Questions tagged [operating-systems]
Questions about the principles of software that interfaces between hardware and applications.
643
questions
3
votes
1answer
30 views
CPU scheduling Decisions
Operating System - CPU scheduling Decisions
The question above talks about why CPU scheduling does not take place when ready to running.
But I wonder why CPU scheduling does not take place when new ...
-1
votes
1answer
26 views
Page Size, Physical Memory Size, max Program Size
In a 64 bit computer, the logical address space is 64MB and physical memory size is
2GB. Paging is implemented with 4KB pages. Determine the logical and physical
address components. (That is, how many ...
0
votes
0answers
27 views
Renaming of linear list directory
Consider a linear list-based directory implementation in a file system. Each directory is a list of nodes, where each node contains the file name along with the file metadata, such as the list of ...
0
votes
0answers
14 views
What would happen in this priority-based round-robin CPU scheduling algorithm case?
I've been implementing some kind of CPU Scheduling Algorithms in Python. And I am really confused with one of the cases what'd be implemented in this case.
Let us assume that the time quantum is 10.
...
1
vote
1answer
19 views
If we execute kernel programs in the user mode and user programs in kernel mode what are some consequences
Question on operating system
If we execute kernel programs in the user mode and user programs in kernel mode what are some consequences
-5
votes
0answers
17 views
How to remove this icon from appearing while browsing? [closed]
I have added a screenshot of the icon that appears while I move the mouse during browsing in Microsoft edge. If anybody knows how to fix this problem please help me. Thanks in advance.
3
votes
0answers
31 views
Is there a “theory” of operating systems?
Is there a theory for Operating Systems?
That is, subfields of CS have theoretical parts; i.e. PL has type theory, ML has mathematical theorems, security has a lot of provable properties, etc.
There ...
1
vote
2answers
46 views
Memory addressing rapidity
I've got a few questions related to the different types of memory that we can find:
To my understanding, since there are registers that are close physically to the CPU, these are much faster to access,...
0
votes
2answers
63 views
Best operating system for a computing degree? [closed]
Not sure which OS is best to invest in for my computer science degree. Have had varying opinions - from your experience in education or working in the sector, what is the operating system that will ...
1
vote
0answers
8 views
How to use Parallel Semaphores for Dining Philosophers Problem
I am in an intro to OS class and we are learning about mutual exclusion and semaphores. One classical problem we learned about was the dining philosophers problem. My professor touched on the ...
2
votes
2answers
121 views
How are kernels (and operating systems in general) written in C?
I'm trying to understand how you set about writing an OS in something like C.
I've always used C to write applications - using commands like malloc and ...
1
vote
0answers
44 views
Starvation and Livelock
I think Option C is false. Following is my thought process:
Starvation in general mean Process is waiting indefinitely for the resource or to get scheduled etc. [A/c to Galvin Book]. So, here in this ...
2
votes
6answers
648 views
Representation of unsigned integer on a little endian, big endian computer
This is a GATE 2021 exam question.
If the numerical value of a 2-byte unsigned integer on a little endian computer is 255 more than that on a big endian computer, which of the following choices ...
0
votes
0answers
35 views
Is it okay to understand Job Queue Like this?
I have a hard time understanding the concept of job queue.
Is it right if I understand job queue like the following???
For example, when user click the icon of an exe file, the newly created process ...
1
vote
1answer
33 views
Question about pointer in PCB structure and meaning of job queue
PCB structure exists inside kernel area. And in ready queue, which is Linked List, each Node of the queue is PCB.
And this mean PCB Node has the next address of PCB in the queue, right?? Then My ...
0
votes
0answers
18 views
Page fault rate while calculating effective access time
So here is a question regarding calculating effective access time (EAT).
So the question is :
suppose a system with an average page page-fault service time of 6 milliseconds and
a memory access time ...
0
votes
0answers
23 views
Different ways to avoid deadlocks
I am thinking of techniques that we can implement in order to avoid deadlocks in processes. While I am aware of some tactics, e.g. killing a process when we reach a deadlock, or using spooling, would ...
1
vote
1answer
37 views
How are semaphores and test-and-set instructions connected?
