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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11 views

How to run a function for every specific received packet? [on hold]

I am doing an experiment for my master thesis. I want to run a function (e.g. multiply two numbers) when a specific packet is received (e.g. a packet with destination TCP port 6666). For example, I ...
0
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1answer
1k views

Compiling an individual kernel module (Debian/Ubuntu)

I need to modify the ELF loader's kernel implementation of an Ubuntu 14.04 distribution. Having downloaded the sources using: sudo apt-get source linux-image-$(uname -r) I ran the configuration ...
1
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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. ...
2
votes
2answers
2k views

grubby fatal error: unable to find a suitable template

I'm trying to fix my system after moving it from one server to another. It works perfectly with kernel booted via network, but not from the disk. Reinstalling stock CentOS 6.6 kernel shows this error:...
0
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1answer
17 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 ...
0
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0answers
27 views

Server hangs with the following messages and on reboot starts to check file system automatically?

these were the messages on the system when i took the drac die+8be/8x98 dOithp+8XC4/8X168 dOidiUidEiEPPOP+8X8f/8Xb8 findibusiestigroup+8xSC5/8Xb28 tcpiestablishediopti0n$+8X43/8Xd8 thiCUPPEDtimSS+...
0
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1answer
47 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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0answers
36 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 ...
0
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1answer
64 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 ...
0
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0answers
375 views

Debian Jessie 8 idle on fresh install always a little too high, shows rcu_sched ksoftirqd kworker causing cpu load

Are the days of 0.0 cpu load on an "idle" server gone? I have another server (centos/redhat) 32GB ram that actually runs apache/MySQL/Lamp, mono, redmine/ruby, and other junk and its still shows me 0....
0
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0answers
3 views

Update kernel on arm device [migrated]

How can I update the kernel of my ARM device? The device I have been using is A20-Olinuxino LIME board, with Debian GNU/Linux 7.6 (wheezy) image booted from NAND. The uname -a command displayes 3.4....
0
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0answers
44 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 ...
2
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2answers
3k views

CentOS 6 Xen guest fails to boot after 'yum update'. Kernel?

I Seem to be having an issue with a Xen guest not booting after a yum update. DomU Configuration: #kernel = '/boot/solus-vmlinuz' #ramdisk = '/boot/solus-initrd.img' bootloader = '/usr/bin/...
0
votes
0answers
5 views

Push firmware files in ath10k to Debian firmware-atheros [migrated]

I would like to quote wireless.wiki.kernel.org: The ath10k firmware images are available from linux-firmware.git which all common Linux distributions should install by default. Latest firmware ...
0
votes
1answer
2k views

Kernel: dst cache overflow

I'm under continuous floods at time that are generally of lower magnitudes. I've observed my system often to become totally unresponsive on its network while I observed this in the logs, kernel: [...
3
votes
1answer
2k views

What does nf_conntrack.acct really do?

I've found the kernel parameter nf_conntrack.acct interesting, in that the kernel documentation merely says "Enable connection tracking flow accounting". I've appended this to grub and rebooted and I ...
0
votes
1answer
29 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 ...
72
votes
23answers
27k views

rm on a directory with millions of files

Background: physical server, about two years old, 7200-RPM SATA drives connected to a 3Ware RAID card, ext3 FS mounted noatime and data=ordered, not under crazy load, kernel 2.6.18-92.1.22.el5, uptime ...
9
votes
1answer
509 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 ...
0
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0answers
44 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 ...
6
votes
1answer
13k views

Will increasing net.core.somaxconn make a difference?

