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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19
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6answers
17k views

How do I list loaded Linux module parameter values?

Is there a standard way to list the parameter values of a loaded Linux module? I'm essentially probing for another answer to this Linux kernel module parameters question, because the module I'm ...
1
vote
1answer
25 views

CentOS 6.5 new Kernel not active after reboot

Today I was running some yum updates and wanted to verify that everything went through fine by making sure I had a new kernel. To my surprise I noticed that CentOS was still running ...
6
votes
0answers
145 views

Linux kernel 3.10.0-123.4.2 processes [flush] aren't present [migrated]

I am using CentOS 7 with "3.10.0-123.4.2.el7.x86_64" version, but I don't know why the kernel threads named flush aren't present in this kernel version. I tried to look in the kernel change log, but ...
5
votes
4answers
5k 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?
8
votes
1answer
226 views

TCP packet being retransmitted 7 times when sysctl tcp_retries1 is set to 3 - why?

Ubuntu 12.04 I am trying to better understand how many times TCP will attempt to retransmit a packet when it does not receive confirmation the destination received it. After reading the tcp man page ...
1
vote
2answers
22 views

How to check if Ubuntu 14.04 Kernel has TPROXY

I'm using Digital Ocean's Ubuntu 14.04 image and needs the kernel to be compiled for TPROXY. Is there a way to check whether the current kernel supports TPROXY?
-3
votes
1answer
26 views

Running Kernel 3.x in CentOS 6.x [duplicate]

I read that using the 3.x branch in CentOS 6 is a bad idea. Is there any reason as to why I should stick to the 2.6 branch? I've played around and have ran 3.x from compile with no problems under ...
1
vote
2answers
44 views

CentOS 6 - Kernel 3 from CentOS 7 Repo?

i want to run kernel 3 on centos 6. I found out, that it cant get installed over yum and i would need to compile it by my own. My question: Could i use the centos 7 repo to install kernel 3.x from ...
0
votes
2answers
773 views

systemtap not initializing correctly on Ubuntu 12 (Precise)

I work at a firm with a certain amount of legacy batch-processes. Some of that stuff is really leaky when it comes to database connections. I need to log every process in the system, which opens a ...
1
vote
2answers
23 views

When a socket switch to TIME_WAIT state, why I can't see its inode number?

I'm developing a program in python that parses /proc/net/tcp informations, but unfortunately, while I was doing this, I saw a strange thing. Practically, when a socket change in TIME_WAIT state, ...
-1
votes
1answer
24 views

Can you use CGroups inside an OpenVZ Container?

just a quick question, which i have had trouble finding the answer to: The OpenVZ Authors have been contributing a large amount of code to the linux kernel, in order to get virtualization features ...
0
votes
0answers
30 views

Nodes crash with kernel panic due to some bugs in autofs4 module

Recently, my computing nodes started to crash very often. In a pool of ~100 nodes running Ubuntu 12.04 for scientific computing, a machine dies every hour with the following kernel panic message: ...
0
votes
1answer
726 views

Kernel parameters mem and dom0_mem in XenServer 6.1

We are running XenServer 6.1 in production, and recently had OOM-killer fire and eventually take down one of our blades. I noticed that in the kernel logs from the oom-killer instance that it seemed ...
0
votes
1answer
120 views

GRUB “Some modules may be missing from core image” Error

one HDD crashed from my RAID and I added a new HDD. Now I wanted to install GRUB to the new HDD: with "grub-install /dev/sdb" I get these errors: Installing for i386-pc platform. grub-install: ...
0
votes
1answer
961 views

drivers/rtc/hctosys.c: unable to open rtc device (rtc0) after recompile on boot

After recompiling a new kernel on CentOS 6.3, using the same kernel I have been using on several other machines, I am getting a kernel panic on two machines. I get the following when trying to boot: ...
0
votes
1answer
3k views

Fatal: module iscsi_trgt not found — trying to get my iscsi target to run on debian

Sorry about the formatting below... Linux Microknoppix 2.6.39.3 #21 SMP PREEMPT Sat Jul 23 09:48:39 CEST 2011 i686 GNU/Linux modprobe iscsi_trgt results in FATAL: Module iscsi_trgt not ...
0
votes
0answers
34 views

