Questions tagged [interrupt]

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Apart from USR1 and USR2, which signals can I safely use for custom interrupting behavior? (in python)

I have a complex application with USR1 and USR2 already defined as having a well-defined and not replaceable purpose. There are tons of different signals in linux. Might there be another one (maybe a ...
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0answers
2k 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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0answers
83 views

Is there a way to route interrupts from two Ethernet interfaces to separate cores?

I have a 10G ethernet adapter from Intel with two ethernet ports (x550-T2) installed in PCIe port of a Xilinx FPGA board running petalinux. I am testing network bandwidth by running simultaneous ...
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0answers
2k 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 When ...
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0answers
30 views

What mechanism is used by Linux (or hardware) to ensure that any interrupt capable device does not cause too many interrupts?

At the level of interrupts, one would think that there has to some way for a maximum rate to be defined. Otherwise, a malicious device might be able to slow down the system, by continuously giving off ...
2
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322 views

Shielding CPU from scheduler - How to move bound kernel threads from cores?

Suppose I have 4 physical cores (indexed 0-3) and I'm dedicating cores 1-3 to a shield for user applications and trying to steer all system threads onto core 0. I'm following the answers here and ...
2
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1answer
751 views

Unusual high load average (due to peak I/O wait? irqs?)

I have a problem with high load average (~2) on my (personal laptop) computer for a long time now. I am running Arch Linux. If I remember correctly, the problem started with a certain kernel update, ...
2
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0answers
161 views

Wifi card causing High interrupts on Fedora 24

I am running Fedora 24 on my MSI cx61 2QC laptop. Occasionally, one of the processor's core becomes monopolized by high irqs from the rtl_pci(wifi) card. The model of the wifi card is RTL8723AE. $ ...
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0answers
114 views

Trying to understand device tree entry for usart

I'm pretty new to device tree programming, I'm trying to understand the interrupts line that shows up in the device tree for SAMA5D36 USART dts definition: usart2: serial@f8020000 { compatible = "...
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0answers
1k views

kernel: hpet1: lost 19 rtc interrupts

I have this error that flooding my syslog every day. As a solution on arch linux forum is hpet=disable in kernel command line, but I think it is a bad idea and I searching for another solution. Is ...
2
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1answer
263 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
179 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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1k 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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295 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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0answers
29 views

Trouble with Legacy interrupts on new CPU

A legacy (IntA) interrupt works on an old CPU under Linux, but fails under the same Linux OS with a newer CPU in that system. I'm unsure if the problem is in the BIOS or in the Linux driver, as both ...
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98 views

Trying to use local APIC timer

I'm trying to use the local APIC timer to send interrupts after a certain interval (for a kernel module I am writing). This is not related to scheduling in Linux. I set the clocksource in Linux to ...
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0answers
281 views

how to use ftrace to function_trace a kernel modules interrupt?

I have a Banana Pi Arm device with 2 cores (1.2 GHz) running a Debian kernel which I enabled ftrace kernel debug options. I want to determine the amount of time spent in a kernel module function. The ...
1
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1answer
1k views

can't change value in smp_affinity

I am trying to set irq affinity on linux by changing the value in smp_affinity. When I echo the new value into the file, I don't get any error but when I read it back, the value remains unchanged. I ...
1
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1answer
176 views

difference between kworker/n and events/n

I'm learning how the kernel handles interrupt. Reading shichao's notes, I've found that events/n threads handle the work queue. At the same time, some documents in the internet (for example, this post)...
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0answers
41 views

Does the lack of kernel feature (XENFEAT_hvm_pirqs) cause RedHat EC2 interrupt issue?

I have a RedHat 6.5 on AWS EC2 running kernel 2.6.32.431, I have installed the ixgbevf driver with the minimum version the doc recommends. After configuration the system now has 2 queues(IRQs): grep ...
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634 views

Why do interrupted processes show up in nvidia-smi?

When ​I kill processes in terminal using C-c and run nvidia-smi, the process are still shown as "compute processes". These processes are no longer in the top resu​lts. I have to kill -9 to clean them (...
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306 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 /...
1
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1answer
135 views

Interrupt kernel process or another interrupt

How does ISR know 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 ...
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0answers
100 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 ...
1
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1answer
259 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
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1answer
741 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
95 views

About IRQF_DISABLED flags

I'm reading about a tutorial on request_irq, I'm new to this topic so I need some idea checking: When set, this flag instructs the kernel to disable all interrupts when executing this interrupt ...
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62 views

Interrupt handling with separate thread

The Situation A kernel driver handles interrupts coming from a CPU pin. The interrupt handler function wakes up a thread function which reads data from an interface. There is one interrupt per data ...
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83 views

Why does nohup command interrupt?

I put a command in .bash_profile file. The command is: nohup stdbuf -oL -eL sysdig -c spy_users 1>>/path/to/out 2>>/path/to/err & While I am working on terminal it appears: [1]+ ...
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1answer
115 views

why local CPU must have interrupts enabled, otherwise kernel preemption is not performed?

I read the book "understanding the Linux kernel". I cannot understand a sentence,that is ,the local CPU must have local interrupts enabled, otherwise kernel preemption is not performed. What is the ...
0
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1answer
765 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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1answer
1k 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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0answers
332 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 ...