Questions tagged [operating-systems]
Questions about the principles of software that interfaces between hardware and applications.
568
questions
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1answer
16 views
Operating System code suffers more cache misses than user code
I was going through the text of the book Computer Architecture: A Quantitative Approach. It has a section in Chapter 5 where it discusses the fact that OS code undergoes more cache misses as compared ...
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0answers
15 views
Does input type=“file” selection support url ( upload from web ) ? -html [closed]
I wonder can I use the option of input type="file" in html to upload from url ( web/ftp etc. ) ? Is there option to it? To more explain, I want to select zip file with url and uoload it to website....
2
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0answers
32 views
Why can't OS's keep audio and video recording in sync?
It seems every program that purports to record webcams fails to keep audio and video in sync. Moreover, there are probably man millenia being spent by people trying to correct for this during editing....
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2answers
68 views
Is this a deadlock?
Consider we have two processes P1 and P2. There are also two semaphores M and N which are initialized to zero. Here's how they execute:
...
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0answers
25 views
Deadlock: can the processes know about deadlock occurrence
Deadlock can happen when two processes are waiting for resources held by each other. Here can the two processes know that they are waiting for each other to release resources?
2
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2answers
68 views
Why doesn't everyone use distributed operating systems?
As requested by a moderator, this question as been separated from my question about microkernel-based operating systems.
In the 1980's, the team that developed C and Unix developed a distributed ...
3
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1answer
85 views
Why doesn't everyone use microkernel-based operating systems?
From what I have read on operating systems, the impression I have been receiving is that, for at least 30 years, "everybody has known" that microkernel-based operating systems are "better" than ...
1
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1answer
12 views
Is “capability-based security” vs “hierarchical-protection-domain based security” a false dichotomy?
The wikipedia page on capability-based security states:
Capability-based security is to be contrasted with an approach that uses hierarchical protection domains.
However, in order to implement ...
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0answers
17 views
Journey of a process from compilation to execution [closed]
I am reading operating system, and after reading some topics (Processes, Main Memory management) I got somewhat confused. I have knowledge about certain things but I am not able to combine and ...
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0answers
24 views
Deadlock in resource allocation graph
I am unsure if there is a deadlock in this particular graph.
Not sure if P2 and R2 make a cycle.
As well as P2 - R3 - P1 - R1 - P2. It seems there is a cycle, but not sure if there is a deadlock ...
4
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0answers
34 views
Is there a OSI model equivalent for describing the abstract layers present in performing a computation for an operating system?
In describing where a system vulnerability exists, I often find a need for a model that partitions a operating system and its components into abstraction layers. Similar to how the Open Systems ...
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0answers
15 views
Research papers related the Android OS's Adaptive Battery and Screen Brightness
I want to read the details of the Adaptive Battery Optimization and Adaptive Brightness techniques used in the Android operating systems as mentioned in this wired.co.uk article. I tried looking for ...
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2answers
37 views
Does pre-emption of a process occur when that process is busy waiting?
I was reading about Peterson's Solution for Synchronisation. Let's assume the two shared variables to be int bool flag[2] and ...
0
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0answers
12 views
External fragmentation of memory
Im trying to calculate the external fragmentation of a memory with the content
UFFFUUFFUU
where U is used, and F is free. Im confused as to how to do this, when i dont know the number that Used is ...
0
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0answers
10 views
How Are Segment Descriptors Used
I am following through James Molloy OS tutorials and I can't get my head around the GDT. I understand that it contains entries that describe segments, what I don't understand is,how are the segment ...
17
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13answers
9k views
Why do we need full-fledged workstations running massive OSes with massive software?
I've grown up with computers. While watching old computer TV programmes and documentaries and reading the news about constant issues with these modern systems -- everything from the sheer amount of ...
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0answers
16 views
Doubt in effective memory access time in case of n level paging + TLB
I am getting confused with calculation of EEMAT(Effective memory access time). I decided to close the book and think on my own and make an equation. Please see whther this is correct or not. I thought ...
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0answers
27 views
how worst fit better than best fit?
I am a beginner. I have recently started studying OS.
In textbook, it is written as best fit is worse than worst fit. Reason - external fragmentation.
IMO,in case of variable partionioning, best ...
2
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1answer
32 views
doubt in pipelining
I am not from cse but trying to learn computer architecture on my own. Please clarify the following.
In case of pipelining, each stage or subcomponent or subtask is assumed to be done in 1 CPU ...
0
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1answer
31 views
When does a semaphore issue a wait and when does it issue a signal?
In my textbook, Operating Systems: Internals and Design Principles (9th Edition) by William Stallings in chapter 5, it explains how semaphores work:
The fundamental principle is this: Two or more ...
0
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0answers
8 views
Study of cache behaviour of algorithms on Virtualbox
I want to study certain cache oblivious algorithms and cache behaviour of some other algorithms I wrote in general.
I want to understand, is it advisable, if I do this study in an virtualized ...
0
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0answers
9 views
Are there any models of operating systems which don't require rings of privileges, that are also secure?
I am working on a simple operating system in JavaScript and have noticed that there are two kinds of processes: the "main" process (or "kernel" process), and all the other processes. Basically they ...
