اسئلة مراجعة نهائية لمادة نظم التشغيل

[رينادي]

السلام عليكم
مساكم الله بالخير
جيتكم و انا متفائلة بمساعدتكم
عندي اسئلة مراجعة نهائية لمادة نظم التشغيل os
و ما عرفت احلها و لا لقيت لها حلول بالانترنت
الله يسعدكم اللي يعرف يحل لا يبخل علي و له دعوة بظهر الغيب
اختباري النهائي بكرا و الاسئلة جدا مهمة

Name two advantages of using binary semaphores to achieve mutual exclusion among several processes over Peterson's solution

Explain the advantages of dynamically re-allocated process priorities. HINT: think about the performance of I/O-bound processes

There are five jobs with arrival times 0, 0, 2, 2 and 4 minutes and execution times 2, 2, 1, 2 and 2 minutes, respectively. What is the average turnaround time using round-robin scheduling with a time quantum equal to 1 minute? What is the average waiting time using the same scheduler?

Consider five jobs A through E with execution times 2, 4, 1, 1, 1 seconds, respectively. Their arrival times are 0, 0, 3, 3, 3 seconds. Draw the Gantt Chart for the CPU using the shortest-job-first scheduling algorithm. What is the average turnaround time? Is this the optimal turnaround time among the nonpreemtive scheduling algorithms?

Suppose that the above jobs have the following sizes: 100KB, 400KB, 400KB, 200KB, 200KB. Suppose that the computer has a RAM capacity of 800KB allocated through the contiguous allocation method. Draw the memory usage during the execution of the jobs using shortest-job-first scheduling. (Assume that the time to load a process from the backing store is negligeable.) Calculate the resulting external fragmentation each time. Calculate the average turnaround time. (Notice the effects of the memory allocation mechanism on the performance) ?

A system has three processes P1, P2 and P3 and three types of dedicated resources R1 with three instances, R2 with two instances, and R3 with one instance. Suppose the current system's state is as follows:

 P1 holds one unit of R1 and request one unit of R2;

 P2 holds two units of R2 and requests two units of R1 and one unit of R3;

 P3 holds one unit of R3 and requests one unit of R1.

Is there a deadlock in the system? Explain your answer.

Discuss the three ways to implement process page tables (name the ways and state their advantages and disadvantages)

For each of the following factors, explain whether it is in favor of a large page size or a small page size:

- Internal fragmentation

- Process table size

- I/O overhead

- Locality of reference

For example, if we want to keep the process table size small, we'd better have a large page size (and vice versa): By increasing the page size, a process will have fewer pages; since each page must have one entry in the page table, therefore the number of entries in the page table (= its size) will be smaller

A small computer has a RAM with 4 frames. A process makes the following list of page references: 1, 2, 3, 4, 1,

5, 2, 3, 1, 2. How many page faults occur using FIFO and Least-Recently-Used page replacement algorithms

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