The Linux kernel is the operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software.

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MySQL 5.5 degraded performance in linux kernel 3.2 compared to 2.6

Our database servers (mainly based on the Debian stable packages (=currently Wheezy) seem to have about 4 times more load for the same workload in kernel 3.2.0-4-amd64 then in it's previous ...
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Virtual Machines - Possible to Restore Replace Kernel without Rebuild?

I'm using Linux Virtual Machines (Wheezy, Linux Vserver), each with a desktop environment including Firefox. If a Virtual Machine where to be compromised (e.g., SQL injection) so the kernel is ...
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121 views

linux sever interfaces automation

I am using a CentOS server which has about 6 active interfaces with different IPs, I'd want to automatically bring down all the interfaces when any one of the 6 interfaces is down. Is there a way this ...
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373 views

no network or disk devices in Arch Linux Xen guest during installation

I'm trying to install Arch Linux under Xen as domU (Guest) from Arch Linux official 2011.08 x64 Core iso image. My web hosting offers a SolusVM control panel with ability to install custom ISOs, so I ...
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287 views

Can't resolve issue: iptables: No chain/target/match by that name

So I am trying to setup shorewall firewall on my linux vps. The vps is running ubuntu 12.10. When I type $ shorewall check I get this error. iptables: No chain/target/match by that name. ERROR: ...
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1answer
198 views

/proc/<pid>/stat children CPU time

I've been running the following command on my linux box: watch -d -n 1 "cat /proc/19866/stat" The pid above is a pid of Nginx's master process - I would expect the following fields to be changing: ...
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1answer
207 views

best practice after upgrading the kernel

Greetings ... I need to know what anyone should do after upgrading the kernel ? How to do quick check if the kernel is suited for the server's softwares , check whether if kernel is compilable with ...
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1answer
21 views

Removeing ulimit from boot / init

In CentOs as from version 6 there is a by default process limit 1024 for every user i.e /etc/security/limits.d/90-nproc.conf * soft nproc 1024 I have to execute a backend ...
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1answer
387 views

ArchLinux under Xen fails to see root fs after kernel upgrade to Linux-3.0

I bought a VPS but the hosting company doesn't have a prebuilt image for Arch Linux x64, so I have to install from ISO using VNC in SolusVM. The installation works fine, the box (Xen Guest) is ...
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1answer
54 views

CIFS error -512 on a mount

So we have Alfresco running at work and I like to have our repository mounted via CIFS: mount /mnt/alfresco/ -v mount.cifs kernel mount options: ...
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68 views

12.04 Migration Process time delay

We have an issue in our server that is the migration process in taking time and also the load in the server is getting high due to that. No LSB modules are available. Distributor ID: Ubuntu ...
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1answer
119 views

Linux not freeing the file buffer when we execute rm or > (redirection) operator

I have one router which has embedded-linux with kernel version 2.4.22 running on it. I know its very old version but i have to deal with it. Please take a look at the free command output when i run it ...
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1answer
438 views

RHEL 6.0 upgrading kernel from 2.6.32-71.el6.x86_64 to 2.6.32-358.2.1.el6.x86_64

[root@localhost ~]# rpm -ivh kernel-2.6.32-358.2.1.el6.x86_64.rpm error: Failed dependencies: bfa-firmware < 3.0.3.1 conflicts with kernel-2.6.32-358.2.1.el6.x86_64 [root@localhost ~]# rpm ...
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1answer
150 views

Issues with Xen Kernel and Debian

My Xen installation has gone weird on me and I am trying to get back to normal. I overflowed the base partition and in my haste to delete unused files I think I deleted something important, so now ...
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1answer
358 views

Debian Wheezy No longer booting. Freezes after setting kernel variables

My Debian (Wheezy) server has been running smoothly for a very long time with no indications of any problems. I had it running 24/7 so it was always on. The other day my power went out and when I ...
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1answer
393 views

CentOS 6.3 with kernel-ml(3.7.1-2.el6.elrepo.x86_64) - No Console Output

I installed kernel-ml(3.7.1-2.el6.elrepo.x86_64) from elrepo on CentOS 6.3, and everything is working fine, except that I see nothing on the console and can't interact with it. I can SSH to the ...
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1answer
1k views

