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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380 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 ...
3
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1answer
1k views

CentOS Tuned Equivalent For Debian

Running a few systems, a few are Debian which have been great. I have on the CentOS boxes tuned(tuned-adm) installed and setup for throughput. I searched all over Google and only found some articles ...
2
votes
1answer
118 views

High shmmax value in Redhat 6.3

We are using Redhat 6.3 with 30G RAM to host our Postgres server. The (default) shmmax value is 68,719,476,736 In some forums I have read that having an shmmax value larger than the RAM causes ...
2
votes
1answer
337 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: ...
1
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1answer
40 views

TSC missing from available clocksources

Not sure why TSC as a clock source is not available? cat /sys/devices/system/clocksource/clocksource0/available_clocksource hpet acpi_pm The CPU I'm using is Intel Xeon(R) X5570 @ 2.93GHz. The ...
1
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1answer
42 views

how to debug futex congestion in system

I have perl multithreaded script ("assp antispam proxy") that uses multiple perl libraries. On one of my servers after about 2 hours script starts to make huge number of futexed which consumes a lot ...
3
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0answers
247 views

Monitoring Linux Kernel Space Processing

I'm running two "services" that are served in linux kernel-space: Linux Netfilter Firewall ("iptables") Linux Virtual Server Loadbalancer ("IPVS", "LVS") Now I want to (performance-)monitor my ...
2
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0answers
78 views

BUG message on xenserver 6.5 - bad memory?

Several times a day I receive the following error in /var/log/messages. The server hangs and requires a reboot to respond again: Feb 1 13:44:54 xenserver-abfuqvrs kernel: [35023.166776] BUG: unable ...
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0answers
831 views

OpenVPN ERROR: could not insert 'tun': Unknown symbol in module, or unknown parameter (see dmesg)

I'm trying to configure OpenVPN on my Debian 7 VPN but I'm getting the following error ERROR: could not insert 'tun': Unknown symbol in module, or unknown parameter (see dmesg) I tried the ...
2
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0answers
279 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 ...
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0answers
162 views

Redhat 6.4 configured to log Martian packets but is not logging ll header

I am trying to investigate the source of martian packets I have been seeing on several servers connected to the same subnet. The logging of martian packets has been enabled in /etc/sysctl.conf. ...
2
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0answers
111 views

Upgrading kernel on Debian server hosting Xen 3.2.1

I have a physical server running Debian 6 and Xen Hypervisor 3.2.1, and kernal -a says "2.6.26-1-xen-amd64". I have not updated for a long time, because when I run apt-get upgrade, one of the updates ...
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vote
0answers
31 views

detecting whether GPUs are accessible before running nvidia-smi during boot to create dev files

In the past, I've successfully configured Ubuntu systems containing NVIDIA GPUs to launch nvidia-smi in the background from within /etc/rc.local during the system boot to create the requisite ...
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0answers
76 views

Upgrading CentOS from 6 to 7 has broken my boot sequence

I ran the upgrade assistant provided by CentOS for upgrading from CentOS 6 to 7. The upgrade appeared to have been a success, however my system now hangs when trying to boot up. (Keep in mind I have ...
1
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0answers
369 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 ...
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0answers
71 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 ...
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0answers
603 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 ...
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111 views

Linux kernel module “Unknown parameter” stops module from loading. How to load module anyway?

The following is happening on a Ubuntu 10.04 system I'm working on: The kernel is shipped with e1000 driver module version 7.3.21-k5-NAPI. This version of the module is causing problems. To fix, the ...
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vote
0answers
24 views

Process identifier mask in z/OS

I've noticed a curious pattern to process identifier numbers on the z/OS system I'm working on (uname reports it as OS/390), they're either 1-4 digits long or 8 digits long but never in between. The ...
1
vote
0answers
235 views

demonstrate Automatic Hardware Clock Synchronization By the Kernel (11 minute mode) without ntpd

From the man page of hwclock: This mode (we'll call it "11 minute mode") is off until something turns it on. The ntp daemon xntpd is one thing that turns it on. You can Ok, I have a ...
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0answers
167 views

iptables xt_recent change in kernel without modules

is it possible to change xt_recent module parameters when it is compiled into kernel ? most of the info on internet suggest setting it by modprobe but that is not the case in my setup as I have ...
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0answers
236 views

FreeBSD XEN kernel not booting in XenServer 6.2

I have a XenServer 6.2 host, and I am trying to get a FreeBSD-9.1-i386 guest to run in PV mode. The installation of the guest is fine, but after a reboot with the new kernel the system does not boot. ...
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vote
0answers
361 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: http://i.stack.imgur.com/wAI20.png When I try adding no-bootscrub to the kernel ...
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0answers
335 views

CentOS 6 won't load default (new) kernel, loads (another) older one instead

I am having a weird issue with a CentOS 6 system. I have upgraded the kernel twice now and when I reboot the system it still loads the older kernel. I also had a dc tech watch the screen as it ...
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0answers
333 views

UDP socket receive buffer size change on RHEL6.3

Our system used to work on RHEL5.3 And the socket receive buffer size is 64k. And that works fine. We can get message size up to 64k on UDP socket. But after system upgrade, it is running on RHEL6.3 ...
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0answers
722 views

“sched: RT throttling activated” KVM host - what does this mean?

Ubuntu 12.04 64bit - under a KVM parent. 32 cores. So we seem to be having some load issues. We have noticed this line in kern.log: "kernel: sched: RT throttling activated" What does this mean? Is the ...
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0answers
201 views

what does setting kernel.shmall too high do?

