Questions tagged [operating-systems]

Questions about the principles of software that interfaces between hardware and applications.

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124 views

How can i draw a general resource graph which cannot be completely reduced but which is free from deadlock?

How can i draw a general resource graph which cannot be completely reduced but which is free from deadlock? A general resource graph which can be completely reduced and hence is free from deadlock is ...
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12 views

What is a batch based interface?

I came across this description of Batch Interface: "commands and directives are used to manage those commands that are entered into files and those files get executed. " I would really appreciate if ...
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1answer
35 views

What is a 'dynamic entity' in computer science?

I am doing some reading into computer science and how the computing system works in order to be ready for my 1st year at university doing a Computer Science degree. I came across a term within the ...
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1answer
6k views

How to compute total internal and external fragmentation

I want to find the total external and internal fragmentation. What I understand is that external fragmentation occurs when processes are loaded and removed from memory, causing memory to be broken ...
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980 views

Segmentation and paging

I am given a system with a segmented paging architecture. Both physical and virtual address spaces contain $2^{16}$ bytes each. The virtual address space is divided in $8$ equal size segments. The ...
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2k views

Operating Systems - SJN/Round Robin - turn around time + waiting time

2.(10 pts) a) You are given 4 processes in a batch system that all arrive at time 0 with the following CPU burst times: P1 : 35, P2: 25, P3: 13, P4: 22. Assuming there is no context switch ...
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1answer
14 views

How many segments a process can have in operating system employing Segmentation for memory management

Some facts about "Segmented Paging" 1) Each process has one segment table. 2) There is one-page table per segment. Fact about "Paged segmentation" 3) Contains page table of segment table. Now ...
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13 views

Can many threads run in a parallel in many-to-one model?

The book I am reading suggests that in a many-to-one multi-threading model, the threads are unable to run in parallel in a multi-core system. I am thinking this is not the case because if we have many-...
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I couldn't find chapter 1 of JMU open source textbook of cs361 course on computer systems fundamentals [closed]

Please help me find this , I need to find this chapter 1 , this is the link https://w3.cs.jmu.edu/kirkpams/OpenCSF/Books/cs361/html/index.html
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1answer
18 views

Calculation of speed up of a program executed in multi-threaded system

Speed up of execution of a program is to be calculated within a multi-threading rather than a single thread system. The program's 30% instruction can be executed serially & rest can be executed ...
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1answer
46 views

EDF vs Rate Monotonic context changes

I'm studying real time scheduling algorithms. In particular EDF and Rate monotonic. I have an intuition that using EDF we have less context changes than using Rate Monotonic. But i dont know how to ...
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1answer
2k views

What is the difference between caching, buffering and paging? Expecting a detailed answer on the OS level

I have been reading about caching and buffering it seems about the same to me can't get hold of the differences clearly and paging, for now the only difference I understand between paging and caching ...
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1answer
38 views

How are logical addresses of instruction operands mapped to physical addresses?

Is address translation for all operands in single instruction done only once and then are all operands fetched continuously? For example, consider any dummy instruction ...
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17 views

Which page replacement algorithm causes thrashing

This is rather simple conceptual question. I can guess the answer, but no text explicitly discuss thrashing in the context of different page replacement algorithm. So I want to take your confirmation ...
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39 views

What are necessity and sufficiency?

I was reading deadlock topic from Operating Systems book by Stallings. It states four pre requisites for deadlock: Mutual exclusion No preemption Hold and wait Circular wait It then have following ...
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33 views

How can I solve this deadlock related problem mathematically?

I came across following problem: A system has n resources R0,…,Rn-1,and k processes P0,….Pk-1.The implementation of the resource request logic of each process Pi is as follows: ...
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17 views

Comparing wait-signal alternatives for synchronizing two piece of programs

I came across following problem: A certain computation generates two arrays a and b such that ...
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1answer
45 views

Designing solution to critical section problem with two semaphores vs single semaphore

I came across following problem: Let two processes P1 and P2 are there: ...
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1answer
805 views

How do stack-based cache algorithms avoid Belady's anomaly?

I was going through page replacement algorithms from Galvin's Operating System book. I encountered this line about LRU: A stack algorithm is one in which the pages kept in memory for a frame set ...
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0answers
19 views

Does this state certify to be called as a deadlock?

I came across following problem: Barrier is a synchronization construct where a set of processes synchronizes globally i.e., each process in the set arrives at the barrier and waits for all others ...
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1answer
81 views

How does dynamic memory-allocation exactly work?

I have wondered about ordinary code. Assume we are running this code on any modern System like Unix/Linux/Mac/Windows. This code is C, but it should work with every language which is close to the ...
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1answer
454 views

How to calculate average waiting time for round robin cpu scheduling?

I have tried to calculate average waiting time for the below details there are two answers I'm getting using two methods I'm not understanding which one is correct? The time quantum is 2 This is the ...
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1answer
65 views

Why is 2^32 in a 32-bit system = 4GiB and not 4Gib?

I was watching this video 32-Bit vs 64-Bit - The Advantage and at 1:19 (timestamp) the narrator mentioned the 4GB memory allocation for the 32-bit system. I later found out it should've been 4GiB but ...
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16 views

Why we need size of the page table should be some fraction of virtual address space

The Page Table should have all virtual page number which are in its logical address space, Why it's the case? Is it because we want to access Page Table entry fast just like an array where key is ...
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1answer
29 views

Why does paging not have external fragmentation?

