In computing, the kernel is the main component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level. The kernel's responsibilities include managing the system's resources (the communication between hardware and software ...

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16 views

Task Manager shows high kernel time

Foreward: Hardware: dual-socket Intel Xeon, 128gb memory, hardware RAID-1 SSD OS: Windows 2012 R2 Standard w/ Remote Desktop Services The Task Manager for one of our terminal/application servers ...
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2answers
33 views

Linux + how to clean /boot and stay only with the current kernel version files

Under /boot we have the following files ( red-hat Linux version 6.6 ) cd /boot # ls -ltr drwx------ 2 root root 12288 Oct 15 2015 lost+found -rwxr-xr-x 1 root root 4152624 Oct 15 2015 ...
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1answer
29 views

How to upgrade Linux Kernel (Linux vps180 2.6.32-37-pve #1 SMP Wed Mar 18 08:19:56 CET 2015 i686 GNU/Linux)

Good Day! Im having a difficulties in upgrading this server's kernel. Since I am new to this server management. Anyone who have idea to upgrade this type of server ? Linux vps180 2.6.32-37-pve #1 ...
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1answer
17 views

Is it ok to remove kernel-debug* on a production system if it's preventing upgrades? KVM template: /boot does not have enough space

So there are legacy CentOS 6.x VPS templates on a very good host which are "stuck" with a 100mb /boot partition. Unfortunately since it was spawned ~4 years ago, one of our servers falls into this ...
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2answers
101 views

how to configure the grub.cfg file on redhat 7 in order to boot from specific kernel

In Red Hat EL versions 5 and 6 we can easily to update the /etc/grub.conf in case we want to change the kernel by default variable For example , grub.conf on redhat 5 default=0 timeout=5 #...
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0answers
33 views

kernel module loaded and activated itself

My daily tripwire scan on my VPS has shown new files added in /proc/sys/net/dccp, and in the kernel logs it has indeed been activated. Is it normal for a kernel module to randomly activate itself? I ...
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1answer
73 views

Kernel panic - not syncing: Attempted to kill init ( using qemu for a Rasbian ARM image) [closed]

I am using qemu 2.6.0 on my ubuntu 14.04 x86_64 PC. I want to emulate rasbian -- A Linux destro based on ARM Debian for Raspberry Pi. Here's the settings when using qemu /usr/local/src/qemu-2.6.0/...
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0answers
10 views

Why does reading /proc/net/tcp take a long time ss is quick to return the same sort of data about the connections table? [migrated]

On Linux 2.6.32, if you read (for example, cat) /proc/net/tcp, on a very loaded system (for example, a web server), you will find that reading 100K entries takes over 30 seconds. That's a long time. ...
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1answer
20 views

Unable to find file system erro in Debian Live CD over PXE

I'm having trouble setting up a Debian Live CD to run over HTTP with PXE. I can not see the problem, apache logs indicate 200 to request that accesses the filesystem.squashfs. The console looks like ...
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1answer
53 views

linux + dose each security kernel rpm will install the relevant initrd and vmlinuz files under /boot

I just print the kernel rpms that need to install on my redhat machine (version 6.5) # yum list-security --security | grep kernel-[0-9] RHSA-2014:1143 security kernel-2.6.18-371.12.1.el5.x86_64 ...
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1answer
73 views

linux redhat + how to install only the latest kernel rpm under /boot

installing of errata security kernel rpm ( from redhat sattelite ) on the linux red-hat, could sometimes - create a diff 2-4 new update kernel under /boot , the problem here that /boot could be ...
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0answers
53 views

CentOS: / (root) partition reached 90%

We are facing an issue in our production system, running on Cent OS 7. The / (root) partition reached 90% of disk space but we don’t have any huge files / hidden files on that machine. Kindly help us ...
9
votes
1answer
533 views

How does CPU affinity interact with cgroups in Linux?

I'm trying to run multi-threaded benchmarks on a set of isolated CPUs. To cut a long story short, I initially tried with isolcpus and taskset, but hit problems. Now I'm playing with cgroups/csets. I ...
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0answers
48 views

Kernel panic on Dell R710 Kernel 4.4.1

We are running Debian 7.9 server with kernel 4.4.1 on Dell R710 (Intel(R) Xeon(R) CPU X5670 @ 2.93GHz) and after some time (maybe once a month) server stop working and I see on a screen the kernel ...
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0answers
110 views

Kernel fails to assign memory in any Linux Distro [on hold]

I have a motherboard: X11SBA-LN4F/F. After install CentOS, i have error in log: May 2 21:47:48 ll-226 kernel: pci 0000:04:04.0: BAR 14: failed to assign [mem size 0x00200000] May 2 21:47:48 ll-226 ...
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0answers
23 views

BSOD BugCheck on Multi-core system - What thread caused the crash?

