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Questions tagged [irq]

42 questions
22
votes
1 answer

What's the cause of high LOC interrupts?

I'm seeing huge spikes in LOC interrupts - around 4 million per second, what exactly is the LOC interrupt, what would cause these spikes, and what can I do about it? Here's a Munin graph illustrating these spikes:                      Here's the CPU…
Paul Dixon
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12
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2 answers

10/20/40Gbps nginx large files caching webserver [20Gbps reached]

I would like to find out the best possible configuration/hardware to deliver 40Gbps from a single server in this question. Situation We have a video share proxy server that offloads peaks from slow storage servers behind it. All traffic is HTTP…
Yarik Dot
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9
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4 answers

How to ban hardware interrupts with IRQBALANCE_BANNED_CPUS on Ubuntu?

I would like to ban interrupts from certain CPUs. I heard about the IRQBALANCE_BANNED_CPUS option. I see irqbalance is running in the background of my machine. Where do I go to edit and how do I configure that option? For example, I want to exclude…
TraderJoeChicago
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5
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3 answers

ethernet smp_affinity vs /proc/interrupts vs /sys/class/net/ethX/device

My goal is to configure our CentOS ("free" RHEL) 5.x servers for custom low-latency network programs. I would like to experiment with binding ethernet NIC interrupt handling to the same CPU on which the program runs (to hopefully improve cache…
Matt
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4
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1 answer

IRQ Interrupts ESXi

We are trying to determine the pros and cons of allotting different number of CPUs to VMs (VMware). We would like to see how the VMware kernel is dividing up the total number of cores/threads and determine the best architecture for our specific…
JMeterX
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4
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3 answers

SATA drive problems with two SIL RAID cards

I've just put a second SiI 3114 SATARaid card in my home server so that I could add another pair of SATA drives and increase my storage space. Annoyingly, it doesn't seem to work: [ 32.816030] ata5: lost interrupt (Status 0x0) [ 32.816072]…
Jon Topper
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3 answers

How can I override IRQ affinity for NVME devices

I am trying to move all interrupts over to cores 0-3 to keep the rest of my cores free for high speed, low latency virtualization. I wrote a quick script to set IRQ affinity to 0-3: #!/bin/bash while IFS= read -r LINE; do echo "0-3 ->…
Hubro
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3
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Cannot balance eth0 IRQs across CPUs

I have servers which deal with a large number of network packets. I've seen evidence that user space processes running on CPU0 have their performance impacted when network load is high. I'm fairly sure this relates to interrupt handling,…
Andrew Parker
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High network softirq requests for kernel 3.10 under a lot of traffic

We have been experimenting rolling out 3.10 series kernel that's provided by centos via the centosplus repo for v6. We have been noticing something interesting where under the same load the load for the server is 6-7x more on the 3.10 series then…
Mike
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How to change SMP affinity of an IRQ on Ubuntu PV domU inside Xen XCP?

I'd like to change IRQ SMP affinity for reasons, outlined in this question: CPU0 is swamped with eth1 interrupts But I can't — I see Input/output error when I try to write to /proc/irq/*/smp_affinity. Please point me to the HOWTO on the matter. (A…
Alexander Gladysh
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3 answers

Logging Hardware Interrupts (IRQs) which are using 10-25% CPU

I have a server using 10-25% of the CPU time on Hardware Interrupts according to Process Explorer. How would I go about logging/diagnosing the cause of all these IRQ calls? The machine is virtual, so I know the physical hardware is not the problem…
Garrett
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QEMU-KVM bug: guest interface locks up a core with soft interrupts

Bug: I have a qemu-kvm on Ubuntu (host 14.04.5 LTS 3.13.0-95; cannot upgrade; , guest Ubuntu 18.04.03 LTS 4.15.0-65) Guest has two network interfaces, directly (VEPA) connected to two separate host physical interfaces. A program running on guest…
Alec Matusis
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1 answer

ksoftirqd and events process high CPU load

Centos 6.9 (64gb Ram) Running nginx, mariadb, php-fpm, iptables, java The server is having random but frequent bursts of 100% system cpu load on only 1 core, crippling network connections to the server. I found out that even with nginx, mariadb,…
SensitiveGuy
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1 answer

How irqbalance works

Does irqbalance add kernel module? How a user space daemon is able to assign interrupts to different processors? If it is a user space process that is doing it, won't kernel to user space context switch delay the interrupt processing?
kalyan
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3 answers

cause for high Interrupts and context switches

I have a quad core and I have spotted on munin (monitoring interrupts and context switches), that my interrupts and context switches spiked to 25k a second while the average was 250 for some time. No idea what happened, and also no idea what does it…
Adam Benayoun
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