Verify architecture of kernel file

Note: I am NOT interested in the currently running kernel, but on a kernel that I am going to boot and which is in a file in the filesystem. I am going to boot a new kernel. I have prepared grub.conf ...
3
votes
1answer
48 views

Kernel Compile crashing on Hyper-V due to memory issues

This is on a Hyper-V machine. I've set the min RAM to 512 and the max to 2048. The host machine has more then enough RAM. Does Linux have an issue with Dynamic RAM on Hyper-V? I can't seem to ...
2
votes
2answers
763 views

CONFIG_HOTPLUG_CPU=n - kernel panic?

I have a task to disable CPU hotplug in RHEL5 kernel (2.6.18-el5.xxx). I have no problem recompiling an own kernel from the sources with an old config. But as soon as I disable CPU hotplug, I get ...
0
votes
2answers
2k 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 = ...
1
vote
0answers
28 views

OpenVZ - updating kernel and all containers

Last night I upgraded to the latest kernel of openvz. I rebooted the host node. It came up with the latest kernel. However, the containers are still running the old kernel. What I did on the host ...
4
votes
2answers
1k views

Still getting aacraid: Host adapter abort request errors after following recommended steps

I am getting the infamous aacraid: Host adapter abort request error with my new Adaptec RAID Controller under high I/O. I have read several forums, even Adaptecs, that setting the ...
-3
votes
1answer
19 views

Is there anyway to specify the version of kernel update with apt-get? Debian 7 [closed]

Is possible to select the version of Kernel I need in apt-get? Actually, I need to update it but I had lot of configurations problems with 3.2. Or the only way is compiling the kernel? Thank you
0
votes
2answers
1k views

Kernel: Uhhuh. NMI received for unknown reason 31 on CPU 3

I'm receiving this error on "Linux Debian-70-wheezy-64-minimal 3.2.0-4-amd64 #1 SMP Debian 3.2.46-1+deb7u1 x86_64": Message from syslogd@hostname at Feb 14 02:54:51 ... kernel:[81927.464687] Uhhuh. ...
2
votes
1answer
132 views

Linux read disk cache and NFS

I am interested in the impact of the read disk cache on accessing a file through NFS. Lets say I have a file on NFS. I access it (do "cat myfile") from a linux host "A". If there's enough RAM a file ...
52
votes
21answers
16k 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 ...
1
vote
2answers
94 views

grub.conf missing initrd path after kernel update

I updated a server this morning and the latest kernel panics during boot. Upon review of the grub.conf file I found the initrd path was missing. Is there a way to fix this issue? Or should I remove ...
1
vote
1answer
117 views

CentOS only detecting 50% of ram on IBM Server

I have IBM server with 16 GB RAM installed. Initially it showed 16 GB with free | grep Mem | awk '{print $2}' but now it shows only 8116136 but it must show 16439208 When I do dmidecode ...
1
vote
3answers
474 views

Error installing new OpenVZ kernel

Seem to have an error when updating the kernel on a OpenVZ server when running "yum update" im getting the below Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * base: ...
0
votes
1answer
25 views

FTP server suddenly down

Suddenly I can not use anymore my FTP server and I get via ssh the following kernel report. I'm running on Debian 7.0 with ISPconfig3 kernel:[801112.466009] nf_ct_ftp: dropping packetIN= OUT=venet0 ...
0
votes
1answer
62 views

Healthy Linux machine immediately went down

This is the last log entry in /var/log/messages and after this the machine has been stopped. How can I debug why the machine has been stopped? I am not sure but maybe the system stops comes from the ...
7
votes
1answer
238 views

How does vm.overcommit_memory work?

When I use the default settings: vm.overcommit_memory = 0 vm.overcommit_ratio = 50 I can read these values from /proc/meminfo file: CommitLimit: 2609604 kB Committed_AS: 1579976 kB But ...
12
votes
2answers
433 views

Kernel stack trace to source code lines

Given a kernel stack trace as below, how do you determine the specific line of code where the issue occurred? kernel: [<ffffffff80009a14>] __link_path_walk+0x173/0xfb9 kernel: ...
2
votes
1answer
166 views

Is it possible to configure the Linux kernel I/O scheduler for an NFS mount?