Cheers, so my textbook explains these parts very poorly, so I would gladly take any advice! I am confused between the test-and-set instructions, which per my book is a very common CPU instruction set, ...
0
votes
0answers
13 views
Minimal number of resources such that the system is considered safe?
In a system with a single type of resource, there are 8 processes with the following maximal requirements:
Process
P1
P2
P3
P4
P5
P6
P7
P8
MAX
75
60
65
35
30
45
30
30
Specify the minimal value for ...
0
votes
0answers
31 views
How many different values can a shared variable take in concurrent computing?
Question:
Is there a way to find out number of different values that a shared variable can take in concurrent computing, in general, without listing all the possibilities and then counting the ones ...
1
vote
0answers
9 views
Regular OS Vs RTOS
I am curious to know if RTOS provides deterministic scheduling gurantees then why not all OS'es are RTOS?
In what sense regular OS say linux better then RTOS say FreeRTOS?
0
votes
1answer
47 views
OS: Are User-level threads and software threads (and also kernel-level threads and hardware threads) the same?
I am referencing the Book Fundamentals of Computer Algorithms" by Ellis Horowitz et al.
At the part which they talk about multi-threading models, user-level and kernel-level thread are introduced....
3
votes
0answers
39 views
Why do we need hashed page tables for Paging in Operating Systems?
I understand that we might need hierarchical paging to handle page tables with sizes greater than the size of one frame, but what is the use of Hashed Page tables then? I would understand if we were ...
0
votes
0answers
20 views
Is logical to physical address conversion inclusive?
If I am trying to translate a logical address of page N and offset O, and my translation unit tells me the translation has a base address of B and a length of L, is the length L inclusive or will it ...
0
votes
2answers
26 views
Does the host operating system know the content of your messages in a messaging applications?
Let's say you are using a messaging application (Microsoft Team, Skype, Telegram,..) on an operating system (Windows, MacOS, Linux). Does the OS know what you are sending or receiving? If yes, how? ...
1
vote
1answer
380 views
Algorithm favours CPU bound or I/O bound processes
Some scheduling algorithms favour CPU bound processes while others favour I/O bound processes.
Which algorithm favours which type of process?
My answers:
SJF favours I/O bound processes.Explanation: ...
-2
votes
1answer
37 views
• How CPU identify that which device is sending the request? • How CPU decide which action should be taken for each request?
• How CPU identifies which device is sending the request?
• How CPU decide which action should be taken for each request?
0
votes
0answers
24 views
Deadlock still occurs
Is it in in a deadlocked state?
In this graph, there is a deadlock initially I think. Since P1 is holding R1 and waiting for R2; P2 is holding R2 and waiting for R1 and R3; P3 is holding R3 and ...
0
votes
0answers
11 views
How to enforce synchronization with two semaphores
Assume I have 4 threads, A B C D respectively.
A finishes before B starts.
B finishes before C or D start.
How should I initial values and synchronize threads with 2 semaphores?
0
votes
0answers
26 views
Exception handling
In problem 1 part D) of https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-004-computation-structures-spring-2017/c17/c17s3/os_answers.pdf, how come process 1 is never scheduled?...
0
votes
1answer
92 views
Flow of control when calling a function
I am learning about embedded and operating systems. I would like to know the order of control flow that occurs when a user-space C application calls a function, for example, printf().
I am slightly ...
1
vote
1answer
58 views
Why does an inverted page table keep a chain of pages per frame when it can only store one of such pages?
I'm currently dealing with inverted page tables and how they work. If I understood correctly, an IPT is a table that maps a frame number to a PID and page number. The way this works is by having a ...
0
votes
0answers
27 views
Simultaneous buffer access in the bounded buffer problem
Galvin and various other resources only allow either the producer or the consumer to access the buffer at a time, the common code is as follows:
...
0
votes
2answers
61 views
How a swapper manipulates entire processes in the operating system?
The below-given lines are written in the book of the operating system (Page -307), details of the book are as follows:
OPERATING SYSTEM PRINCIPLES, 7TH ED., Abraham Silberschatz, Peter Baer Galvin, ...
0
votes
0answers
9 views
IoT OS running on top of Ubuntu?