I got into an argument on the net.core.somaxconn parameter: I was told that it will not make any difference if we change the default 128. I believed this might be enough proof: "If the backlog ...
1
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0answers
70 views

Kernel fails to assign memory in any Linux Distro

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
18 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 ...
0
votes
2answers
97 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@...
34
votes
2answers
20k views

Damaged /vmlinuz and /initrd.img symbolic links after Kernel uninstall

OS: Ubuntu 8.04 LTS Server Edition We just rolled back an kernel update using the following command: sudo apt-get remove linux-image-2.6.24-24-server The uninstallation was successful, but it had ...
0
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0answers
20 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
87 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 ...
3
votes
1answer
1k views

Linode Kernel Headers

I am trying to install the Idera (R1soft) linux agent on a Linode running Ubuntu 12.04LTS. The agent requires a driver which in turn requires the kernel headers. Linode uses custom kernels though so ...
2
votes
0answers
53 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
68 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 ...
4
votes
2answers
2k views

TIME_WAIT consumes file descriptors?

In many TCPIP and Web tunning guide, recommends increasing max number of file descriptors when getting the error "Too many open files" but, i can't see TIME_WAIT in outputs of "lsof -i" Does anyone ...
0
votes
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 ...
1
vote
0answers
578 views

Xen hangs on boot when scrubbing RAM

I have a CentOS 5 server I can boot into the stock kernel just fine, but when I try kernel-xen, it gets stuck here: When I try adding no-bootscrub to the kernel command line, I get this and a ...
1
vote
1answer
745 views

CentOS OpenVZ fail to boot after kernel update

After upgrading to latest OpenVZ kernel CentOS server won't boot. When i try go boot the latest kernel server is stuck at this point: (note that images are taken from virtual kvm) Then i try to ...
3
votes
1answer
2k views

Build kernel headers to compile R1Soft hcp module

I'm running a Xen based VM with CentOS 5, and my hosting provider pushes kernel version 2.6.37.6 from the host machine (so no pv-grub). [root@dev ~]# uname -r 2.6.37.6 I'm trying to install the ...
16
votes
4answers
20k 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?
0
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0answers
35 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 [...
1
vote
1answer
3k views

Unable to mount fat drive in linux

This is sort of a continuation from How to mount a .bin image file in linux but it morphed into a different problem altogether, so I figured I'd ask a new question with the relevant info rather than ...
0
votes
2answers
1k views

yum install kernel source

I'm installing dahdi on my Fedora 15 machine and when I try to build, I receive the following error You do not appear to have the sources for the 2.6.38.6-27.fc15.x86_64 kernel installed. The ...
7
votes
3answers
42k views

can high load cause server hang and error “blocked for more than 120 seconds”?

Currently running a few VM's and 'baremetal' servers. Java is running on high - over 400%+ at times. Randomly the server hangs with the error in the console "java - blocked for more than 120 seconds" -...
28
votes
6answers
76k views

Improving TCP performance over a gigabit network with lots of connections and high traffic of small packets

I’m trying to improve my TCP throughput over a “gigabit network with lots of connections and high traffic of small packets”. My server OS is Ubuntu 11.10 Server 64bit. There are about 50.000 (and ...
5
votes
1answer
349 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 ...
5
votes
3answers
362 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 ...
3
votes
1answer
190 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 ...
1
vote
1answer
24 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 &...
0
votes
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 ...
5
votes
1answer
2k views

Some questions about kernel.random.* parameters

I'm trying to understand the linux kernel parameters which are under /proc/sys/kernel/random/, but I have some troubles. Could you help me figure some things out? What is the boot_id parameter used ...
0
votes
1answer
676 views

/proc/self/mountinfo per-mount-options vs per-super-options

I am trying to check for the current status of a mounted partition, rw/ro. On Cent6 /proc/self/mountinfo has some interesting info. One of the items contained in the output for each mount point is "...
1
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1answer
69 views

How to disable ip_forward for Ubuntu server

This is the state of my server right after booting: root@vzu01-ubuntu:~# cat /proc/sys/net/ipv4/ip_forward 1 There is no other enabled ip_forward configuration: root@vzu01-ubuntu:~# grep -r ...
8
votes
2answers
9k views

Can I increase inode count in Linux?

I have a Linux MIPS router with 2.4.17 kernel. Root fs is a tmpfs and /rom is a cramfs. There is 4MB free memory and 3MB free on tmpfs. I can create a few new empty files, but the next ones fail ...