On a normal block device you can change the i/o scheduler like this: # cat /sys/block/hda/queue/scheduler noop anticipatory deadline [cfq] # echo anticipatory > /sys/block/hda/queue/scheduler # ...
3
votes
1answer
55 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
0answers
18 views

collect previous kernel logs in linux after reboot

how to collect previous kernel logs in linux after reboot and how to search the old logs? Initially when system is rebooted the logs are not captured and found rest of the log's.But there is an error ...
1
vote
1answer
400 views

Server won't boot, kernel panic - not syncing

After a reboot of a CentOS 6.2 server we are getting a kernel panic with the following error: Kernel panic - not syncing: Attempted to kill init! Panic occurred, switching back to text console ...
0
votes
0answers
20 views

How do I configure kdump with extra_modules on ubuntu?

I need to configure extra modules to load with kdump (specifically, vga16fb.ko). On RHEL systems it's in /etc/kdump.conf, but ubuntu doesn't have this file. I've looked in /etc/default/kdump-config, ...
0
votes
1answer
64 views

Initrd and Initramfs

I have read about the differences between the two from stackoverflow. But I am still finding it difficult to understand tmpfs and the real advantages of initramfs over initrd. I find that on RedHat ...
1
vote
0answers
23 views

Kernel Compiling from Vanilla to several machines

When compiling kernels for machines is there a safe or correct way to create a template for say servers? I work with a lot of RHEL servers and want to compile them with GRSEC. However, I do not wish ...
12
votes
8answers
2k views

Is it important to reboot Linux after a kernel update?

I have a few production Fedora and Debian webservers that host our sites as well as user shell accounts (used for git vcs work, some screen+irssi sessions, etc). Occasionally a new kernel update will ...
2
votes
0answers
137 views

Linux cgroups cpuset w/ subs causes cgconfig not to start

I am having a problem trying to separate 2 groups using cpuset subsystem. This works fine, however if i go to add a subgroup to that group (in this case -- user1), cgconfig will fail to start with ...
1
vote
2answers
407 views

yum update kernel without removing old?

When I yum update it wants to remove the oldest of the 3 kernel I have and upgrade to a new. Is it possible to get yum not to remove old kernels?
2
votes
1answer
460 views

“kernel: Cannot read proc file system: 1 - Operation not permitted” — millions of such messages each minute in kern.log on OpenVZ VPS? [closed]

I'm seeing repeated never ending such messages in kern.log on my OpenVZ ubuntu 12.04 server. Mar 2 06:23:33 localhost kernel: Cannot read proc file system: 1 - Operation not permitted. Mar 2 ...
-1
votes
1answer
804 views

Server freeze with “rcu_sched detected stalls on CPUs/tasks”

My web server is crashing several times a week. I see errors in syslog but I can't find a solution. I tried changing kernel to older or newer versions but no difference. I moved everything to a new ...
2
votes
0answers
187 views

Ubuntu 14.04 / Apache 2.4 causes kernel fault on Amazon EC2 medium instance

Got a disturbing crash while performing 'apachectl stop'. General system: $ uname -a Linux www.example.com 3.13.0-24-generic #47-Ubuntu SMP Fri May 2 23:30:00 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux ...
0
votes
0answers
234 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 ...
1
vote
1answer
151 views

preventing ipmi kernel drivers from loading

I'm trying to prevent the ipmi kernel modules from loading on a server with a SuperMicro X8DTG-D motherboard running Ubuntu 14.04. My motivation for doing so is that the modules sometimes seem to take ...
0
votes
5answers
2k views

Server hang on CentOS 5.5

I'm running CentOS 5.5 on a server. It runs several VMware virtual machines and an NFS server. Occasionally, like today, it hangs. There's nothing in /var/log/messages that indicates any problem. ...
0
votes
2answers
71 views

FreeBSD Established Connections Maxing out at 300

We've previously had issues in our environment where it seemed we were reaching FreeBSDs max connection limit. We took action demonstrated by http://nginx.org/en/docs/freebsd_tuning.html and bumped up ...