CentOS 6.3 task blocked for more than 120 seconds

Recently have been getting Zabbix alerts about our mail system being unavailable, the uptime on the machine is 30+ days. I've been tracing the Zabbix logs and it looks like the communication between ...
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1answer
379 views

How to stop a infinite running process(ztail) started by a ssh session after that session is closed

I have a peculiar problem. My server supports multiple ssh session simultaneously, so that multiple admins can manage it simultaneously. We have a command which calls ztail to show the compressed log ...
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1answer
196 views

what is occupying linux low memory

How can I find what is occupying my low memory on 32 bit Linux OS? cat /proc/meminfo |grep Low LowTotal: 812908 kB LowFree: 43340 kB Regards,
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1answer
174 views

How to disable specific CPUs in Linux 2.6.26.2

I have an old machine running Linux kernel 2.6.26.2 which is behaving oddly. I suspect ONE of the CPUs is possibly heating faster than the other. I want to run some tests with specific CPUs/cores ...
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1answer
236 views

Adding Linux kernel command line parameters

I would like to increase the size of the vmalloc region from the default value, and pass vmalloc= as a command line parameter while booting. I am booting a uImage. In which file do I need to add the ...
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1answer
193 views

Xen dom0 crashed

Lots of questions this week, I got this error on dom0, then the server crashed (according to /var/log/messages): Jun 22 10:02:09 453 dhcpd: DHCPACK to xx.xxx.xxx.xx (xx:xx:xx:xx:xx:xx) via eth0 Jun ...
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1answer
205 views

Linux Kernel Usb Printer Device Class driver

I am trying to update the CUPS daemon on my QNAP NAS, which runs a flavor of *nix. The entire OS system is loaded on a RAMDISK when the NAS boots so I've come up with a script that runs at start-up ...
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237 views

ionice or chrt for Bonnie benchmark

I am running Bonnie benchmark on an embedded device and I am getting variable results for every run. I am contemplating using ionice and / or chrt to get around it. Can you suggest which option is ...
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210 views

Storage drives is causting system crash

I'm running Centos 5.4 with 750GB(ntfs) and 2TB drives for storage. Originally I installed the 750, everything seemed fine and then I installed the 2TB drive with NTFS already partitioned. I noticed ...
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218 views

linux initcwnd and initrwnd via /etc/sysctl.conf

Folks, As we know, the 3.x kernels have higher TCP default connection values, such as initcwnd and initrwnd. For 2.x friends, is there a way to set these in /etc/sysctl.conf instead of the ip route ...
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Sun Fire V40z, big gap between memory reported by dmidecode and what the Linux kernel sees

I'm looking after a V40z (a loaner), running RHEL 4.8 (no, I can't update it, it's a loaner) that according to dmidecode has 8 DIMMs of 2048M each, which makes for 16GB RAM as far as I'm concerned. ...
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297 views

netmap issue with wheezy linux kernel 3.2.0.4 and Intel Corporation 82599EB 10-Gigabit card

I have compiled the netmap drivers on debian wheezy with kernel 3.2.0.4 and ixgbe patched module from netmap drivers code. When I insert the modules after removing default ixgbe module I get the ...
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322 views

KVM host kernel configuration for best performance

I'm currently building a kernel for my server, which should serve for hosting virtual machines using KVM. There are a few kernel configuration options that are already described in the KVM-Wiki. The ...
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24 views

__ticket_spinlock high cpu

We are having a strange problem on our Ubuntu 10.04 KVM infrastructure, where periodically, one of two vm webservers freaks out, with persistently high load, even if we restart the applications. (the ...
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225 views

Linux Kernel complaining about TSC when selected clock source is Hyper V

We are running RHEL 6 boxes on HyperV with Windows Server 2012. On a few on our RHEL boxes, I am seeing this error in /var/log/messages kernel: Clocksource tsc unstable (delta = -62519781 ns). ...
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43 views

ext3 option on error doesn't work

I have a redhat server 5.8 with ext3 on top of lvm, i noticed ext3 has setting "Errors behavior: Continue" in the fs super block, from the man page of mount command i readed this ...
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101 views

Should I set rto_min for a route inside data center?

