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Questions tagged [linux-kernel]

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.

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.

The Linux kernel is released under the GNU General Public License version 2 (GPLv2) (plus some firmware images with various non-free licenses[citation needed]), and is developed by contributors worldwide. Day-to-day development discussions take place on the Linux kernel mailing list.

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Why some tcp_[rw]?mem$ voodoo show all equal values?

Looking at TCP optimization guides across the Internet, a common theme is setting the tcp_mem, tcp_rmem, or tcp_wmem three-integer vector to have equal values in the sysctl.conf file. Borrowing from the TCP man page, the function of the values are…
Robert
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Server won't boot, kernel panic - not syncing

After a reboot of a CentOS 6.2 server we are getting a kernel panic with the following error: Kernel panic - not syncing: Attempted to kill init! Panic occurred, switching back to text console When passing init=option selinux=0 to the kernel at…
Tbuermann
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"show_signal_msg: N callbacks suppressed" then pegged at 100% and machine unresponsive

This happened on an Ubuntu 14.04 64-bit DigitalOcean Droplet: Apr 22 02:17:02 localhost CRON[32514]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Apr 22 03:16:59 localhost kernel: [211877.884132] show_signal_msg: 12 callbacks…
Catalin P
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How can I make my own linux distro?

My question is bit off-topic or may be impractical. The thing is, on the web too many material available to download customized linux distro. But what if I want to make my own linux distro ? Lets say I have downloaded linux kernel, gnome dekstop,…
Aditya
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What signal is being sent to an EC2 Instance on shut down?

When you terminate an instance-store pv instance through the AWS console or the API, what "signal" does it receive so it knows it has to gracefully shut down? First guess would be ACPI, but on boot Linux reports ACPI in unprivileged domain…
Axel Fontaine
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__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 only thing using any significant system resources…
righdforsa
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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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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). Enable clocksource failover by adding…
Sidd
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Linux Kernel setup: is it good idea to enable everything in Cryptographic API?

There are several implementations for some algorithms, which use CPU instructions which may or may not be available on current system. Is it good idea to just enable (in kernel, not as modules) all of them - i.e. is fastest implementation available…
Powerman
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What are Linux shared memory 'segments' vs. 'pages'?

The Linux kernel docs say: shmall: This parameter sets the total amount of shared memory pages that can be used system wide. Hence, SHMALL should always be at least ceil(shmmax/PAGE_SIZE). But I can't find a definition for page. shmmax, for…
Dogweather
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How to force logging all terminal actions on Ubuntu 12.04 server?

I believe my server has just got compromised interactively. As this server will go to thrash anyway, I wonder if I can get a better insight of what the villain is doing by forcing logging of all tty. Years ago I've seen a kernel patch, that does…
Adam Ryczkowski
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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 not dedicated to us but is used by other customers…
Janning
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High CPU usage in random IP/Port UDP DDoS

I have been getting these UDP floods with random IPs and ports. randomip:randomport -> myip:randomport 0 byte payload For some reason it is using a lot of CPU. Here is the results of perf top -e cycles:k. Is there any way to optimize the…
bob
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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: Log level INFO requires LOG Target in your kernel…
user186639
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/var/log/messages showing lots of CE Err=0x2000 even on unused banks (slots)

I recently had to upgrade an old server (HP ML350G5) with used FBDIMM DDR2 RAM (could not get new ones where I live). After rebooting /var/log/messages has been plagued with CE Err=0x2000 errors but system appears to be stable. I'm guessing ECC is…
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