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Questions tagged [operating-systems]

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

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2
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2answers
9k views

Difference between multitasking, multithreading and multiprogramming

I was a little confused between these three terms Multitasking, Multithreading and Multiprogramming Although every one means executing different lines of codes, and for every one we need something ...
0
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1answer
707 views

compiler interaction with OS [closed]

I want know if compiler interacts with operating system during compilation process.And if yes then which part of compiler interacts with which part of operating system
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1answer
1k views

Does virtual address space resides in virtual memory?

I have several confusion like : Does virtual address space resides in virtual memory ? Does each process has its own virtual address space like each process has its own virtual memory and own page ...
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1answer
127 views
0
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1answer
292 views

Task Manager Performance tab in windows [closed]

I do not understand the following options in windows. Could any one explain
0
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1answer
3k views

What happens when time slices are too short or too long?

What bad things can occur when the lengths of the time slices in a multitasking system are too small? What can happen when they are too big? How should the length of the time slice be chosen?
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1answer
5k views

Valid-invalid bit in a process page table

Valid-invalid bit is used to indicate whether a page in a process’s page table is valid or not. Why is it needed? Does that mean that each page table has a certain minimum size, i.e. it can ...
1
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1answer
820 views

Do Kernel-Mode Windows Services Considered Part of Kernel?

I learned that there are two types of services in Windows , one called -service- which is in user-mode , other is called -driver service / device driver- which is in kernel-mode. What I wonder is , ...
6
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3answers
3k views

Solutions to synchronization problem need to be executed in critical section

I was reading about synchronization problems for cooperating processes and i learned that only hardware solutions like test_and_wait() and ...
7
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2answers
3k views

Microsoft Singularity : why closed [closed]

I'm talking about this one research project: but MS closed it in 2008. I've read many articles about it, about high perfomance (30+% faster against tradinional monolithic kernels), much more secure ...
0
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1answer
1k views

How is the implementation of pipes in a OS

I understand that a pipe is a form of IPC where a process creates a link to communicate with some other process (a child maybe), taking each one a end of the pipe. File descriptors are created for ...
50
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2answers
21k views

What happens to the cache contents on a context switch?

In a multicore processor, what happens to the contents of a core's cache (say L1) when a context switch occurs on that cache? Is the behaviour dependent on the architecture or is it a general ...
0
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1answer
68 views

How many virtual machines run inside MS Windows?

In my Computer Systems (first year) module as part of my EE degree I'm studying virtual machines, memory management, hardware abstraction etc. I have come across the information that the OS creates ...
1
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1answer
167 views

Good “serializer” ADT implementations for Synchronization

I am looking for a library which provides a "serializer" ADT for synchronization. (http://courses.cs.vt.edu/~cs5204/fall99/Summaries/Concurrency/serializers2.html) Googling leads me to nowhere, ...
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0answers
1k views

want to know concept behing Multilevel paging

In order to use large size page table hierarchical paging is done . In case of two level page table scheme . for : logical address space - 32bit - $2^32$ page size - 4kb i.e $2^12$ It is mentioned ...
2
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1answer
158 views

about scheduling in operation system

In FIFO: when process get cpu time and then go to IO. What happend in the time it is in IO? another process can run? After finishing IO it continue or "loss its turn"? Why FIFO give priority to cpu ...
4
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1answer
1k views

Why do some filesystems have fragmentation and others don't?

I try to understand why fragmentation is a problem for NTFS and FAT but not when using inodes. In all cases, files are not necessarily stored in a contiguous fashion so I don't see the problem for the ...
1
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1answer
1k views

How a program is copied to RAM from harddisk

I know that for executing a program, it should be copied to RAM. But the problem is whole of it may not be copied always. Since the size of the RAM is limited, there is mechanism called virtual ...
2
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4answers
140 views

Cross platform apps and programing languages…how is it done?

I always wondered how various certain languages like Java, HTML5 and browser extensions are made with cross platform(operates and functions the same, regardless of OS, being Linux/Windows/BSD not ...
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1answer
287 views

clarification about Algorithm of page replacement LRU with reference bits

Studying LRU approximation Algorithms I think to have not understand how it works, for example: ...
-2
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1answer
310 views

General question about how CPUs send and receive data/bytes to hardware?

Realize I didn't mention x86 or any more details to make this non-specific to any platform, but to just get a general idea of how this is done(this is also a long question with a lot of details). I ...
3
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1answer
2k views

How does a program execute with respect to the operating system?

I am reading Operating Systems by William Stallings 6th edition and I came across this text, Program execution: ...
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2answers
4k views

Disk scheduling and process scheduling

Whats the diffrence between Disk scheduling and process scheduling? I mean i know the roles of disks and processes, but it seems to me they both have the same aim. to reduce monopolies, they even both ...
1
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1answer
809 views

concurrency and hardware

I've a couple of questions that I need answers for. What I am looking for here is the outline of the answers. Not necessarily the exact complete answer. I can do that. The question is that common ...
1
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1answer
896 views

Hardware interrupts from keystrokes

If there is an interrupt from every keypress (or one for keydown, one for keyup, one for keypress?) how does the OS handle so many interrupts at the same time. A person typing at 120WPM would be ...
7
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4answers
7k views

Is the 2nd parity bit in RAID 6 a simple calculation?