We have a few dedicated server rented in a data center with debian 7, kernel 3.2. We use one of those servers as a database server. The network between our application server and database server is ...
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112 views

Capturing on loopback device on Ubuntu LTS: 15 Mbit of traffic and “x dropped packets”

I am trying to capture about 15 Mbit of traffic on the loopback device on Ubuntu LTS using tcpdump, and I am seeing dropped packets. The CPU is a freaking i7, and i have yet to see CPU usage go above ...
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277 views

Kernel panic - not syncing: VFS: Unable to mount root

I uploaded a centos 6.2 VMDK to s3 and then converted it to volume using ec2 import volume. Then i took the snapshot of the volume and deleted it.Now I am trying to create a instance from the snapshot ...
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84 views

linux kernel configuration to filter multicast traffic based on interface

I have two virtual interfaces (eth0.2, eth0.3) in my PC. I am sending multicast data from eth0.2 to eth0.2. Multicast data is received in eth0.2 but also received in eth0.3, the other virtual ...
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176 views

Tracking huge buffer usage under Linux

I'v a Linux server running under Debian Lenny with 4Go of RAM. It doesn't run a large number of stuffs: Postfix/spamassassin (daemon mode) Bind9 KVM (one guest - 1Go of RAM for it) Every day at ...
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546 views

How to modify Ubuntu 10.04.1 Grub entry for supporting KGDB kernel image

I am trying to update target m/c grub.cfg file for KGDB setup but while booting the m/c it got hung completely and not asking/waiting for remote gdb connection. Following is the entry which I added:- ...
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5 views

Ignoring Uboot's cmdline using a pre-built one

I'm trying to compile a custom Linux kernel for my tablet, but, for debugging purposes, I have to use my custom cmdline. The U-Boot passes to the kernel his own cmdline, but it's not suitable. I can't ...
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24 views

Cannot enable NMI Watchdog on HM65 Core i5

I'm trying to enable the NMI Watchdog on Linux on an AFL-12A-HM65 touch screen with an Intel HM65 Core i5 CPU. The user manual has an implementation for DOS (real helpful) but not for Linux. There ...
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35 views

Server crash : “unable to handle kernel paging request”

My fresh new Ubuntu webserver randomly crashes with the following error in the syslog. It doesn't respond anymore and I have to do a hard reboot. It happens almost one time a day. Server kernel is : ...
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24 views

How can I suppress rtc error messages in a CentOS 6 PV DomU?

We run a number of CentOS6 PV DomUs. Now logwatch reports afer reboot rtc-errors of this type: kernel: platform rtc_cmos: registered platform RTC device (no PNP device found) rtc_cmos: probe of ...
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29 views

ocfs2 with pacemaker cluster, space used 5.8G

I have a corosync+pacemaker cluster with suse 11 sp2, i created 1 million of files, using this script for testing the defrag problem #!/bin/bash i=1 until (false) do for k in `seq 1 100`; do ...
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125 views

KVM - task foo:1234 blocked for more than 120 seconds - howto change task scheduler

I recently installed a new Debian Wheezy server with KVM (the "KVM Host") then installed a Debian VM on the KVM (the "VM"), and got very bad performance on the VM. Looking through dmesg on the VM, I ...
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147 views

Kernel update on Xen CentOS

Running a "yum update", CentOS try to install a new kernel. However, I get this: Installing : kernel-2.6.32-358.6.2.el6.x86_64 1/1 grubby fatal error: unable to find a suitable template ...
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137 views

which `install.sh` does `make install` use?

I am trying to learn what make install does in the context of building a custom kernel. (reference: ...
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436 views

How do I check my Linux kernel against root exploits?

I keept hearing about Linux root exploits lately and I'm beginning to become worried. Ever since Linux switched away from the stable-unstable versioning scheme, distributions began to adopt a wide ...