Questions tagged [kernel]

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 components).

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 components).

Usually as a basic component of an operating system, a kernel can provide the lowest-level abstraction layer for the resources (especially processors and I/O devices) that application software must control to perform its function. It typically makes these facilities available to application processes through inter-process communication mechanisms and system calls.

Operating system tasks are done differently by different kernels, depending on their design and implementation. While monolithic kernels execute all the operating system code in the same address space to increase the performance of the system, microkernels run most of the operating system services in user space as servers, aiming to improve maintainability and modularity of the operating system.

Source: wikipedia

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How can I take advantage of IW10 in kernel 2.6.33?

I've read that 2.6.33+ allows setting custom cwnd. if the IW is 10 by default (for all distros? only some?) how does one view what the current IW is on a particular compiled…
John Bachir
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How do i view / enable kernel logs on centos / red hat linux?

Possible Duplicate: How do i view / enable kernel logs on an ec2 instance (amazon linux)? I've got a centos server that i'm playing around with TCP settings in the sysctl.conf to increase the number of concurrent TCP connections it can handle,…
Chris
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How does Linux determine the SCSI address of a disk?

Greetings, I'm working with RHEL 5.5 guest VMs under VMware ESX 4. When I configure the virtual disks in the VM hardware settings, each disk has a SCSI address in the format "N:M". For example, "1:3" would mean SCSI host number 1 and SCSI target ID…
Chris Sears
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Why is MemAvailable a lot less than MemFree+Buffers+Cached?

I'm running a Linux workstation without swap and I have installed earlyoom daemon to automatically kill some processes if I'm running out of RAM. The earlyoom works by monitoring kernel MemAvailable value and if the available memory gets low enough,…
Mikko Rantalainen
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CentOS 6.5 new Kernel not active after reboot

Today I was running some yum updates and wanted to verify that everything went through fine by making sure I had a new kernel. To my surprise I noticed that CentOS was still running 2.6.32-431.5.1.el6.x86_64 even though it looked as though…
Kristofer
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Optimal kernel configuration and patches for KVM host

I have a server (single socket Nehalem w/ 24GB RAM) acting primarily as a KVM host containing a bunch of Windows Servers and a few (tickless) Linux instances. I usually compile my desktop kernels preemptible with 1000 Hz tickless timer, using the…
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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 detailing kernel page allocation failures. What…
ewwhite
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How to Minimize Linux Server Reboots

Last week there were a fair few comments on a slashdot article about whether Unix (or Linux) machines ever need to be rebooted. More than a few of the commenters mentioned having machines with uptimes of several years. As I understand it, linux…
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VFS: file-max limit 1231582 reached

I'm running a Linux 2.6.36 kernel, and I'm seeing some random errors. Things like ls: error while loading shared libraries: libpthread.so.0: cannot open shared object file: Error 23 Yes, my system can't consistently run an 'ls' command. :( I note…
Rick Koshi
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Server freezes without kernel panic

We are running a KVM node which is crashing irregularly showing a very strange behaviour. The interesting thing is that we already had this problem with another node which crashed every 1-2 weeks. As we could not find a hardware issue, we began to…
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How to auto-start Degraded Software RAID1 under Debian 8.0.0 on boot?

If you remove a component HDD from an array, it drops into a "busy box" shell under "(initramfs)" saying something similar to "cannot mount root device" as the RAID1 array becomes "inactive". It is possible to start it using: (initramfs): mdadm…
Bob
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RHEL6 Keeping 1 old kernel and security

I have my RHEL 5&6 servers set to keep 1 old kernel after updates, I do this in case I need to recover the system for any number of reasons. My question is related to security of the system when running with the most current kernel but still having…
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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 on tweaking the Kernel for better TCP performance…
WifiGhost
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Linux Kernel lowmem usage

I am debugging an issue where we are running out of kernel low memory and I am trying to identify who is using the kernel low memory thats contributing to the problem. Following is the meminfo output: MemTotal: 16622556 kB MemFree: …
Sreeni
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Linux arp cache timeout values

I'm trying to configure sane values for the Linux kernel arp cache timeout, but I can't find a detailed explanation as to how they work anywhere. Even the kernel.org documentation doesn't give a good explanation, I can only find recommended values…
Jak
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