The tag has no wiki summary.

learn more… | top users | synonyms

1
vote
2answers
32 views

What happens to the signals requested recursively?

People often hit Ctrl + c or Ctrl + z to cancel or abandon the job if the process gets sluggish, in this case which of these signals get processed, the first one or the last one? is each signal ...
0
votes
0answers
10 views

Why would attempts to bind affinities for rcu kthreads fail?

I am trying to get full tickless mode working on my box on Ubuntu kernel 3.10.39. I am running the following command: for i in `pgrep rcu` ; do taskset -pc 0 $i ; done It seems to work on some of ...
3
votes
3answers
41 views

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 ...
3
votes
2answers
61 views

How to programatically detect when a device raises an interrupt?

How to programatically detect when a device raises an interrupt? This can be when a device is connected or disconnected. And also this case: for example: when a finger is held over a fingerprint ...
1
vote
0answers
40 views

How does an X86 Linux system maintain the system time, when no NTP etc. is in play?

When an x86 Linux system is powered up and running, how does it keep track of software time? E.g. is it incrementing a software counter based on hardware interrupts from the RTC, or is there some ...
8
votes
3answers
319 views

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 ...
0
votes
0answers
34 views

Execute snippet of code when key is pressed [duplicate]

I want to create a process in Linux which waits for some particular keys to be pressed and executes a snippet of code and goes back to sleep. How can I achieve this? Initially a process will be in ...
2
votes
1answer
78 views

Why EC2 instance spends all its time in “IRQ” and what to do about it?

I have an m1.small EC2 instance that is mostly just running Apache as a web server for several simple PHP web sites (that use RDS as a database). The server is constantly with a very high load average ...
2
votes
1answer
38 views

How to know if an IRQ value is free to use

If we add a device that does not support PNP (Plug-an Play), the manufacturer will hopefully provide explicit directions on how to assign IRQ values for it. However, if we don't know what IRQ value ...
2
votes
1answer
48 views

Minimizing hardware interrupts

I am using a modified Linux kernel as a soft real-time OS, on a system that has an architecture like this: CPU1 and CPU2 have 8 cores each. I have 4 processes that need to be run with minimum ...
1
vote
1answer
39 views

Linux Interrupts [closed]

I'm trying to write my own interrupt controller but I'm having some difficulties finding good documentation. Where can I find some information about interrupt management in Linux? To be more ...
1
vote
1answer
53 views

How does handling an interrupt affects a multi-threaded user space process?

Say, I put a breakpoint (int 3 from now on) somewhere in a user space process code. One of the threads hits the breakpoint... And what happens next? My judgement is: this is an interrupt, so it is ...
1
vote
0answers
217 views

How to configure FreeBSD to run headless without hitting high interrupt rates?

When running headless (without monitor, keyboard, mouse attached) FreeBSD versions 8.2, 8.3, 9.0 and NetBSD version 5.0 has known issues (FreeBSD PR 156596, NetBSD 46596) to generate extremely high ...
1
vote
1answer
260 views

High IO-APIC-fasteoi interrupt usage eth0

I believe this is due to an rsync cronjob which runs every 15 minutes. This is a RHEL 6 box running in ESXi. /proc/interrupts shows: 18: 3386804969 IO-APIC-fasteoi eth0 and the system load ...
1
vote
2answers
874 views

How to generate signal interrupt on a file descriptor in Linux?

How can I generate a signal interrupt on a file descriptor in Linux? Motivation is to generate a interrupt in userland as we have in microcontrollers. I'll have file descriptor for I/O, and want to ...
2
votes
1answer
214 views

Generate interrupts for purpose of stress testing

I'm testing the quality of a generated PWM signal on a Raspbery Pi. I would like to test how it behaves if there are lots of interrupts coming. Is there a way to fake interrupts or force 2000 ...
1
vote
1answer
167 views

What value is stored in linux xtime variable?

Whenever I print the value of /proc/interrupts the value of rtc0 in IRQ8 which is for RTC shows only 1 interrupt on CPU0. I have read that when booting the value of the xtime variable is stored from ...
2
votes
2answers
788 views

Can system calls be interrupted?

Please comment on the following sentence: On the standard Linux kernel without the rt patch, interrupts can't interrupt ongoing system calls. The reason why our machine doesn't stop working ...
2
votes
1answer
349 views

Are time interrupts always followed by a scheduler call?

