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Questions tagged [interrupt]

157 questions
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What are software and hardware interrupts, and how are they processed?

I am not sure if I understand the concept of hardware and software interrupts. If I understand correctly, the purpose of a hardware interrupt is to get some attention of the CPU, part of implementing CPU multitasking. Then what issues a hardware…
Tim
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How is an Interrupt handled in Linux?

I just know that Interrupt is a hardware signal assertion caused in a processor pin. But I would like to know how Linux OS handles it. What all are the things that happen when an interrupt occurs?
Navaneeth Sen
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Why can't ed be exited with C-c?

The program ed, a minimal text editor, cannot be exited by sending it an interrupt through using Ctrl-C, instead printing the error message "?" to the console. Why doesn't ed just exit when it receives the interrupt? Surely there's no reason why a…
Lily Chung
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How does the Linux kernel handle shared IRQs?

According to what I've read so far, "when the kernel receives an interrupt, all the registered handlers are invoked." I understand that the registered handlers for each IRQ can be viewed via /proc/interrupts, and I also understand that the…
bsirang
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What is the relationship between system calls, message passing, and interrupts?

I am reading the Wikipedia article for process management. My focus is on Linux. I cannot figure out the relation and differences between system call, message passing and interrupt, in their concepts and purposes. Are they all for processes to make…
Tim
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Do system calls actually "interrupt" the CPU the same way that hardware interrupts do?

I'm trying to get a deeper understanding of how system calls and hardware interrupts are implemented, and something that keeps confusing me is how they differ with respect to how they're handled. For example, I am aware that one way a system call…
rb612
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What is interrupted system call?

I am reading APUE and the Interrupted System Calls chapter confuses me. I would like to write down my understanding based on the book, please correct me. A characteristic of earlier UNIX systems was that if a process caught a signal while the…
Rick
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How does make continue compilation?

I know that I can interrupt a make process anytime without having to recompile the entire source tree again. As I know, make only compiles a target if it's not compiled yet, or the source code is modified after the last compilation. But if I…
psimon
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Is there a utility that interprets /proc/interrupts data over time?

Is there something out there? Like top is for ps
lisak
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What's the policy determining which CPU handles which interrupt in the Linux Kernel?

I've been reading Linux Kernel Development and there's something that's not entirely clear to me -- when an interrupt is triggered by the hardware, what's the criterion to decide on which CPU to run the interrupt handling logic? I could imagine it…
devoured elysium
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"Remote function call interrupts" (CAL in /proc interrupts). What is it?

I'm running a test program which generates a large number of threads and asynchronous I/O. I'm seeing very high counts of these interrupts in /proc/interrupts, the program cannot scale beyond a certain point because CPUs are 100% saturated with…
twblamer
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How to debug causes of excessive ksoftirqd resource usage?

man ksoftirqd indicates that: If ksoftirqd is taking more than a tiny percentage of CPU time, this indicates the machine is under heavy soft interrupt load. I'm working with a Debian Wheezy system under generally high system utilization in…
mrP
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How to deduce the nature of an interrupt from its number?

I'm trying to boot/install Linux for learning purposes, using an older PC (HP Pavilion Elite m9660de). The following message is the first thing that shows up when booting (Ubuntu and Fedora, both from a bootable USB-stick and a fresh…
Stefan
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Why doesn't SIGINT work on a background process in a script?

I have the following in a script: yes >/dev/null & pid=$! echo $pid sleep 2 kill -INT $pid sleep 2 ps aux | grep yes When I run it, the output shows that yes is still running by the end of the script. However, if I run the commands interactively…
eZanmoto
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Ctrl + c will not kill process

I have looked for answers and so far have found nothing to answer my question. I am currently logging in to my Ubuntu server and upon running a process I can not run any of the interrupts on it. Here is my stty -a: user@Ubuntu1:~$ stty -a speed…
user700786
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