I am new in the field of IoT OS and I saw TinyOS, Conitki etc. can be installed on top of Ubuntu. Its not clear to me how these OSes are able to run on top of Ubuntu without any Hypervisor? Can ...
5
votes
2answers
112 views
Why do OS locks require hardware support?
I just read the chapter on locks in the book Operating Systems: Three Easy Pieces, and it discusses an implementation of locks (see in Figure 28.9) that involves a test-and-set hardware instruction.
...
2
votes
1answer
88 views
Early Deadline First (EDF) scheduling in real-time systems feasibility test proof
I am trying to prove Theorem 6.2 on page 127 of the book Real-Time Systems by Jane W. S. Liu: http://www.cse.hcmut.edu.vn/~thai/books/2000%20_%20Liu-%20Real%20Time%20Systems.pdf
It is based on Early ...
2
votes
1answer
58 views
How were operating systems even made?
By that, I don't mean what is needed to make an operating system. I know that OSes are built on top of kernels and whatnot. But what I mean is, it wasn't like anyone could just "program" the ...
3
votes
1answer
72 views
What does starvation freedom exactly mean?
Galvin offers the following definitions of starvation:
Indefinite blocking, or starvation, a situation in which processes wait indefinitely within the semaphore.
A major problem with priority ...
0
votes
1answer
50 views
I want to learn more about computer science. Where should I start?
Hello computer scientists,
I am a mathematician. I have taken some undergraduate courses in C++, Python, assembly language, boolean algebra, logic, graph theory, etc. I would like to learn more about ...
0
votes
1answer
82 views
Is vmlinux a virtual machine?
From Wikipedia,
On Linux systems, vmlinux is a statically linked executable file that contains the Linux kernel
Does that mean vmlinux is a virtual machine that runs Linux? I am really confused.
0
votes
0answers
9 views
the difference between Idle point and Idle slot
I believe that I don't understund well the difference between an idle processor point and an idle slot
Thanks
0
votes
0answers
62 views
Gantt chart for Round Robin Scheduling using only arrival and completion time
I had the following question in my Operating System 'CPU- Scheduling' assignment-
4 processes A,B,C,D have estimated time of completion of 5,7,9,11 ns each. They are scheduled in a round-robin fashion ...
0
votes
1answer
67 views
Confused between the terms Process and Process Control Block
I was reading about the Long term scheduler, when I read that when memory is not enough and load on the CPU due to multiprogramming is too high, a process might be moved to secondary storage space (...
0
votes
0answers
21 views
why you couldn’t use mmap to manage a rdbms buffer pool - or the whole rdbms itself just like NoSql stores?
why you couldn’t use mmap to manage a rdbms buffer pool - or the whole rdbms itself just like NoSql stores?
I see that Cassandra, Hbase, Elastic do use mmap so why not use the same strategy for an ...
0
votes
0answers
30 views
Round robin doubt
Consider a system running ten I/O-bound tasks and one CPU-bound task. Assume that the I/O-bound
tasks issue an I/O operation one for every millisecond of CPU computing and that each I/O operation ...
0
votes
0answers
31 views
Operating system scheduling doubt
Consider a uniprocessor system executing three tasks T1,T2 and T3 each of which is composed of an infinite sequence of jobs (or instances) which arrive periodically at intervals of 3, 7 and 20 ...
1
vote
2answers
70 views
Why can't we compile 8086 Assembily for all OSs from any OS?
If Mac OS, Linux, and Windows (mostly) all use Intel's 8086 64 bit instruction set, why can't we compile 8086 64 assembly from any operating system to any other operating system? (e.g. compile a Mac ...
0
votes
0answers
25 views
A 32 – bit wide main memory unit with a capacity of 1 GB is built using 256M X 4-bit DRAM chips
A 32 – bit wide main memory unit with a capacity of 1 GB is built using 256M X 4-bit DRAM chips. The number of rows of memory cells in the DRAM chip is 2^14. The time taken to perform one refresh ...
0
votes
2answers
45 views
Storage in registers
Whenever CPU needs the data, it gives the address of that word to the RAM via bus, then the RAM generated the copy of that word and sends to the registers via bus. Why can't the RAM send the original ...
