Operating System

Previous Year Questions
Gate CSGate CS 2022 | Question - 19 | Operating System

Consider the following threads, T1, T2, and T3 executing on a single processor, synchronized using three binary semaphore variables, S1, S2, and S3, operated upon using standard wait() and signal(). The threads can be context switched in any order and at any time. T1 T2 T3 while(true){ wait(S3); print("C"); signal(S2);} while(true){ wait(S1); print("B"); signal(S3);} while(true){ wait(S2); print("A"); signal(S1); } Which initialization of the semaphores would print the sequence BCABCABCA.?

Gate CSGate CS 2022 | Question - 26 | Operating System

Which of the following statements is/are TRUE with respect to deadlocks?

Gate CSGate CS 2022 | Question - 64 | Operating System

Consider a demand paging system with four-page frames (initially empty) and LRU page replacement policy. For the following page reference string 7, 2, 7, 3, 2, 5, 3, 4, 6, 7, 7, 1, 5, 6, 1 the page fault rate, defined as the ratio of number of page faults to the number of memory accesses (rounded off to one decimal place) is_________.

Gate CSGate CS 2020 | Question - 11 | Operating System

Consider allocation of memory to a new process. Assume that none of the existing holes in the memory will exactly fit the processs memory requirement. Hence, a new hole of smaller size will be created if allocation is made in any of the existing holes. Which one of the following statement is TRUE??

Gate CSGate CS 2020 | Question - 12 | Operating System

Consider the following statements about process state transitions for a system using preemptive scheduling. I. A running process can move to ready state. II. A ready process can move to running state. III. A blocked process can move to running state. IV. A blocked process can move to ready state. Which of the above statements are TRUE?

Gate CSGate CS 2020 | Question - 50 | Operating System

Consider the following set of processes, assumed to have arrived at time 0. Consider the CPU scheduling algorithms Shortest Job First (SJF) and Round Robin (RR). For RR, assume that the processes are scheduled in the order P1, P2, P3, P4. If the time quantum for RR is 4 ms, then the absolute value of the difference between the average turnaround times (in ms) of SJF and RR (round off to 2 decimal places is_______.

Gate CSGate CS 2020 | Question - 53 | Operating System

Consider a paging system that uses 1-level page table residing in main memory and a TLB for address translation. Each main memory access takes 100 ns and TLB lookup takes 20 ns. Each page transfer to/from the disk takes 5000 ns. Assume that the TLB hit ratio is 95%, page fault rate is 10%. Assume that for 20% of the total page faults, a dirty page has to be written back to disk before the required page is read from disk. TLB update time is negligible. The average memory access time in ns (round off to 1 decimal places) is ________.

Gate CSGate CS 2003 | Question - 81 | Operating System

Suppose we want to synchronize two concurrent processes P and Q using binary semaphores S and T. The code for the processes P and Q is shown below. Process P:while (1) { W: print '0'; print '0'; X:} Process Q:while (1) { Y: print '1'; print '1'; Z:} Synchronization statements can be inserted only at points W, X, Y and ZWhich of the following will ensure that the output string never contains a substring of the form 01n0 or10n1 where n is odd?