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5
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1answer
46 views

Ctrl+c and Ctrl+z to interrupt/suspend jobs

To kill a hanging job, I use Ctrl+c, to send an interrupt signal to the hanging job. Sometimes this wouldn't stop the job, at least not immediately. I can then use Ctrl+z to suspend the job and then ...
1
vote
0answers
15 views

Why I am not able to bind the interrupts with code LOC, IWI, RES when irqbalance is disabled?

On Ubuntu 14.04, I am trying to bind all the interrupts to core 0 and 1 out of 4 cores. I have disabled the irqbalance daemon via file /etc/init/irqbalance.override. Then I went to every interrupt in ...
0
votes
0answers
9 views

This name appears in multiple /proc/interrupts

The name of the interrupt appears as follows: Multiple.. (85:exynos4210-uart) root@test:~# cat /proc/interrupts CPU0 CPU1 CPU2 CPU3 28: 3543629726 1086578047 3268216812 ...
0
votes
0answers
10 views

Interrupt kernel process or another interrupt

How ISR knows that it interrupts process in kernel mode or another interrupt (which enables further interrupts) - of course in kernel mode too. If this question is very wide, please aim to Linux on ...
0
votes
2answers
58 views

Main stacks in Linux

What are the main stacks in Linux? I mean for example when interrupt occurs what stack will be used for it? Also what is the difference between user process and kernel process stacks? Please, can be ...
1
vote
0answers
17 views

What can interrupt execution of threads which are pinned to cores?

I do low-latency application development and I use isocpu and set thread affinity to reduce (eliminate?) context switching during my critical threads. However, I am unsure what other types of ...
2
votes
0answers
33 views

Is “top” accounting for Kernel Interrupts?

I have a simple interrupt that is triggered by a GPIO-input. The IRQ only increments a variable and returns. When I turn the frequency of the interrupts up to somewhere around 10-20 kHz, the system ...
6
votes
4answers
320 views

How can I handle SIGINT trap with a user prompt in shell script?

I am trying to handle SIGINT/CTRL+C interrupt in such a way that if a user accidentally presses ctrl-c, he is prompted with a message, "Do you wish to quit?(y/n)". If he enters yes, then exit the ...
2
votes
1answer
669 views

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 ...
0
votes
0answers
15 views

GPIO edge-file missing

I have exported some GPIOs in sys/class/gpio but when I look into the GPIO directories i cant find the edge file. I only see value, direction and a few other files. what does that mean. Is it in any ...
1
vote
1answer
467 views

What happens after a page fault?

When a page fault occurs in a Linux system, the interrupt-handler has to figure out the reason why the page fault happened. But how ? Is there anywhere a special number for that !? If yes, where is ...
0
votes
0answers
59 views

Stack pointer of the interrupt stack

Linux kernel has separate stacks for user mode and kernel mode process and also some special stacks. One of this special stacks is interrupt stack with the size 16 kilobytes placed in the ...
1
vote
1answer
61 views

Threads vs interrupts

What does it mean when threads are time-sliced? Does that mean they work as interrupts, don't exit while routine is not finished? Or it executes one instruction from one thread then one instruction ...
1
vote
2answers
76 views

How to interrupt uninterruptible program?

If I run mysqld from the command line, it displays some startup messages, and then stops responding. It doesn't produce output, and ignores any input, and there seems to be no way to get rid of it. ...
0
votes
0answers
176 views

default cpu affinity

On a CentOS 6 system with 32 cores, what could make all processes run under core 0 only? This is a system running nothing but a few stunnel processes actively. This is not a system we would set IRQ ...
0
votes
1answer
127 views

Cannot compile device tree blob due to missing node/label

I'm trying to create a petalinux image using the petalinux SDK. After I start a build I get an error when the process tries to build the system.dtb The error is "(phandle references): Reference to ...
1
vote
2answers
98 views

Triggering hardware interrupts by connecting parallel port pins 9 and 10 does not work

I want to trigger hardware interrupts as described in the book Linux Device Drivers by connecting pins 9 and 10 with a wire. I tried that but apparently there's no interrupt beeing triggered: cat ...
1
vote
0answers
286 views

What is the difference between Local timer interrupts and the timer?

When I do cat /proc/interrupts on my multicore x86_64 desktop PC (kernel 3.16) I see this: 0: 16 0 IO-APIC-edge timer LOC: 529283 401319 Local timer interrupts ...
2
votes
2answers
92 views

Is there any Syscall table just like Interrupt Table?

Are the system calls like fork(), exit() saved in some kind of function pointer table , just like the Interrupt Descriptor Table ? where does my OS go when I call my fork() or exit() ? I guess this ...
1
vote
1answer
156 views

What is the functionality of SCHED_SOFTIRQ in linux?

Who raises this softirq? Is it raised on every time tick( based on timer interrupt?) Does this make the kernel to shedule a runnable process? If yes, how does the handlers of lower priority softirqs ...
0
votes
0answers
91 views

keyboard still working after calling free_irq(1, NULL);

I'm developing a kernel module which free the IRQ number 1 in order to disable the keyboard in Intel architectures. according to wikipedia the IRQ 1 is used for keyboard. but after building and ...
0
votes
1answer
107 views

Force ping to write before interrupt

I am trying to get ping to continuously write some times to a file. When I run $ ping 10 10.1.10.28 | perl -ne '/time=(\d+\.\d+)/ && print "$1\n"' It returns one number every several ...
2
votes
1answer
342 views

Does each network packet cause an interrupt to CPU?

While I know that lot of packet processing(CRC calculations, packet segmentation handling, etc) can be offloaded to NIC, then does each packet still cause an interrupt to CPU? Is there a difference if ...
0
votes
1answer
32 views

Changing touchpad interrupt

I'm using Arch Linux. Before Arch, I was using Kubuntu. I have a Intel i7 processor with 7200 RPM hard drive. When I'm installing software (not from package managers, but a big proprietary one such as ...
1
vote
2answers
157 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 ...
4
votes
3answers
1k 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 ...
4
votes
2answers
297 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
83 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 ...
9
votes
3answers
829 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 ...
3
votes
1answer
521 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
215 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
137 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
75 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
138 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 ...
2
votes
0answers
597 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
903 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
3k 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
470 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
346 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
2k 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 ...
3
votes
1answer
1k 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
130 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
571 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
659 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, ...
5
votes
3answers
2k 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" > ...
10
votes
3answers
11k 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
289 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
800 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 ...