I'm trying to understand how the 2nd parity bit or byte is set in RAID 6. I'm reading a paper by H. Peter Anvin, and it goes into Galois field algebra, which is somewhat new to me. Anyway, a rep from ...
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2answers
3k views

What mechanisms prevent a process from taking over the processor forever?

Suppose a process keeps running code (e.g. an infinite loop). How can other programs take over? What prevents the process from remaining active forever?
2
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1answer
5k views

SSTF disk scheduling algorithm? What if lowest seek times are equal in either direction?

Using the Shortest-Seek-Time-First (SSTF) disk scheduling algorithm (where we select a request with a minimum seek time from the current head position), what happens if the requests in both directions ...
3
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2answers
1k views

Dangerous interrupts

Let's say we have a fictional operating system in the user mode. Whenever an interrupt or a trap occurs, the os would switch to the Kernel mode jumping to the address determined from the interrupt ...
6
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1answer
625 views

Variation of the dining philosophers: is the standard solution still valid?

I have a problem that is almost equal to the standard one of the dining philosophers, but has a quirk: while a philosopher thinks, he still holds the fork on his left. If after the period of thinking ...
0
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1answer
110 views

How Does Dynamic Heap Storage Have Something to Do with Heap?

There are three typical ways to allocate memory for programs: static, stack and dynamic heap. However, when I look at the implementation of dynamic heap memory allocation from wikipedia , what I found ...
9
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2answers
1k views

Round-robin scheduling: allow listing a process multiple times?

In a round-robin scheduler, adding a process multiple times to the process list is a cheap way to give it higher priority. I wonder how practical an approach this might be. What benefit does it have ...
2
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1answer
169 views

Process state in multi threaded process

What would be the process state in a multi threaded process, in which threads are in different states (running, waiting, blocked etc)
5
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1answer
342 views

What is the difference between a module in a monolithic kernel and a server in a microkernel?

I´m not exactly sure what kind of impact these two things have on kernel design. Are servers more flexible because of running in user space, for instance, and does adding a module require a new build ...
5
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2answers
239 views

What if the electricity goes off while a file is being renamed?

Suppose I'm renaming a file and the electricity goes off right in the middle. Naively, it looks like the file could be in some “half-renamed” state. Maybe the name would have half the old name and ...
7
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1answer
242 views

What techniques exist for energy-efficient computing and networking?

I am currently reviewing the potentials of cloud computing regarding energy efficiency and green IT. In connection with this review I am having a look on techniques for increasing energy-efficiency in ...
7
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1answer
2k views

How are threads implemented in different OSs?

I was reading Linux Kernel Development by Robert Love, where I came across this Linux takes an interesting approach to thread support: It does not differentiate between threads and normal ...
2
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1answer
520 views

Massalin's Synthesis Quajects equivalent to ASM generating macros used in Game Oriented Assembly LISP?

Alexia Massalin's Dissertation on Synthesis was a Phd thesis on Operating Systems that contained a concept called 'Quajects' (see Chapter 4). This is some additional commentary on the Phd Thesis. ...
11
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1answer
5k views

Swap space management during pure demand paging

The following is a doubt that I came across while doing a OS home assignment - however, it seems more concept-based than a straightforward coding question, so IMHO I don't think the homework tag is ...
9
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4answers
13k views

What is meant by interrupts in the context of operating systems?

I've decided to read Operating Systems Concepts by Silberschatz, Galvin Gagne (8th edition) over the summer. I've gotten to a topic that's confusing me - interrupts and their role as it relates to ...
4
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1answer
132 views

Requirements for emulation

What are the complete specifications that must be documented in order to ensure the correct execution of a particular program written in Java? For instance, if one were archiving a program for long-...
6
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1answer
2k views

How to interpret “Windows - Virtual Memory minimum too low” from a CS student point of view?

On my old 256MB RAM, pc I get this message. (I guess it is quite common) Windows - Virtual Memory minimum too low Your system is low on virtual memory. Windows is increasing the size of your ...
19
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4answers
1k views

Does cooperative scheduling suspend processes when they perform an I/O operation?

Many operating systems references say that with cooperative (as opposed to preemptive) multitasking, a process keeps the CPU until it explicitly voluntarily suspends itself. If a running process ...
12
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1answer
4k views

What is the purpose of M:N (Hybrid) threading?

In other words, what advantages does Hybrid threading have over 1:1 (kernel only) and N:1 (user only) threading? This is a follow-up to What is the difference between user-level threads and kernel-...
5
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1answer
63 views

Which instruction yields atomicity in this expression that makes the result 2?

I am reading about atomicity and came across the following scenario ...
11
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4answers
213 views

Why store self and parent links (. and ..) in a directory entry?

Consider an filesystem targeted at some embedded devices that does little more than store files in a hierarchical directory structure. This filesystem lacks many of the operations you may be used to ...
18
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3answers
1k views

Clever memory management with constant time operations?

Let's consider a memory segment (whose size can grow or shrink, like a file, when needed) on which you can perform two basic memory allocation operations involving fixed size blocks: allocation of ...