there are always some processes in the ready state: Now cons...
A process executes the following code for (i = 0; i < n; i + +) fork ( ); The total number of child processes created is...
Which of the following is/are true of the auto-increment addressing mode? $${\rm I}.\,\,\,$$ It is useful in creating self-relocating code $${\rm II}.... An operating system uses Shortest Remaining Time first$$(SRT)$$process scheduling algorithm. Consider the arrival times and execution times for the ... Consider three processes (process id$$0,1,2,$$respectively) with compute time bursts$$2, 4,$$and$$8$$time units. All processes arrive at time ze... Consider three processes, all arriving at time zero, with total execution time of$$10,20,$$and$$30$$units, respectively. Each process spends the f... Consider the following code fragment: if (fork() == 0) { a = a + 5; printf("%d, %d \n", a, &a); } else { a = a - 5; printf ("%d, %d \... Consider the following set of processes, with the arrival times and the$$CPU$$-burst times given in milliseconds. What is the average turnaround t... A uni-processor computer system only has two processes, both of which alternate$$10msCPU$$bursts with$$90ms{\rm I}/O$$bursts. ... Draw the process state transition diagram of an$$OS$$in which (i) each process is in one of the five states: created, ready, running, blocked (i.e.... Which combination of the following features will suffice to characterize an$$OS$$as a multi-programmed$$OS?(a).$$More than one program may be... Which of the following does not interrupt a running process? A multi-user, multi-processing operating system cannot be implemented on hardware that does not support: Which of the following actions is/are typically not performed by the operating system when switching context from process$$A$$to process$$B$$? Four jobs are waiting to be run. Their expected run times are$$6, 3, 5$$and$$x$$.$${\rm I}$$n what order should they be run to minimize the averag... Four jobs to be executed on a single processor system arrive at time$${0^ + }$$in the order$$A, B, C, D.$$their burst$$CPU$$time requirements a... The sequence$$.........$$is an optimal non-preemptive scheduling sequence for the following jobs which leaves the$$CPU$$idle for$$..........$$Un... The details of an interrupt cycle are shown in Figure Given that an interrupt input arrives every$$1msec,$$what is the percentage of the tota... Assume that the following jobs are to be executed on a single processor system. .tg {border-collapse:collapse;border-spacing:0;} .tg td{font-family... Which of the following is an example of a spooled device? The highest-response ratio next scheduling policy favours$$.......$$jobs, but it also limits the waiting time of$$ ..... jobs.
State an undesirable characteristic of each of the following criteria for measuring performance of an operating system: (a) Turn around time. (b) ...
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