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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2answers
701 views

Kernel updates without rebooting

Similar to some of the topics touched on in this question, Rebooting servers for kernel updates, I was curious if there was a way in which one could apply kernel updates to the system without ...
0
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1answer
310 views

adding new scheduling policy to the kernel

i'm working on a redhat 8 linux and i want to add new policy for scheduling the processes , could you help me with : 1) where to define the new policy 2) how does the process of assigning a policy for ...
8
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1answer
7k views

Flush processes consume too much of CPU

The Server is EC2 Instance, it stands for saving files to NAS (NFS) from HTTPD. The processes like flush-0:32 consume over %90 of CPU and load average: 65.50, 64.02, 66.59. According the graph, it's ...
0
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2answers
926 views

Linux kernel upgrade broke : How do I remove the kernel that broke it all?

I just upgraded an Ubuntu 10.04 (Server Edition) to '2.6.32-36'. However, after doing that upgrade the server would not longer start and GRUB tells me that it is unable to read the header. I rebooted ...
2
votes
3answers
488 views

netconsole or serial logging in XenServer DomU

I have some problems with stability of Debian guests in my XenServer hosts. To debug this problem I wanted to use netconsole kernel module, unfortunately, because the Ethernet controller is emulated, ...
0
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1answer
235 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 ...
2
votes
2answers
667 views

Time drift in Cloud Server - need to mainpulate GRUB config

We are hosting a VPS on a popular host and are experiencing a regular time drift of several minutes a day forward (approx 7). Linux Kernel: 2.6.18-164.11.1.el5 GNU/Linux Distro: CentOS release 5.4 ...
2
votes
1answer
1k views

Can't find the pdflush thread?

I just found out there's no pdflush on my Linux, v2.6.38. But when I do a ps uax | grep flush It shows: root 269 0.1 0.0 0 0 ? S 13:05 0:04 [flush-8:0] My kernel is: ...
0
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2answers
3k views

ESXi :: vmxnet3 vNIC and Linux kernel errors

a long shot, but figured I'd give here a try (no solution on VMware community forum). In a Linux guest (CentOS 5.7 64-bit) with vmxnet3 vNIC we are getting a few hundred kernel errors per day on ...
4
votes
1answer
4k views

how do i set hard and soft file limits for a non-root user at boot?

I have a xen HVM vps and I'm trying to raise the hard and soft file limits for nobody at boot time. I'm using Ubuntu 10.04.3 and inside /etc/security/limits.conf I have: nobody soft nofile ...
1
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1answer
1k views

Does Linux support IPsec service out of the box?

As per subject. I have heard of default IPsec support on later versions of Linux kernel (without need to recompile or install special packages) but maybe it's a rumour? Interested in both VPN ...
1
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1answer
2k views

Debian squeeze kernel backports upgrade - moving forward?

It was suggested to update my Debian Squeeze kernel to something more recent. We chose 2.6.38 and used Debian Backports to install linux-image-2.6.38-bpo.2-amd64 following these instructions ...
3
votes
1answer
3k views

Linux kernel crash - any ideas?

Been getting these runaway conditions on a lightly loaded vps (debian squeeze kernel 2.6.38-bpo.2-amd64, 2GB, SSD) - top load is nothing , then jumps to 30.0 & everything grinds to a halt. I'm ...
1
vote
1answer
229 views

Need rpcsec_gss_krb5 and Linux kernel 2.6.35+ on EC2

I am trying to do Kerberos-auth:d NFS4 on EC2. In order to do this, it seems one wants a kernel at least 2.6.35 in order to get decent encryption algos. The distro I could find that provides this is ...
1
vote
3answers
676 views

Where to download the latest 2.4.x Linux kernel while kernel.org is down?

I need to run the pre-paleolithic (10 years old!) SuSE 7.3 under VirtualBox. (Don't ask. I just do, ok?) I managed to successfully install it. It boots. It recognized the virtual NIC (pcnet32 module) ...
4
votes
1answer
10k views

why is kswapd using high CPU on an idle system?

