Questions tagged [interrupts]

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High interrupt and context switch count on Nomad / Docker

We are seeing rather high interrupt and context switch counts on our Nomad clients: # vmstat 1 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free ...
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ksoftirqd maxing out for network interfaces

We have a Debian server with one link to the internal VLAN, and one to the external - both connect directly to the same switch. On both links, we're intermittently seeing an unusually high amount of ...
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Interrupt distribution on intel X710 NIC

I have a VPN server with Intel X710 and Xeon E5-2630 v4. Debian 10. Based on accel-ppp, pptp protocol. Single SFP interface, two vlans. Problem - interrupts are not evenly distributed across queues. ...
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2 votes
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Network discards on powerful Linux server

I got quite powerful Linux server - Dell PowerEdge R6515 it contains x64 cores using AMD Epyc cpu. Also there're dedicated LAN PCI: lspci | grep 10G 41:00.0 Ethernet controller: Intel Corporation ...
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2 votes
1 answer
440 views

Bad Linux storage performance, in comparison with Windows on the same machine

(the question was reformulated, I think it needed to be more structured) We have a Proxmox VE on Dell PowerEdge R610 gen 8 system. The platform is old, but we use it for particular S/W which is well ...
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3 votes
1 answer
2k views

Server suddenly has high softirq cpu use after reboot

A 48 GB RAM virtual server maintaining about 25k TCP connections (devices in the field logging in to set up an SSH tunnel) ran out of RAM and started swapping, and getting slow, etc. We upgraded and ...
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too many nic intterupts caused performance issue on haproxy server

i have a ubuntu 18.04.1 server running with 8-core processor and 8 Gigabyte's of memory. it's a cloud server which is based on KVM virtualization. i am using haproxy 1.8.8 for load balancing on my ...
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2 votes
0 answers
624 views

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 ...
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Distribute IRQs across multiple cores

I have a centos vm and I am trying to distribute the softirqs across multiple cores. I have modified the smp_affinity_list from 3 to 0-3 but instead of balancing the interrupts, it just moved the ...
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3 votes
0 answers
579 views

Areca Raid Controller "ARC-1883" fails when heavy network load

I have a "Areca ARC-1883IX-12" Raid Controller firmware 1.54 running OpenSuse 42.3 with XEN Hypervisor. I use four instances of a copy command to copy four big binary files within the local file ...
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1 vote
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Windows: high Interrupts and Context Switches rates

I'm experiencing very high rate of Interrupts/sec and CSwitch/sec on my Windows10 machine. I'd look to understand whether it's a normal situation or not. For me the rates are seemed to high. Please ...
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7 votes
1 answer
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What is this column in /proc/interrupts?

Can someone assist me in analyzing the data in this output from my /proc/interrupts file? $ cat /proc/interrupts CPU0 CPU1 0: 22 0 IR-IO-APIC 2-edge timer ...
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5 votes
1 answer
1k views

Do system calls in x86_64 linux still generate interrupts?

In older versions of linux architecture, system calls would always generate an interrupt during their execution. They would be executed by setting the system call number into %eax and parameters into %...
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How much interrupts is too much?

On an AWS instance x1.32xlarge (128 cores), we are getting a lot of interrupts per seconds. Here are the top CPUs in interrupts/s: Interrupts Top CPUs CPU0: 140838.0 CPU1: 77867.0 CPU4: 66495.0 CPU6:...
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2 votes
1 answer
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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 ...
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6 votes
2 answers
8k views

High system interrupt rate

My server has 24 CPU cores, 96G memory, installed CentOS 7.2 x86_64. After starting my program with a large data set, my program will use about 50G memory, and the Linux system will show a high rate ...
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3 votes
0 answers
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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 ...
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1 vote
0 answers
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High TLB Shootdown Counts are Affecting Performance

We are running an app in JBoss EAP on RHEL 6.7 and are experiencing significantly different performance across the cluster. Of the 8 VMs, most will respond to requests in ~200ms but one or two will ...
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7 votes
3 answers
25k views

how to tell if NIC has multiqueue enabled?

