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.

learn more… | top users | synonyms

1
vote
3answers
6k 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
515 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
416 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
415 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 ...
1
vote
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 ...
9
votes
2answers
8k 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
vote
2answers
460 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
804 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
1k 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
282 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
9k 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
vote
0answers
203 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
268 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
votes
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
votes
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
259 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
3k 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
votes
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
352 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
636 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 ...
3
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
vote
1answer
633 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
986 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
592 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
113 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
votes
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, ...
0
votes
1answer
158 views

How can i break my own linux kernel [closed]

I was reading the linux book which says this Finally, if you break your kernel or boot loader, you won't be able to get to single-user mode without extra help. You can often boot your system ...
0
votes
2answers
1k views

Kernel panic almost daily, why?

Running latest version of CentOS 5 64. Get these almost daily, at totally random times. The box is a file delivery machine, that usually sends around 2.3Gbit Message from syslogd@localhost at Jun 28 ...
1
vote
2answers
2k views

Will modules installed by insmod command persist after rebooting?

There is how the book I'm reading describe the insmod utility: The program loads the module code and data into the kernel, which, in turn, performs a function similar to that of ld, in that ...
-2
votes
4answers
319 views

Where is the Linux source kept in a Rackspace Gentoo VPS?

I'm emerging udev and it complains it couldn't find the kernel sources under /usr/src/linux (there's nothing inside /usr/src/ indeed). As a result, it tries to take the version from the currently ...
0
votes
1answer
223 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 ...
2
votes
1answer
212 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 ...
14
votes
2answers
7k views

Linux memory fragmentation

Is there a way to detect memory fragmentation on linux ? This is because on some long running servers I have noticed performance degradation and only after I restart process I see better performance. ...
0
votes
1answer
160 views

Changing MAC address on the Fly on old kernel 2.6.x

I'm doing some research on old kernels and running the following on 2.6.7 or 2.6.8 gives a resource busy error. But on 2.6.28 the command works as expected. How would I determine which kernel allowed ...
22
votes
9answers
17k views

Maximum number of files in one ext3 directory while still getting acceptable performance?

I have an application writing to an ext3 directory which over time has grown to roughly three million files. Needless to say, reading the file listing of this directory is unbearably slow. I don't ...
3
votes
3answers
1k views

Munin “Available entropy” when using address space layout randomization

Having just configured Munin for statistics logging on my gentoo server (hardened profile), I am noticing that my "Available entropy" is consitently in the 200-300 range. This seems way to low, so I ...
0
votes
1answer
912 views

traffic shaping with “netem delay” works ok, but limits upload bandwidth to 330KB/s. Why?

I'm using Ubuntu 9.04 and the kernel 2.6 build-in NETEM tool to delay traffic. After I apply: tc qdisc add dev eth0 root netem delay 100ms The upload bandwidth can't go further than 330KB/s and I ...
5
votes
2answers
342 views

Please explain the following o/p of “top” command

Please explain the following line from the "top" command in the bold :- Mem: 1026228k total, 449640k used, 576588k free, 44812k buffers Swap: 1052248k total, 2020k used, 1050228k ...
1
vote
4answers
377 views

How can Linux run on different microprocessors?

How can Linux run on different microprocessors? Is the Linux kernel being compiled at installation each time?