I am aware that a Windows' system will crash with a stop error and "blue screen" for a few common reasons, some of which may be: A device driver or OS function that runs in kernel-mode space ...
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2answers
134 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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0answers
21 views

Having trouble figureing out how copy_from_user works

I'm currently trying to create a system call in C for a custom linux kernel. I'm using the copy_from_user to copy user level data to a local kernel variable, but I always seem to getting the EFAULT ...
1
vote
1answer
114 views

nvme device dropouts - I/O 0 QID 0 timeout, controller disabled

We have 6 Supermicro servers all of the same (or very similar spec), Over the last two weeks one of them has been dropped an NVMe disk at random times due to: [ 66.856719] nvme 0000:03:00.0: I/O 0 ...
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votes
1answer
32 views

Kernel errors with 3.13.0-71-generic

After upgrading several hosts to Ubuntu 12.04.5 LTS with the LTS enablement stack (linux-generic-lts-trusty 3.13.0.40.35), we are seeing a sudden spike in kernel errors. These only begin to occur ...
2
votes
0answers
64 views

how to read the results about packet drops from crash tool

I have Linux machine red hat 7.2 because the dropping problem on eth1 interface we perform the test according to red hat link - https://access.redhat.com/solutions/206223 finally we get the ...
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votes
1answer
128 views

How to know if the reboot cause is a linux kernel crash? [closed]

When my system reboot. I want to know the cause of the reboot especially when the reboot cause is a kernel crash. Are there a way to know if the reboot cause is linux kernel crash? like read ...
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0answers
10 views

Is it possible to run CMAN without configfs?

I run a custom 3.18.x kernel that does not have configfs enabled. Is it possible to run CMAN cluster management without configfs? If necessary it would be much easier for me to rebuild CMAN than it ...
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0answers
41 views

Log file bloat due to nouveau

Both my kern.log and syslog files have grown to >50Gb and contain a few hundred million lines of: Feb 23 23:32:43 Yawning-Angel kernel: [396111.179453] nouveau E[ PFIFO][0000:05:00.0] PBDMA0: ch 2 [...
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votes
3answers
469 views

How to fine tune TCP performance on Linux with a 10Gb fiber connection

We have 2 Red Hat servers that are dedicated for customer speedtest. They both use 10Gb fiber connections and sit on 10Gb links. All network gear in between these servers fully support 10Gb/s. Using ...
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2answers
31 views

Why takes CLEARING swap soo long?

Why is moving from RAM to swap fast and from swap to RAM very slow? When I run program that needs more memory that is available, I see that the RAM is prety quickly "cleaned" by moving unsused (=the ...
3
votes
1answer
209 views

High load average, but low CPU/IO figures - how to diagnose? (dmesg output included)

We have a Hadoop cluster where arbitrary data nodes will lock up. This is usually pre-ceded by ever-increasing load averages, with CPU and IOwait remaining practically non-existant. The use case for ...
6
votes
1answer
415 views

systemd Using 4GB RAM After 18 Days of Uptime

I have a web server running CentOS 7, on which the systemd process is using nearly 4 GB of RAM after a couple weeks of uptime. RAM usage is increasing steadily at about 200MB per day. This and related ...
1
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1answer
25 views

What happens when I press Ctrl+C when e2fsck running?

What happens when I press Ctrl+C when e2fsck running ? will it go to command prompt ? or it will reboot & then the server again goes to fsck ? Reason Why I want ? I want the server to up &...
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0answers
160 views

Got kernel panic with 3w-sas driver after kernel update

I use CentOS 6.7 and I've got kernel panic related to LSI 3ware 9750-4i Controller after kernel update from 2.6.32-431.17.1.el6.x86_64 to 2.6.32-573.12.1.el6.x86_64. It is minor update, so I think it ...
2
votes
0answers
42 views

How to reliably capture Linux kernel log messages in case of a system debilitating crash (BUG, panic)?

I'd like to have access to the lines/tracebacks/whatever whispered by the kernel right before dying. This has proven problematic, because all interfaces I have access to become disabled. Post-reboot, ...
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0answers
69 views

EFI shell boot vmlinuz : no filesystem could mount root, tried :

I am trying to boot an installed OS from UEFI shell. This machine doesn't have a legacy boot. Only option is to use EFI shell. I am using a custom compiled kernel-3.18.17. I could load vmlinuz, but ...
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2answers
88 views

Mysql locks up linux server during high load

Every day during the generation of some reports the mysql process takes up 1 or 2 cores (100%). The problem is that the whole server becomes unresponsive during that time. I can't ssh, postfix doesn't ...
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0answers
39 views

X9SRL-F Crashing Ubuntu

We are running a KVM server node on Ubuntu 14.04.3 LTS with some VMs for a while now. About 3 months ago we noticed a random crash at night without any crashdata, the system seemed to be frozen back ...
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0answers
25 views

How can I track security issues with running kernel under paravirtualisation?