I'd like to know what the kernel does when the value of kernel.shmall works out to being larger than the total amount of available memory (main memory + swap space). Is the value ignored and the ...
1
vote
0answers
296 views

Ubuntu - random reboot since 3.0 kernel

I have an Ubuntu Server that is now upgraded to 12.04 LTS server. Ever since I've upgraded from 10.10 to 11.04, when the kernel went from 2.6.38 to 3.0.anything, my machine would constantly randomly ...
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0answers
176 views

Find counts of ulimit quotas

So, we may have some sort of zainy leak in our software. We're using Mono and spawning many processes over the course of weeks/months. Eventually, we can't spawn anymore on our clients machines. It ...
1
vote
0answers
385 views

Does TIME_WAIT affect dynamic ports?

I've read a bit about TIME_WAIT connections, and know they should be harmless to my server (connection closed, so no resource connected with this socket). Recently, my server reached the magic ...
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0answers
153 views

Would OOM_Killer succeed if SIGKILL didn't?

Last week an user application turns out to hog one of my servers. It was exhausting the memory gradually and slowly. When I attempted to kill -9 PID the PID went in state D. While this was eating the ...
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votes
0answers
6 views

convert SLES11 SP1 vmlinuz-3.0.13-0.27-xen to VMware using vmware converter

I am looking to convert a XEN VM (SLES11 SP1 kernel vmlinuz-3.0.13-0.27-xen) to a VMware guest using the VMware converter tool. The VMware tool tell me conversion went fine. 100% OK, however, when I ...
0
votes
0answers
44 views

Kernel panic under DDOS

I'm running a Debian 6 - 64bit system (Kernel 2.6.32-5-amd64) and often get flooded with DDOS. I have tuned the network parameters under /etc/sysctl.conf to not let any kernel parameter overflow. ...
0
votes
0answers
29 views

switch_root not included in initramfs image

After upgrading the kernel via yum to the latest version the initramfs image file is missing the switch_root binary from the /sbin/ folder. This causes the machine to not boot, from this kernel. ...
0
votes
0answers
20 views

Why would kern.log stop logging after crash & reboot

Server: Ubuntu 12.04 I recently noticed that my servers kern.log had stopped logging. I've not separated iptables from the kern.log so it used to be very active, however recently it's been logging ...
0
votes
0answers
18 views

Run compiled kernel with mcp251.x support

I have jetson tk1 board with ubuntu 14.04 pre-installed. I want to add mcp2515 functionality to it. How can I get it running? First of all, I set up the support of can bus in kernel and make and ...
0
votes
0answers
20 views

Broadcast ARP weirdness

we a running a router on a custom Linux box. Kernel is 3.14.14. What happens is that when you arping the router in broadcast only mode is the router has a verey slow response time: # arping -b -c ...
0
votes
0answers
26 views

Network Interfaces Cards and rx_short_length_errors and Linux Kernel

My machine (Linux OS) is counting packets with wrong length, it is a huge environment (GW's, Routers, Switches...) , so I would like to understand how NIC's behaving with these packets. -Does NIC's ...
0
votes
0answers
62 views

Cannot start OpenVZ container

When I try to start container I got Starting container... Opening delta /var/lib/vz/private/100/root.hdd/root.hdd Adding delta dev=/dev/ploop15117 img=/var/lib/vz/private/100/root.hdd/root.hdd (rw) ...
0
votes
0answers
76 views

How to find what is causing a Kernel EventTracing error in the Event Log?

I am troubleshooting a Kernel EventTracing: "session failed to start with the following error: 0xc0000011" that pops up too many times in my event log. Every solutions I found in google were very ...
0
votes
0answers
31 views

How does a kernel patch propagate into distribution updates?

I have been affected by, and helped to debug, a kernel bug. A patch has been created by the maintainer of the module, and submitted. I am interested to know how the patch propagates through to binary ...
0
votes
0answers
12 views

EXSI4.0. 2 different kernels - one boots other locks up immediately, how to check initrd difference

I have a ESXI4.0.0 (v4) host, where I am trying to install a guest. The host machine is a regular Intel PC. I have 2 different ISO images (heavily modified version of SLES for a commercial product), ...
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votes
0answers
123 views

How will updating kernel affect everything else?

I'm new to Linux and I'd like to try to upgrade kernel on my little NAS, but I don't really know how it will affect installed packages and user files, and do I really need to upgrade it? Plus the ...
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votes
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193 views

Strange memory usage behavior in GlusterFS machines

I'm running into a strange high memory usage problem in my environment. I have a two GlusteFS nodes that are serving 26 replicated volumes. Each morning, both servers will consume the majority of all ...
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votes
0answers
263 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: ...
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votes
0answers
129 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 ...
0
votes
0answers
42 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
0answers
567 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 : ...
0
votes
0answers
134 views

Java causing kernel panic

I'm running quite a lot of computations on Ubuntu 12.04 (3.8.0-35-generic), application is written in Java (Oracle 1.7.0_45-b18) on a server which has 12 AMD cores. Typically the computations uses 10 ...
0
votes
0answers
131 views

Why does firehol generate an iptables ACCEPT rule on top?

Firehol generates iptables rules from a convenient configuration file. In my /etc/firehol/firehol.conf I have the following very simple configuration to allow incoming connections on http, https and ...