I have read that paging does not suffer from external fragmentation as the frames and the pages are all of the equal sizes, but when we store a last level page table in a frame at that time it may not ...
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4answers
7k views

Why do we need the valid-invalid bit in a page table?

I'm reading about memory management in Operating System Concepts, by A. Silberschatz. The author says: [...] the user process by definition is unable to access memory it does not own. It has no ...
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2answers
2k views

Scheduling algorithms and quantum time

I would like to know what impacts does a scheduling algorithm say Round Robin of FIFO have on a Operating system. I understand the a scheduling algorithm has the processes run in burst then switch ...
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23 views

Why in the Map Reduce Implementation, why not stream the records to the reducer (via TCP) as they are being produced by the mappers?

In the Map-Reduce implementation, the reducers start when all mappers finish their jobs. Why don't we stream the records from mappers to reducers while they are being processed instead? I think there ...
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1answer
447 views

Convoy effect in priority scheduling and SJF (Non preemptive)

In books, I have read that FCFS suffers from convoy effect. I think that even SJF and priority(both preemptive and non preemptive) can suffer from convoy effect. In SJF, if a process with large burst ...
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1answer
80 views

Task scheduling algorithm that limits concurrency

My prof introduced us an algorithm with semaphores that was used to solve the "dining philosophers" problem. The algo is ok, apart from that it limits concurrency. What does mean that it "limits ...
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2answers
65 views

What type of operations are seen the most at the physical disk level — reads or writes? Why?

This question came up in my operating systems class in a section about file system cache and RAID. I'm speculating that the answer is that writes are seen more at the physical disk level because an ...
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6answers
2k views

How can a CPU access more memory locations than 2^wordsize?

I noticed that CPU's like the 8086 and especially the 8080 have the ability to access more memory than what one would normally assume. The 8080, for example, has an 8-bit word size but can use a 16-...
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28 views

Any good source explaining multiprocessor synchronization techniques and their implementation

I need to study how synchronization is done in a multiprocessor operating system, but I am unable to find a good source. I have read about it in the book "Modern Operating System" by Tanenbaum, but I ...
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2answers
103 views

Why operating system needs interrupt stack, if it has process control block?

I'm reading about an operating system but some concept confuses me. What doesn't confuse me: When an interrupt or system call or processor exception occurs, it happens when user mode tries to ...
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16 views

Inputting values to register files

I'm trying to understand how to register files. The question below is from past exam paper: The following diagram shows the register-file from a simple 8-bit machine I don't fully get register ...
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1answer
25 views

What architectural features will allow this microprocessor to access a separate “I/O space”?

I'm studying for my final and don't understand this question. Here is the full question (from Stallings 8th edition): Consider a hypothetical microprocessor generating a 16-bit address (e.g., ...
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1answer
46 views

How exactly does a CPU do process scheduling?

I know in theory how various scheduling algorithms work, such as round robin, where each process is given small time slices to run a few instructions, before the operating system passes execution onto ...
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33 views

How can an unstable kernel write a memory dump?

I always wondered how a kernel that became unstable, e.g. due to a BSOD or a kernel panic, is able to do specific tasks. For example, if a Windows driver corrupts the stack of the kernel. It leads to ...
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1answer
146 views

Why do OS and DBMS have their own synchronisation mechanisms, when OS can alone do it and it sits at the bottom of DB?

I know that synchronization is important in the OS, but why do we need a separate topic synchronization and concurrency in the DBMS? The OS concentrates on program synchronization while the DBMS ...
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1answer
112 views

Single processor system supporting two running processes, A and B, with the following sequential execution patterns [closed]

Can anyone please help me with the following question? Consider a single processor system supporting two running processes, A and B, with the following sequential execution patterns: A: [CPU 8 ms; ...
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464 views

Latency and Throughput Bounds

Say that I have a superscalar processor and I am given the latency, issue and capacity (in clock cycles) for different instructions. What is the general formula for latency bound and throughput bound?...
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22 views

Understanding Bounded Waiting

I am trying to understand bounded waiting and i have a question. The definition is as follows: Bounded waiting - There exists a bound, or limit, on the number of times that other processes are ...
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1answer
33 views

what is the difference between Operating system and Window Systems?

Quoting from Tannenbaum_Operating_Systems_Design : On top of the operating system is the rest of the system software. Here we find the command interpreter (shell), window systems, compilers, ...
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765 views

Deadlock and safe state

I read that system being in safe state doesn't guarantee that deadlock is not possible. Can someone give me an example where system is in safe state and deadlock is possible?
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1answer
56 views

How does operating system display decimal numbers which are stored as binary? [duplicate]

What kind of magic happen with bytes in memory?
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Memory Mapping Segment

I read that "Memory Mapping Segment"/"memory mapped file" is a segment of the virtual memory of a process, where a file or file-like Ressource is loaded into. It is for high performance file I/O. I ...
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1answer
31 views

How the operating system allocated to dual-channels memory?

I learned that the boot loader transmit the operating system from Hard Disk to Main Memory during the booting process. I wonder, today's computers are equipped with multiple slice of memory of dual-...
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1answer
6k views

How does the OS determine the CPU burst time of a process?

This question is related to OS. After having solved many problems in CPU scheduling I was wondering how does the CPU know the burst time of all the processes in the main memory before executing them? ...
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4answers
2k views

Operating System - CPU scheduling Decisions

I understand that CPU scheduling takes place on 4 circumstances listed below: When the process changes state from Running to Ready Changes state from Running to Waiting Changes state from Waiting to ...