Can anyone tell me what command i run to determine if my 10G NIC is running in single RX-TX queue mode or multiqueue? It looks like it only has 1 RX/TX queue according to cat /proc/interrupts root@...
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does an OS interrupt check for permissions

I'm not sure if I'm at the right place to ask this but I'm learning about operating systems and I can't find any info on this. I read that interrupts are created when a call is made in user mode that ...
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2 votes
1 answer
2k views

Does disabling VT-d and interrupt remapping break MSI-X?

So I have a Dell PowerEdge R610 server running Debian Jessie which according to some docs has a faulty chipset: https://www.novell.com/support/kb/doc.php?id=7014344 (Intel 5500 rev 13). The provided ...
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1 vote
1 answer
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Setting affinity for network interrupts in Windows Server 2012 R2

We have an application that sends and receives a lot of network traffic - but interrupts are causing us to get lower than max performance. At 20 Mbps input and 20 Mbps output (on a 1 Gbps line), the ...
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1 vote
0 answers
2k views

High CPU caused by system interrupts

We have a three day old Idacentre A740 AIO PC. (windows 8.1 pro) The system is up-to-date. After we start the PC and "do notthing" the system interrupts taken 40% CPU time approximately. Tried to ...
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Enabled Intel® I/O Acceleration but no bytes transffered

I enabled IOAT but it seems that no data is transferred using DMA for network: I enabled IOAT in bios. CPU is Intel(R) Xeon(R) CPU E5-2650 v2 @ 2.60GHz. I loaded the module in ubuntu 14.04 (3.11.0-26-...
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2 votes
1 answer
610 views

Interrupts are confined to only CPU0 Core why?

Why interrupts are confined to CPU0, rather than using other cores that are available? Only for LOC: I could see the interrupts being distributed to other cores why it's not happening for eth0 and ...
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0 votes
1 answer
543 views

Events/1 and Server Interrupts

Currently I am seeing a lot of CPU usage on events/1 and I was wanting to know how to figure out what is causing that? cat /proc/interrupts CPU0 CPU1 CPU2 CPU3 ...
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Tracing down High Linux Load - HDD at fault or too many interrupts ? (ksoftirqd Time 437:44.13)

Server Stats: "cat /proc/version" Output Linux version 2.6.18-308.24.1.el5 (mockbuild@builder17.centos.org) (gcc version 4.1.2 20080704 (Red Hat 4.1.2-52)) #1 SMP Tue Dec 4 17:43:34 EST 2012 ...
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2 votes
1 answer
1k views

Can't update smp_affinity

As part of the experiments that we are running to optimize the performance of the applications on our Linux box we are trying to assign all the network interrupts to a single cpu core. Unfortunately, ...
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5 votes
1 answer
4k views

How does a NIC send a hardware interrupt? [closed]

Some context. A few weeks ago, a NIC was replaced on a box without much troubleshooting to find a clear resolution to the problem. A senior administrator got into a small tiff with an entry-level ...
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2 votes
0 answers
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High Interrupts and DPC in Windows after reboot

We have seen this several times in Win 2003 R2 32bit, XenApp 4.5 server where we have to reboot them to get rid of the problem. Sometimes more than once. We've had this issue on both smaller virtual ...
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12 votes
3 answers
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CPU0 is swamped with eth1 interrupts

I've got an Ubuntu VM, running inside Ubuntu-based Xen XCP. It hosts a custom FCGI-based HTTP service, behind nginx. Under load from ab the first CPU core is saturated, and the rest is under-loaded. ...
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2 votes
0 answers
727 views

Disabling IRQ#16 when removing DVI cable [closed]

I have a computer running with a Blackmagic Decklink card and a usbscreen. The problem i'm having is somethimes a irq conflict occurs and the OS disables irq16 witch both the decklink card and the usb ...
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3 votes
1 answer
991 views