I have an idle Linux centOS system and yet kswapd is using 100% cpu. All I have running is a single bash session with top running.... I have 32G RAM and yet kswapd is constantly using 100% cpu for ...
1
vote
3answers
7k views

Should I use the Linux 2.6.x or 3.x kernel on a production server?

I'm given a number of kernel options (I'm hosted on linode - all kernels are customized by linode): Latest 2.6; Latest 3.0; and the latest legacy 2.6.18 or so and more. Will there be much difference ...
0
votes
2answers
541 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 ...
1
vote
1answer
420 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 ...
0
votes
3answers
1k views

How to view linux kernel logs online?

I have a kernel module logging input of some sensor while I work with it. I want to see if there is a command that outputs /var/log/messages (for example) but waits for more logs to come. That is, ...
0
votes
1answer
427 views

How to fix “disappeared” memory after Linux 2.6.18 Kernel?

Moved from here: http://stackoverflow.com/questions/7070640/how-to-fix-disappeared-memory-after-linux-2-6-18-kernel I think there is currently a known issue that there are some issues with memory ...
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2answers
3k views

Log - Server kernel: INFO: task httpd:000000 blocked for more than 120 seconds

Almost everyday my server is crashing due to hight server load, and even restarting apache or mysql can't solve the problem. I need to reboot the server to solve, or it crash again due to the high ...
10
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2answers
9k views

How can I tune the initial TCP retransmit timeout?

The initial TCP RTO value of 3s is too long for most LAN-based applications. How can I tune it lower? Is there a sysctl?
1
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2answers
481 views

Linux Kernel Oops - source unknown

hopefully someone can help interpret what is going on here: [ 2081.280253] BUG: unable to handle kernel paging request at ffff8801ad287000 [ 2081.280262] IP: [<ffffffff8000f549>] ...
0
votes
2answers
866 views

Removing a module currently in use

I want to remove a module currently in use in linux. Module name is say i915 (display module) rmmod i915 shows Module currently in use. Similar output using rmmod -f i915 and it is not dependent on ...
2
votes
1answer
1k views

Optimize linux for serving http static content

What would be the system tunables to enhance serving static content? Like increase/decrease swappines, how to max out disk caching and so on...
0
votes
1answer
2k views

How to detect memory leak in the linux kernel 2.6.29

Is there a way to find out if Linux kernel is leaking memory by running some commands? I am almost positive that the linux kernel is leaking memory. However, the top and free -k do not reveal much. Is ...
0
votes
2answers
1k views

VMware player and ubuntu 11.04

I'm trying to run VMware player 3.1.4 on the latest ubuntu (11.04), but it fails to launch saying: Kernel Headers for generic pae not found. C header files matching your running kernel were not ...
1
vote
1answer
285 views

How to block everything with IPTABLES?

I would like to block everything EXCEPT SSH/FTP/HTTP/POSTFIX and MySQL. With "everything" I mean all the other ports, block pings etc etc.
3
votes
2answers
10k views

What is mdev and how to /dev/* nodes get created in Linux?

Our Linux kernel is 2.6.31 running on an embedded MIPS processor with busybox. The initialisation script (rcS) starts mdev with: echo "/sbin/stbhotplug" > /proc/sys/kernel/hotplug mdev -s Can ...
1
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0answers
207 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 ...
0
votes
1answer
275 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 ...
3
votes
3answers
3k views

PostgreSQL won't start because it “Cannot allocate memory”

I'm running PostgreSQL 8.4.5 on Ubuntu 10.04. I run an EC2 instance with a few sites running on nginx. Most of these sites run on Django and connect to this Postgres instance. For some reason, at ...
0
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1answer
80 views

About kernel upgrade

If I upgrade the kernel,will old binaries use new version of .so or still the old version? UPDATE Why kernel has nothing to do with .so?
0
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5answers
2k views

