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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 does /proc/net/tcp6 represents ::1 as ::100:0

I was writing an utility to check /proc/net/tcp and tcp6 for active connections as its faster than parsing netstat output. As I dont actually have ipv6 enabled I was mainly utilizing localhost as my reference point. Here is a copy of my…
gregswift
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1000 HZ linux kernel necessary if I have tickless and high resolution timer?

I am trying to improve performance on my server. I have a few processes that need low jitter (less than 10ms variance). I have a load average of 4 maximum on an i7-920 (4 physical cores, 8 with HT). There are about 10 processes ranging from 40% to…
Bob
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Can't update linux kernel on VPS

I recently started using VPS from OVH: http://www.ovh.co.uk/vps/vps-classic.xml This is likely problem very specific to this one provider. My goal is to install and run Docker on it, for this I need kernel supporting modules. By default, OVH's VPS…
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tc u32 --- how to match L2 protocols in recent kernels?

I have a nice shaper, with hashed filtering, built at a linux bridge. In short, br0 connects external and internal physical interfaces, VLAN tagged packets are bridged "transparently" (I mean, no VLAN interfaces are there). Now, different kernels do…
brownian
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How to properly permanent enable ip forwarding in Linux with systemd?

I try to enable ip forwarding (between enp0s3 and tun0 interfaces) and write net.ipv4.ip_forward = 1 in /etc/sysctl.conf. After restart I have $ cat /proc/sys/net/ipv4/ip_forward 1 But forwarding still not working. I try to add…
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is /dev/dm-1 a partition or a whole block device?

Is there a way to figure out if /dev/dm-1 is a block device partition or a whole block device? If /dev/dm-1 is a partition, is there a way to find out the path to the corresponding whole block device?
Loic Dachary
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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 anyone tell me what the Linux utility mdev does? It…
user626201
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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 appeared to be a kernel panic hang. I rebooted the…
Low Kian Seong
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How to achieve per-packet multipath routing on Linux?

Linux Kernel before 3.6 used route caching to do IPv4 multipath routing, which meant routing between two separate lines/ISPs was quite easy. From 3.6 the algorithm changed to being per-packet, meaning that some route table/rule/iptables marker…
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View full program command line arguments in OOM killer logs

Is it possible to view full program command line arguments in OOM killler logs ? What I see now in /var/log/syslog is Memory cgroup out of memory: Kill process 29187 (beam.smp) score 998 or sacrifice child Killed process 29302 (cpu_sup)…
sergeyz
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nic: Something Wicked happened! ffff

I'm configuring a GNU/Linux Router with Debian Stretch (9.7) and before rebooting the server, all traffic from one interface to another was going ok, but after that, I received a message like this (tty): enp1s6: Something Wicked happened! ffff. I…
ivanleoncz
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Why does Linux answer to ARP on incorrect interfaces?

I have the following Linux networking setup: there is an eth10 network interface with the assigned address 10.11.0.1/24. Then there is a tap0 network interface with assigned dummy address 0.0.0.1/32 (I assigned a dummy address to bring the interface…
juhist
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Why can't QEMU allocate the memory if the Linux caches are too big?

If I use my machine [Ubuntu 16.04 64 bit, kernel 4.4] for a while, QEMU needs the kernel caches to be dropped, otherwise, it won't manage to allocate the RAM. Why does it happen? This is a sample run: ~$ free -m total used …
Marcus
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Default value of /proc/sys/fs/file-max

I am aware that /proc/sys/fs/file-max defines the maximum number of open file descriptors and can be set on runtime or during boot. However: what is its default value? Checking 10 servers in my company gives me 7 different values, which all seem…
taranion
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Linux: Why does the CPU frequency fluctuate when using the performance governor?

I'm using a Debian 8 amd64 machine for benchmarking. During experimentation, I would like the CPU to operate at a fixed frequency (preferably the maximum possible). This will rule out the CPU clock speed as a source of variation in the…
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