1
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3answers
72 views
How many registers does a computer *need*?
I read about Why does a processor have 32 registers?, and others. Currently I am messing around with an OS in JavaScript, and wondering how many registers -- or more specifically, how many temporary ...
1
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1answer
16 views
Paging - access less than a page of memory
I'm having a bit of trouble understanding how less than a page of memory can be used.
From what I understand, memory is given out in page size chunks - say pages are 4096 bytes, and 4 bytes are ...
1
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0answers
32 views
Given only TLB Lookup time, and memory access time, can the TLB hit rate be negative?
I'm given the following problem:
TLB lookup time is given as 8ns and memory access time for a computer
system is given as 40ns. What should be the TLB miss rate to achieve
effective memory ...
0
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1answer
42 views
Can timestamp be used in synchronization of processes having Race Condition?
I am wondering whether timestamp can be used to solve process synchronization problem, when race condition occurs? Below is an algorithm for entry as well as exit sections for every process who wants ...
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0answers
10 views
What IaaS services are needed in order to run a server?
I have just learn't about Iaas, Paas and Saas and I was wondering whether a business can host a server by using IaaS services. However, many IaaS providers such as AWS, Azure and Google provide ...
0
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0answers
33 views
Does exec cause a context switch?
If we start a new process with
exec('process-2')
Does this cause an immediate context switch in order to halt the current process and then start the new '...
0
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1answer
32 views
Why no context switch is required in case of spinlock in operating systems?
I have a query regarding the fact that how Spinlocks are advantageous in terms of context switching ?
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1answer
67 views
What is the name of this experimental OS?
I am trying to find an OS that had a network to verify it's users. It classified itself in classes going from greatest signifigance to least, and the names were galaxy, system, planet, comet etc.
I ...
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0answers
20 views
What assumptions do I have to make about monitors (in OS)?
I am taking a course in Operating Systems. I am going through old exams and there is a question about monitors. We are supposed to give a solution for the producer-consumer problem using monitors. ...
13
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2answers
6k views
What is a GPU year?
I am reading papers in machine learning and they say things like, "This computation took $x$ number of GPU years".
What is a GPU year? How long is that?
2
votes
1answer
78 views
How can a 32bit CPU have an addressable memory size of 16TB?
Frequently, on a 32-bit CPU, each page-table entry is 4 bytes long, but that
size can vary as well.
A 32-bit entry can point to one of $2^{32}$ physical page frames.
If frame size is 4 KB (212), ...
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0answers
28 views
Expected value of next CPU burst using exponential averaging
The burst time is needed for Shortest Job First (SJF) and Shortest Run Time First (SRTF) scheduling. To get the approximate burst time, we use the equation
$$\tau_{n + 1} = t_n + (1 - \alpha)\tau_n$$
...
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0answers
13 views
Does a safe state ensures there will never ever be a deadlock?
In Banker's algorithm of deadlock avoidance, if one can obtain a safe state, does that necessarily mean there will never be a deadlock, or is there still some way that the system could fall into a ...
0
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1answer
49 views
Is logical address generated by CPU and MMU same if Physical and Virtual address space are same?
The system has same physical and virtual address space i.e. 32-bit. Are the logical address generated by CPU and address generated by MMU same?
0
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1answer
48 views
Lack of Stack Pointer Register
Suppose a processor lacks STACK Pointer Register. But, It does have STACK.
Then, in my opinion, a program will still be able to call subroutines but, will be unable to return back from the subroutines....
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0answers
27 views
How many page-table entries can fit into TLB space
I am looking to calculate how many page-table entries can fit into a corresponding TLB space (Translation Look-aside Buffer ). I just want to make sure I am getting the calculation right, as I fear I ...
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0answers
14 views
How many page-table entries are needed in case the program uses the whole logical address space
Say I have:
page size = 2^12 bytes
physical memory = 2^24 bytes
logical address space = 2^32
How many page-table entries are needed in case the program uses the whole logical address space?
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1answer
55 views
Converting physical address to logical
In 8-bit address space there are 16 pages and the page table stores:
68792EA51BD3CF04 (hex)
The physical address is 39h, what is the corresponding logical address?
I have literally no idea what to ...
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0answers
27 views
Doubts on Virtually Indexed,Physically tagged Cache
I tried referring a few material (videos on youtube and this link as well), but I still couldn't wrap my head around the concept.
My (brief) understanding of the Virtually addressed, Physically ...
0
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1answer
63 views
How are hardware interrupts handled?
I have read that a hardware interrupt is handled asynchronously by the CPU, which means that the interrupt signal may arrive at any point of time with respect to the CPU clock cycle. Now, this means ...
0
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1answer
49 views
Software management of TLB misses?
I'm reading an OS textbook and it was talking about TLB misses being handled by software. I'm very new to all this by the way. So there's a context switch to some kernel procedure. But surely in this ...
0
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1answer
100 views
What is a batch based interface? [closed]
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 ...
0
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1answer
85 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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2answers
59 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 ...
0
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0answers
16 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-...
0
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1answer
32 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
44 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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0answers
60 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 ...
