अपरेटिङ सिस्टम – Operating System MCQ
अपरेटिङ सिस्टम – कम्प्युटर र IT
Operating System · Computer & IT (Technical) · ४०४ प्रश्न
४०४ प्रश्न उपलब्ध। मोड छान्नुहोस्:
अपरेटिङ सिस्टम: प्रश्न र उत्तर
सही लागेको विकल्पमा थिच्नुहोस्। सही भए हरियो, गलत भए रातो देखिन्छ; ३ सेकेन्डपछि सही उत्तर र व्याख्या देखिन्छ।
सही: ० / ०
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A counting semaphore S is initialised to 5. Then 7 wait (P) operations and 3 signal (V) operations are performed on it. What is its final value?
सही उत्तर: ख) 1
Each wait decreases S by 1 and each signal increases it by 1: 5 - 7 + 3 = 1.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A semaphore whose value can range over an unrestricted domain, used to control access to a resource with several instances, is a:
सही उत्तर: ख) Counting semaphore
A counting semaphore is initialised to the number of available instances and allows that many processes to use the resource at once.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Choosing a very small time quantum in Round Robin scheduling mainly causes:
सही उत्तर: क) High context-switching overhead
A tiny quantum forces very frequent context switches, so a large share of CPU time is wasted on switching instead of useful work.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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If the time quantum in Round Robin scheduling is larger than every CPU burst, Round Robin behaves like:
सही उत्तर: क) FCFS
With a very large quantum, each process finishes its burst before the quantum expires, so processes simply run in arrival order as in FCFS.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Multilevel feedback queue scheduling differs from simple multilevel queue scheduling because it:
सही उत्तर: घ) Allows processes to move between queues based on their CPU usage
In a multilevel feedback queue, a process that uses too much CPU is moved to a lower-priority queue and a long-waiting one can be moved up.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Five processes P1 to P5 arrive at time 0 with burst times 10, 1, 2, 1 and 5 ms and priorities 3, 1, 4, 5 and 2 (smaller number = higher priority). Under non-preemptive priority scheduling, the average waiting time is:
सही उत्तर: ग) 8.2 ms
The order is P2, P5, P1, P3, P4 with waiting times 0, 1, 6, 16 and 18 ms; 41 / 5 = 8.2 ms.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Processes P1, P2, P3 and P4 arrive at 0, 1, 2 and 3 ms with burst times 8, 4, 9 and 5 ms. Under SRTF (preemptive SJF) scheduling, the average waiting time is:
सही उत्तर: ख) 6.5 ms
Waiting times are P1 = 9, P2 = 0, P3 = 15 and P4 = 2 ms; the total 26 divided by 4 gives 6.5 ms.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Modern Windows and Linux map each user-level thread to its own kernel thread. This multithreading model is the:
सही उत्तर: घ) One-to-one model
In the one-to-one model every user thread has a kernel thread, giving true parallelism on multiple cores at the cost of more kernel threads.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Compared with creating a new process, creating a new thread within an existing process is:
सही उत्तर: ग) Faster, because threads share the process's code, data and open files
Threads of the same process share its address space and resources, so creating and switching threads is cheaper than for processes.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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User-level threads managed by a thread library, without the kernel knowing about them, have the disadvantage that:
सही उत्तर: ख) A blocking system call by one thread blocks the entire process
Since the kernel sees only one schedulable entity, if one user-level thread blocks in a system call, the whole process blocks.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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