I've got a bunch of client's virtual machines running by various providers who use Xen paravirtualisation. Almost all of these are Debian or Debian based systems. I rely on APT pretty heavily to ...
4
votes
0answers
48 views

What are sensible semaphore numbers?

What are semaphores and how are they caused? has a fairly good explanation of what semaphores are, but I'm not sure what my configuration should be. I recently ran into the same problem as that ...
0
votes
1answer
109 views

How to edit /proc/partitions file in linux

I know /proc is a VFS and cannot be updated by user from shell prompt. this is my understanding from the beginning. Now , I am writing one code and where I am taking care of corrupted /proc/partitions ...
4
votes
1answer
2k views

Why are connections in FIN_WAIT2 state not closed by the Linux kernel?

I have an issue in a long-lived process called kube-proxy being part of Kubernetes. The problem is that from time to time a connection is left in FIN_WAIT2 state. $ sudo netstat -tpn | grep ...
0
votes
2answers
31 views

How to unlist partitions from fdisk command in linux

While working on one of my server I noticed that there are no partitions listed under "fdisk -l" command. However the machine is working just fine. Wanted to know following things if anyone can help. ...
0
votes
1answer
59 views

How to get notified when a server started with gcloud is completely up

Is there a way to detect when a server is completely up (i.e. finished all the kernel startup tasks)? This is a Google Compute Engine Instance. Nov 18 10:58:51 image-name google: No startup script ...
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0answers
29 views

Weird network interrupt issue

in ifconfig output i am seeing Interrupt 16 but when i check in /proc/irq/ i am not seeing number 16 there. following number i am seeing here. my driver is broadcom tg3 [root@centos7 ~]# ls /proc/...
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vote
1answer
40 views

Postgresql calculate kernel share memory?

We are running PGSQL 9.2 and following are hardware specs OS: CentOS7 64bit CPU: 24 Memory: 32GB Disk: SSD I want to calculate shmmax/shmall values then what would be the good way? I google it and ...
2
votes
1answer
200 views

NVMe speed degradation after kernel upgrade

We are testing the speed of two Intel DC P3600 NVMe drives on a CentOS 7.1 system. They are configured in a software RAID1 using mdadm. After upgrading the kernel from the (very old) 3.10 to the ...
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0answers
41 views

Kernel config options explained

Can anyone explain what the following options from my centos 5.9 box do CONFIG_HAS_IOPORT=y CONFIG_HAS_DMA=y CONFIG_GENERIC_HARDIRQS=y CONFIG_GENERIC_IRQ_PROBE=y CONFIG_GENERIC_PENDING_IRQ=y ...
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1answer
202 views

PXE boot kernel panic

I am having trouble setting up a PXE boot server. I've got isc-dhcp-server running, tftp-hpa serves the files over tftp (verified works), and apache2 hosts the rootfs image. The PXE client seems to ...
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0answers
63 views

VIA south bridge puts CPU to sleep, disables timer and ethernet interrupts

I have two VIA NAB-7410 boards with 4x Intel 82541GI gigabit adapters. On both boards, Linux occasionally stops responding to Ethernet frames. The problem goes away when another interrupt is triggered,...
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0answers
32 views

Network issues or tcp stack load

I am running a NoSQL (aerospike) cluster on a set of identical hosts (ec2). Once in a while one of them would start timing out on queries and connections, and pings to it would go from < 1ms to 20-...
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0answers
223 views

Ubuntu server 14.04 postgres Tainted

I run an Ubuntu 14.04 server, on which Postgresql 9.3 is installed. I am seeing kernel messages flooding kern.log and syslog, hundreds of lines a minute, until the server is out of free space. I'm at ...
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0answers
474 views

centos 7: sysctl -p /etc/sysctl.d/50-default.conf returns error

I have rented container from OVH a while ago but last night all of a sudden my machine stopped responding on IP level... after reboot I have noticed the following systemd-sysctl.service - Apply ...
4
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3answers
199 views

How to prevent Alice to kill a process, but allow Bob to uninstall it?

I know Bob who is a system admin. Bob needs to deploy software Foo to Alice's work device based on Windows NT (XP onwards). Foo is security software. It is not malicious. Alice has local admin ...