Questions about the fundamental component of an operating system, which manages the allocation of resources to applications.

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1answer
30 views

What features should a critical section have to maximize performance?

Critical sections limit performance by constraining parallel execution and adding overhead. What features should a critical section have for improving performance?
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0answers
27 views

What are disadvantages of a Operating System that recognise file extensions ?

When Operating system recognise the file types It has several advantages like 1. avoid mistakes like trying to print a object file that produce garbage output but I can't think about disadvantages ...
2
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1answer
85 views

What is a student process?

According to Galvin and Silberschatz, 5 queues are maintained in multilevel queue scheduling, each for: System Process Interactive Process Interactive Editing Process Batch process Student ...
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0answers
65 views

Switching between user-level and kernel-level threads

After reading difference between user-level threads and kernel-level threads ,now I am in doubt of context switching.Context switching is managed by OS when switching between processes/threads but ...
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2answers
30 views

Handling TOCTTOU with system calls

What are some of the best practices when implementing system call functionality for handling/avoiding "Time of check to time of use" (TOCTTOU) security issues?
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1answer
15 views

Relation between Signals and Events

There are POSIX signals (linux man), and various event-based operating systems (such as TinyOS, most seem to be targeted at embedded systems). But the mechanisms seem very similar. Are the terms ...
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1answer
44 views

Are Time-sharing and multi-tasking operating systems same or different

My question is regarding time-sharing and multi-tasking systems. Time-sharing operating system assigns time slot to each task while multi-tasking OS runs various jobs in parallel. But as I get it, ...
6
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1answer
185 views

Writing a multitasking operating system for a processor without MMU

I've been thinking of writing a hobby operating system for some of the ARM processors. There are many popular single-board computers with ARM MPU, so I simply wanted to purchase one of those (choosing ...
9
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1answer
217 views

Performance of microkernel vs monolithic kernel

A microkernel implements all drivers as user-space programs, and implements core features like IPC in the kernel itself. A monolithic kernel, however, implements the drivers as a part of the kernel ...
12
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2answers
48 views

What are potential pitfalls with having a minimal kernel that runs managed code?

Suppose I want to build an operating system based on a very small native lower kernel that acts as a managed code interpreter/runtime and a larger upper kernel compiled to a non-native machine ...
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3answers
90 views

How does the processor find kernel code after an interrupt?

When an interrupt occurs, the processor preempts the current process and calls kernel code to handle the interrupt. How does the processor know where to enter the kernel? I understand that there are ...
18
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1answer
124 views

Can an interrupt handler be preempted?

Can a running interrupt handler be pre-empted by another interrupt handler? If this is possible, in which scenarios is this safe, and in which scenarios is it not? If this is not possible, why?
6
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1answer
279 views

Difference between hypervisor and exokernel

An hypervisor (1st type) is a software that creates and run virtual machines, managing guest's operative systems's requests to the hardware. An exokernel is an operative system kernel, that let's ...
3
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1answer
81 views

Session Memory in the Windows Kernel

While reading the paper Effective Data-Race Detection for the Kernel by John Erickson and Madanlal Musuvathi. I was stuck on a slightly tricky sentence. "Similarly, a range of kernel-address space, ...
0
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1answer
66 views

Is my understanding of kernels correct?

System: Application OS: Scheduler, VMM, IPC, FS Drivers, dispatchers, VFS The above would be a monolithic kernel. In a monolithic kernel all core OS functions are separate from user spaaaaaace. ...
2
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2answers
411 views

Is there a shell between the kernel and hardware

First and foremost, i know what a shell, kernel is. Now the dilemma. Today i had my systems viva in college. The examiner asked me is there a shell between the hardware and the kernel. Obviously, i ...
5
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2answers
1k 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 ...
3
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2answers
170 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 ...
4
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1answer
192 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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1answer
728 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 ...
16
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1answer
24k views

What is the difference between user-level threads and kernel-level threads?

After reading several sources I'm still confused about user- and kernel-level threads. In particular: Threads can exist at both the user level and the kernel level What is the difference ...
11
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1answer
2k views

Are all system calls blocking?

I was reading an article that describes the switch between user-space and kernel-space that happens upon a system call. The article says An application expects the completion of the system call ...