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Questions tagged [irq]

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Does the worst PCIe MSI interrupt latency jitter over 100us normal?

I try to figure out the values of interrupt jitter in Linux, especially in the worst cases. Two testbeds are considered, one is Raspberry Pi 4B, the other is a high-end PC with an intel i9 CPU and ...
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What's about tegra210_timer?

I have a NVIDIA Jetson Nano running Ubuntu 18.04 tegra. I noticed a high CPU usage of irq (about 26% per hour). Exploring about, I found it is related with this process: $ watch -n 1 cat /proc/...
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Maximum serial port speed in Linux

I installed a brand new xr17v358 serial card, which claims 25Mbps maximum. (For some reason this was the only card I could find that didn't top out at 1950s speeds. I'll settle for 1970s speeds in ...
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Give user permission to change priority of an IRQ/root process

Is it possible, in Linux, to allow an user to change the priority of a process owned by root? More specifically an IRQ process? For an embedded real-time application I want to raise the priority of ...
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“Diabling IRQ #9” error at boot in manjaro linux

Whenever i start my pc. I see this error "Disabling IRQ #9". I only have manjaro on my pc (no dual boot) and wanted to know the cause behind this problem. Sudo systemctl returns no error but ...
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How to monitor conflicts at serial/CPU level between usb sensors, serial transmission and UDP streaming

I have a ARM64 board running Ubuntu 18. The board runs a Python script that does the following: acquire data from a USB camera and a USB microphone process the data and send the result to an external ...
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__report_bad_irq not getting hit

I am stucked in one issue, in which i am getting __report_bad_irq callstack inconsistently. AFAIK, whenever we have 100000 unhandled interrupts this stack kicks in. Output from cat /proc/irq/128/...
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redhat 7.7 nohz_full dynamic tickless behaviour

I'm trying to set dynamic tickless behaviour on certain cores (cores 2 - 11), moving all timekeeping to the only unspecified cores (cores 0-1). However, when I perform the instructions specified in: ...
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317 views

Custom interrupt handler for the NMI hardware button

I'm trying to create a custom interrupt handler for the NMI hardware button which exists on my motherboard. To test this functionality I've created this simple module: #include <linux/init.h> #...
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Manjaro/Arch: Disabling IRQ #31 on Thinkpad X1 7th

I've stumbled upon the beforementioned error during boot and have tried to resolve it by trying to find out what caused the interrupt. Sadly, lspci -v | grep 31 gives no result and a cat /proc/...
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What are the non-numeric IRQs in /proc/interrupts?

cat /proc/interrupts shows a bunch of IRQs such as NMI and LOC. The per-line comments in the output give clear explanation, but if they do not have a numeric IRQ number, how does the x86 CPU respond ...
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No irq handler for vector when using hwinfo --short

I have been reading the various fora, while they seem to fix the annoying error, they don't tell the reason why the error crops in the first place. The error message I get - Message from syslogd@...
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running a terminal over PCMCIA serial port in unix

I'm currently doing a microcontroller project that requires a serial port, but for testing purposes, I require two serial ports and terminals working with both of them. My computer has one native ...
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How does Linux Kernel switches from kernel stack to interrupt stack?

What happens when a user mode task is interrupted ? I know for a fact that the CPU switches to the kernel mode stack by refring the TSS. But when and how does the kernel switches to the IRQ stack?
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How to keep Linux kworker threads alive?

I'm experiencing some data loss on a USB-to-serial adapter on a Raspberry Pi running at a (relatively) high data rate. I believe most of the work is carried out by kernel threads: 2569 root 20 ...
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1 answer
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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 ...
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3 answers
6k views

How linux know which irq number should be used?

I am not a driver programmer, I don't have a clear picture of how linux assign irq number for pcie devices. From an NIC driver example, it seems Linux already know which irq number should be used ...
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Very High CPU Usage By IRQ #16

I recently noticed that one of my CPUs was idling at around 85-90% and according to top the usage was coming from interrupts, so just like in this question I used a combination of dmesg and ...
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3 votes
1 answer
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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, ...
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6 votes
3 answers
15k views

How do I kill an IRQ process in Linux?

I can not kill irq/${nnn}-nvidia by kill -9 or pkill -f -9. Does anyone how to kill or stop those process? (I am using Ubuntu 16.04, if that is relevant.)
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What does this mean: "Interrupt: pin A routed to IRQ 17"

When I run the command: sudo lspci -vvv, I see the following among the output: 0c:00.0 Network controller: Broadcom Corporation BCM4311 802.11b/g WLAN (rev 01) Subsystem: Dell Wireless 1390 ...
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2 votes
1 answer
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do_IRQ: 0.163 No irq handler for vector (irq -1)

Why do I get this message in the terminal (putty) ? Message from syslogd@Debian-87-jessie-64-minimal at May 27 01:14:25 ... kernel:[ 8242.806151] do_IRQ: 0.163 No irq handler for vector (irq -1)
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4 votes
2 answers
1k views

Two interrupt handlers for the same driver

I have a scenario where my driver needs to listen to two different interrupts from two different IRQ lines. Is it possible to register two different IRQs and install two different handlers for the ...
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1 answer
434 views

AWS EC2 ethernet irq sharing issue

I have create m4.x2large instance with SR-IOV enabled and running some sipp performance testing and i have notice on top command ksoftirq/5 is 100% and it stick to CPU5 all other CPUs has 0% load, I ...
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14 votes
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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/...
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