When a timer interrupt occurred the ISR is called to service the interrupt. Is it okay to assume that every timer interrupt ends with a call to the scheduler on which process should continue running ...
2
votes
0answers
73 views

Which counter generates timer interrupts?

I did a iotop to observe the interrupts on my computer. This is the interrupt shown most often. 0 [PIC-edge time] 247 Ints/s (max: 389) I believe it's the timer interrupt, well since ...
0
votes
1answer
242 views

How to troubleshoot high kernel time (high network usage; high interrupts)

I've noticed that I have high kernel time when doing a lot of network traffic in Linux. I also noticed that 45% of my CPU is spent doing interrupts. How can I further troubleshoot this?
2
votes
1answer
206 views

Are threads which are executing blocking system calls awoken by interrupts?

I've been reading a bit about threads and interrupts. And there is a sections which says that parallel programing using threads is simpler because we don't have to worry about interrupts. However, ...
3
votes
2answers
800 views

Making a IRQ SMP Affinity change permanent

I have to change the smp_affinity of a interrupt permanently. The following code needs to be executed when the server reboots: echo "1" > /proc/irq/152/smp_affinity_list echo "2" > ...
1
vote
0answers
84 views

Further clarification as to whether interuppts are disabled in top-half handler or not [closed]

Recently I came across a note in an online post that states the following: In modern kernels, most of the differences between fast and slow interrupts have disappeared. There remains only one: ...
6
votes
2answers
5k views

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 ...
1
vote
0answers
193 views

Which softirq will execute if interrupt is generated on same line: preempted or new softirq?

Following is the sequence of events: interrupt generated at line 1. line 1 disable. ISR executed. Set sofirq bit 1 line 1 enable. softirq executes and suddenly interrupts come at line 1. softirq ...
4
votes
1answer
2k views

What does Linux's “nointremap” option do?

Ubuntu 12.10 alpha 2 works perfectly on my new 11" 2012 Macbook Air, but only when I boot with the "nointremap" option. Supposedly this is not good to use as a permanent solution. What exactly does ...
2
votes
0answers
469 views

“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 ...
0
votes
0answers
18 views

Can an interupt be processed by software, without hardware support? [duplicate]

Possible Duplicate: Can an interrupt be soley processed by software without harware support? Can an interrupt be processed by software without the need for hardware suppport? Assume a x86 ...
1
vote
1answer
192 views

Can an interupt be processed by software, without hardware support? [closed]

Can an interrupt be processed by software without the need for hardware suppport? Assume an x86 architecture.
5
votes
3answers
2k views

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 ...
7
votes
1answer
889 views

Interrupt sequence CTRL+C does not work for user

In any terminal operating under GNOME, if I press Ctrl+C, I only see a question mark. Same goes for Ctrl+Z. The output of stty -a | grep intr is: intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ...
9
votes
1answer
7k views

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 ...
8
votes
3answers
3k views

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 ...
3
votes
2answers
2k views

change interrupt smp_affinity

As you can see below, nvidia is sharing the intrerrupt and the interrupt is using only CPU0, how can I change the interrupt for nvidia, and how can I make it use both CPU's ? Here is an article ...
4
votes
1answer
2k views

What determines whether an interrupt is IO-APIC-edge or IO-APIC-level?

Looking at the contents of /proc/interrupts on an x86 Linux, I see that some of the interrupts are IO-APIC-edge while others are IO-APIC-level. I wonder what determines the interrupt type, is it the ...
2
votes
1answer
537 views

Is there a utility that interprets /proc/interrupts data in time?

is there something out there ? Like top is for ps
0
votes
1answer
1k views

What happens in the Top half and Bottom Half processing of Interrupts?

I would like to know more about Top half and Bottom Half processing in the Context on Interrupts. Could someone explain me the exact things happening in both scenarios.
3
votes
2answers
1k views

'fast interrupts' in Linux

as far as I know, Linux has 'fast interrupts', those that were requested with SA_INTERRUPT flag; fast interrupts are executed with all other interrupts disabled on the current CPU. But how does it ...
3
votes
2answers
1k views

re-entrency of interrupts in Linux

I was reading "Linux device drivers, 3rd edition" and don't completely understand a part describing interrupt handlers. I would like to clarify: are the interrupt handlers in Linux nonpreemptible? ...
16
votes
5answers
16k views

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?