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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1answer
37 views

I need to perform a kernel upgrade on a live system. Best practices? [on hold]

Steps taken so far: apt-cache search linux-image* apt-get install linux-image-... I was now thinking of rebooting and selecting the new kernel when it appears on the GRUB menu, however: Is it ...
1
vote
2answers
532 views

Hotplug area too small error

I have VM running under RHEL6, which is running under HyperV. It has a lot of important soft installed, but does not have suffocating workload (~10% CPU is used). It's been really unstable recently ...
0
votes
1answer
29 views

VPS restarted for no reason. Why?

I have a VPS that runs a Java server, a redis server and a PostgreSQL server. Everything is running well but last night my server "crashed" at 3:15:50 AM. At least that's what I thought. I looked at ...
1
vote
3answers
64 views

Best way to disable swap in linux

I am running a custom compiled 3.18.9 kernel and I am wondering about the best way to disable swap on the system. I also use init if it makes a difference. Is it enough to comment or remove the swap ...
0
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 ...
5
votes
3answers
5k views

Interpreting cryptic kernel “page allocation failure” messages

I have a multi-user CentOS 6.1 database system running an application named ABC. The server is 64-bit, 8GB RAM and 6 vCPU (on VMWare ESXi 4). We get frequent dumps into the dmesg and the system logs ...
7
votes
4answers
24k views

In CentOS 6.x, how can I upgrade to Kernel 3.4?

I have a server running CentOS 6.2 with kernel version 2.6.32, but I need to increase my application Performance. The Kernel Version 3.4 has x32abi which can improve the performance so i want to ...
1
vote
0answers
9 views

Seeing what Linux kernel compile options where used [duplicate]

Is it possible to tell what compile options a running Linux kernel has been built with? I am particularly interested in those that impact on preemptive behavior, such as CONFIG_PREEMPT_VOLUNTARY. ...
1
vote
1answer
39 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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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 = ...
0
votes
1answer
51 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: ...
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. ...
12
votes
1answer
6k 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 ...
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
1answer
29 views

IO does not share in multiple CPU

In my linux server IO doesnot share in multiple CPU. as below output ata_piix intrupts share in only cpu0 [root@manage ~]# uname -a Linux manage 3.14.24-1smp #12 SMP Tue Mar 17 15:33:27 IST 2015 ...
0
votes
0answers
19 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 ...
3
votes
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 ...
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votes
1answer
35 views

Debian diffence between kernels [closed]

Debian Wheezy installer What's the difference between the first and the second kernel?
5
votes
2answers
2k views

Removing stubborn modules

I'm trying to programatically stomp on bluetooth on RHEL5. I've got the service stopped -- no problem. Also no problem on rpm -e for the associated bluetooth packages, bluez-*. ps -aef | grep -v ...
1
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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 ...
0
votes
0answers
17 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
1answer
99 views

SSD caching using bcache or dm-cache on kernel 2.6.32-042stab104.1

I'm looking to use bcache or dm-cache with the latest OpenVZ kernel (2.6.32-042stab104.1) on CentOS 6. Unfortunately, dm-cache and bcache are part of kernel 3.10, but I know the OpenVZ kernel has a ...
0
votes
1answer
539 views

What kernel module to compile for getting QOS service on Linux

We are developing on Linux system whose kernel had been compiled without QOS service years ago. Currently we want the QOS service back and plan to compile only the QOS-related kernel modules and ...
3
votes
4answers
2k 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: ...
26
votes
6answers
24k 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 ...
0
votes
3answers
68 views

Kernel Processes Periodically Eating CPU During High Load

I run a production web server with 24 cores in which the work is both CPU and I/O intensive, but mostly CPU. My scripts delay execution when total CPU load is ~85% or higher in order to keep the load ...
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
1answer
53 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
vote
1answer
41 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 ...
0
votes
1answer
117 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 ...
8
votes
2answers
554 views

Why “lsmod | wc -l” not equal “ls /sys/module | wc -l”

Why do these two commands return different results? lsmod | wc -l 100 ls /sys/module | wc -l 138
0
votes
0answers
25 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
2answers
61 views

Can a Linux Kernel be shared between two operating systems?

Quite simple question. I am working on a project to have multiple operating systems (all linux) on the same machine using btrfs subvolumes so that the user can boot to the environment they are ...
0
votes
0answers
61 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) ...
11
votes
2answers
10k views

How do ulimit -n and /proc/sys/fs/file-max differ?

I notice that on a new CentOS image that I just booted up off of EC2 that the ulimit default is 1024 open files, but /proc/sys/fs/file-max is set at 761,408 and I'm wondering how these two limits work ...
1
vote
0answers
110 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 ...
2
votes
0answers
827 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 ...
1
vote
1answer
2k views

File-descriptors setting on /etc/sysctl.conf

I have recently learnt that to be able to increase the amount of virtualhosts that we can serve via Apache depends on file-descriptors. they say the value should be added to /etc/sysctl.conf as ...
2
votes
1answer
44 views

Use VPS provider's kernel or maintain my own?

I've got a Debian Wheezy VM on Linode and they run it with their own kernel. As a reputable company, I'm sure they're quick to apply security patches, and all I need to do is reboot to get the new ...
0
votes
1answer
1k 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 ...
1
vote
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 ...
0
votes
1answer
76 views

New linux with old kernel in chroot [closed]

I have access to enterprise level server, but it have kernel version Description: Red Hat Enterprise Linux Server release 6.4 (Santiago) Release: 6.4 Codename: Santiago ...
0
votes
1answer
38 views

Enable IP forwarding inside an OpenVZ container but disable it on host

Is it possible to enable IP forwarding inside an OpenVZ container but keep it disabled in host system? I understand that OpenVZ containers and host share kernels, but I can use sysctl to set ...
0
votes
0answers
75 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 ...
2
votes
0answers
77 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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votes
2answers
278 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 ...
15
votes
2answers
297 views

Does the “bs” option in “dd” really improve the speed?

Every now and then, I'm told that to increase the speed of a "dd" I should carefully choose a proper "block size". Even here, on ServerFault, someone else wrote that "...the optimum block size is ...
0
votes
1answer
31 views

What does the tcp_fastretrans_alert error mean?

I found this error a couple of times in /var/log/messages after experiencing some odd TCP behavior: For some reason, if I connect to for example SSH for the first time in say an hour, the connection ...
0
votes
1answer
47 views

Which is the physical device behind the logical /dev/___ device

From time to time I get myself dealing with this same problem: from a linux logical block device (something below /dev/), I need to find the actual hardware behind it (something probably being listed ...
1
vote
0answers
39 views

make linux kernel read swap back into memory [closed]

Occasionally, I run a script that uses the majority of the 16GB of physical memory on my workstation. The kernel then swaps out the rest to swap partitions on multiple disks. After the script is ...