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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...