Linux Kernel IRQ Routing with irqbalance / kernel options

I'm trying to get my Xen Dom0 distributing the irqs in an smp enviroment. As far as I know there are 2 Options: Use irqbalance Configure the kernel without cpu hotplug support My System is Debian ...
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4 votes
1 answer
4k views

Software Interrupts CPU time is high and keeps growing

My system is a Debian 6.0.3 x86_64 box w/kernel 2.6.32-5-openvz-amd64, it hosts a number of OpenVZ containers. I have recently migrated from LXC/newer kernel from backports repo to the stable OpenVZ ...
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-1 votes
2 answers
494 views

Can it be because of any Kernel Bugs?specifically spin lock

We are running ubuntu 11.04 with 2.6.38-13-generic kernel on Intel(R) Xeon(R) CPU E5620 @ 2.40GHz with 48 GB RAM dedicated server with Hardware RAID. top command output is showing many kernel ...
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-3 votes
1 answer
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Can a large number of network hardware interrupts cause a machine to be underutilized?

I don't know much about networking sorry. I'm building a client / server where the server streams a lot of data to the client and I'm trying to maximise throughput (through TCP). If I run both client ...
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9 votes
4 answers
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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 ...
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6 votes
2 answers
562 views

CPU load inhibits interrupts on Linux

I have an Ubuntu box with 3.2 kernel, CPU with 2 cores and CAN (Controller Area Network) card based on SJA1000 controller attached via PCI bus. I'm testing receive capabilities of the card. It can ...
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3 votes
3 answers
6k views

Linux Interrupts Issue

Is there a simple way to determine if interrupts are a performance issue? I have the following from cat /proc/interrupts but really don't have a history of this server so I don't know if this could ...
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2 votes
1 answer
861 views

High interrupts, sometimes freezes

We have a Win 2003 R2 TS (x86) which has some "bad days". I have not been collecting data on this myself until just now, but it seems most of the time it runs fine, but some days we see high CPU usage,...
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1 vote
1 answer
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What's the difference between hardware and software interrupt? [closed]

I'm gonna sketch my understanding of both. I've googled around but i'm not sure about my knowledge. Please correct me! Hardware interrupt is generated by the operation system event scheduler to ...
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1 answer
373 views

Irregular interrupts balance in AMD Opetron Quad-Core

I had a problem with CPU7 overload. I found that it was caused by the eth0 interrupts, as you can see on below cat /proc/interrupts. I'm using 2.6.35.2 kernel and Quad-Core AMD Opteron(tm) Processor ...
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5 votes
1 answer
823 views

BSD 50% interrupt utilization in irq0/clock

On OpenBSD on an Atom 450, with HPET configured in the BIOS and not, also with Hyperthreading/ACPI on-off, nothing seems to make a difference. Here's my vmstat -iz # vmstat 2 procs memory ...
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5 votes
3 answers
5k views

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 ...
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2 votes
1 answer
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Distribute IP packets accross different NIC queues with MSI (Message Signalled Interrupts)

NetXtreme II BCM5709 Gigabit Ethernet NIC supports MSI feature (Message Signaled Interrupts) and it has 8 queues. Each queue has its own Interrupt handler in /proc/interrupts. What I am trying to ...
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48 votes
4 answers
70k views

How can I find out what is causing interrupts on Windows?

Occasionally I come across servers (Windows 2003 and 2008) with high processor % interrupt time. Is there a way to see what program or device is causing the interrupts?
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What are RES interrupts (from Munin)

Our server recently had a very bad day, and one of the indicators/reasons seems to be that RES interrupts are douple their normal value, but what does this mean ? (other interrupts: LOC+100%, eth1/...
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2 answers
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kernel software trap handling

I'm reading a book on Windows Internals and there's something I don't understand: "The kernel handles software interrupts either as part of hardware interrupt handling or synchronously when a thread ...
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22 votes
1 answer
28k views

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 ...
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2 answers
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Alternative to /proc/interrupts

I would like to obtain information about interrupts assigned to my network cards. Is there any other way, than /proc/interrupts?
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