Very low performance of raid6

I noticed that writing to raid-6 is very low, but when I make tests with hdparm the speed is reasonable: dd if=/dev/zero of=/store/01/test.tmp bs=1M count=10000 Gives: 50Mb/s or even less. The ...
0
votes
0answers
272 views

how to enable ipv6 in redhat

can anyone tell me how to enable ipv6 support in rhel i tried sysctl -w net.ipv6.conf.all.forwarding=1 and echo 1 > /proc/sys/net/ipv6/conf/all/forwarding and did service network restart but still i ...
0
votes
1answer
4k views

How to compile the kernel with debug symbols? [closed]

I've already finishing compiling the kernel from source, but how to compile it with debug symbols,what additional steps to I need to take?
0
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2answers
4k views

What can be the reason for “Invalid module format”?

I'm following the steps to compile kernel 2.6.32 from source, and have no problem to go the the last step: ... make modules_install make install And I've also configured grub.conf correctly. But ...
7
votes
3answers
7k views

How can I see logs in a server after a kernel panic hang?

I am running a production gentoo Linux machine, and recently there was a situation where the server hung in my co-located premises and when I got there I noticed that the server was hung on what ...
5
votes
1answer
1k views

Linux buffer cache effect on IO writes?

I'm copying large files (3 x 30G) between 2 filesystems on a Linux server (kernel 2.6.37, 16 cores, 32G RAM) and I'm getting poor performance. I suspect that the usage of the buffer cache is killing ...
1
vote
1answer
96 views

Is upgrading your kernel analogous to patching in Windows?

Coming from mostly a Windows background, it seems to me that updating your kernel in Linux is essentially the same idea as patching the OS in Windows. Is this the case? What are the commonalities and ...
1
vote
2answers
373 views

linux kernel buffer memory is zero

There are one qestion that i can`t find in google. I have many linux boxes mostly with SLES or openSUSE, diffrent versions and kernels. On some of them i faced with slow oracle transactions problem. ...
4
votes
1answer
664 views

Meaning of tcp_delack_min

the current Linux Kernel (e.g. 2.6.36) uses Delayed Acknowledgments (delack). In /include/net/tcp.h it says: define TCP_DELACK_MIN ((unsigned)(HZ/25)) So, for a Kernel using a HZ value of ...
0
votes
1answer
43 views

enabling ipv4 forwarding locked up machine. ideas?

Hey. I'm running cent 5.5 64-bit, 1 nic, eth0. I enabled ipv4 forwarding via: echo '1' > /proc/sys/net/ipv4/ip_forward and the machine locks up. cant switch ttys cant ssh into it. Had to hard ...
4
votes
1answer
3k views

Our embedded linux system won't recognize a USB Device if it is plugged in before powerup. Suggestions?

We are developing on a small embedded device. This device us a gumstix overo board running OpenEmbedded linux. We have our development almost completely done, and have run into the strangest of bugs ...
1
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1answer
656 views

exploit.so dmesg errors

A server (which has since been pulled offline and is scheduled to be wiped) was compromised through ssh brute force. No root/su/sudo access was gained but I started observing these errors (pasted ...
0
votes
1answer
1k views

Ubuntu 8.04 LTS Hardy: Upgrade kernel to 2.6.32?

I am facing an incompatibility issue between Ubuntu 8.04 LTS (Hardy) and the PERC 6/i RAID controller on our Dell PowerEdge R710 servers. Various forum posts (Ubuntu forum) confirm that other users ...
1
vote
0answers
599 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:- ...
0
votes
2answers
115 views

Building and installing a kernel that can mount / from an EXT3 on an LVM2 device

I have an ageing but much loved Fedora Core 6 box for which I am attempting to compile a kernel more recent than 2.6.22, in order that I might employ its support for an eSATA card. My Fedora box has ...
0
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1answer
228 views

Possible to write an implement of RAIDZ or RAIDZ2 for the MD driver in the Linux kernel?

I am curious on if it is possible to have an implement of RAIDZ and/or RAIDZ2 in the MD driver in the Linux kernel? From my understanding of it is that the RAIDZ version is equivalent to a RAID 5, ...