GATE CS Operating System questions

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 following process scheduling algorithms would minimize the average waiting time in the ready queue?

Consider the following processes, with the arrival time and the length of the CPU burst given in milliseconds. The scheduling algorithm used is preemptive shortest remaining-time first. …

Consider the following two-process synchronization solution. …

Consider a non-negative counting semaphore $S$. The operation $P(S)$ decrements $S$, and $V(S)$ increments $S$. During an execution, $20$ $P(S)$ operations and $12$ $V(S)$ operations are issued in some order. The largest initial value of $S$ for which at least one $P(S)$ operation will remain blocked is _______

In which one of the following page replacement algorithms it is possible for the page fault rate to increase even when the number of allocated frames increases?

Consider a disk pack with a seek time of $4$ milliseconds and rotational speed of $10000$ rotations per minute (RPM). It has $600$ sectors per track and each sector can store $512$ bytes of data. Consider a file stored in the disk. The file contains $2000$ sectors. Assume that every sector access necessitates a seek, and the average rotational …

Consider a main memory with five-page frames and the following sequence of page references: $\text{3, 8, 2, 3, 9, 1, 6, 3, 8, 9, 3, 6, 2, 1, 3}$. Which one of the following is true with respect to page replacement policies First In First Out (FIFO) and Least Recently Used (LRU)?

Consider a uniprocessor system executing three tasks $T_{1}, T_{2}$ and $T_{3}$ each of which is composed of an infinite sequence of jobs (or instances) which arrive periodically at intervals of $3, 7$ and $20$ milliseconds, respectively. The priority of each task is the inverse of its period, and the available tasks are scheduled in order of …

Suppose the following disk request sequence (track numbers) for a disk with $100$ tracks is given: $45, 20, 90, 10, 50, 60, 80, 25, 70.$ Assume that the initial position of the R/W head is on track $50$. The additional distance that will be traversed by the R/W head when the Shortest Seek Time First (SSTF) algorithm is used compared to the SCAN …

Consider a system with byte-addressable memory, $32\text{-bit}$ logical addresses, $4\;\text{kilobyte}$ page size and page table entries of $4\;\text{bytes}$ each. The size of the page table in the system in $\text{megabytes}$ is___________.

The following two functions $P1$ and $P2$ that share a variable $B$ with an initial value of $2$ execute concurrently. $$\begin{array}{|l|l|}\hline \text{P1() \{ } & \text{P2()\{} \\ \text{ C = B - 1;} & \text{ D = 2 * B; } \\ \text{ B = 2 * C;} & \text{ B = D - 1;} \\ \text{\}} & \text{\}} \\ \hline \end{array}$$ The number of …

Consider a typical disk that rotates at $15000$ rotations per minute (RPM) and has a transfer rate of $50 \times 10^6$ bytes/sec. If the average seek time of the disk is twice the average rotational delay and the controller's transfer time is $10$ times the disk transfer time, the average time (in milliseconds) to read or write a $512$-byte sector of …

A computer system implements $8\;\text{kilobyte}$ pages and a $32\text{-bit}$ physical address space. Each page table entry contains a valid bit, a dirty bit, three permission bits, and the translation. If the maximum size of the page table of a process is $24\;\text{megabytes}$, the length of the virtual address supported by the system is _______ …

Consider $6$ memory partitions of sizes $200$ $\text{KB}$, $400$ $\text{KB}$, $600$ $\text{KB}$, $500$ $\text{KB}$, $300$ $\text{KB}$ and $250$ $\text{KB}$, where $\text{KB}$refers to $\text{kilobyte}$. These partitions need to be allotted to four processes of sizes $357$ $\text{KB}$, $210$ $\text{KB}$, $468$ …

A computer system implements a $40\;\text{-bit}$ virtual address, page size of $8\;\text{kilobytes}$, and a $128\text{-entry}$ translation look-aside buffer $\text{(TLB)}$ organized into $32$ sets each having $4$ ways. Assume that the $\text{TLB}$ tag does not store any process id. The minimum length of the $\text{TLB}$ tag in bits is ______.

A system has $6$ identical resources and $N$ processes competing for them. Each process can request at most $2$ resources. Which one of the following values of $N$ could lead to a deadlock?

Consider the following policies for preventing deadlock in a system with mutually exclusive resources. Process should acquire all their resources at the beginning of execution. If any resource is not available, all resources acquired so far are released. The resources are numbered uniquely, and processes are allowed to request for resources only in …

For the processes listed in the following table, which of the following scheduling schemes will give the lowest average turnaround time? …

Two processes $X$ and $Y$ need to access a critical section. Consider the following synchronization construct used by both the processes …

The maximum number of processes that can be in $\textit{Ready}$ state for a computer system with $n$ CPUs is :