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 troubleshoot high Kernel time?

I have unusually high Kernel time on my CPUs as shown in task manager. What are some ways I can troubleshoot this?
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Still getting aacraid: Host adapter abort request errors after following recommended steps

I am getting the infamous aacraid: Host adapter abort request error with my new Adaptec RAID Controller under high I/O. I have read several forums, even Adaptecs, that setting the /sys/block/sdX/device/timeout value to 45 will fix this. However I…
Jim
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TIME_WAIT consumes file descriptors?

In many TCPIP and Web tunning guide, recommends increasing max number of file descriptors when getting the error "Too many open files" but, i can't see TIME_WAIT in outputs of "lsof -i" Does anyone know that TIME_WAIT consumes file descriptors? or…
sam
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Can I increase inode count in Linux?

I have a Linux MIPS router with 2.4.17 kernel. Root fs is a tmpfs and /rom is a cramfs. There is 4MB free memory and 3MB free on tmpfs. I can create a few new empty files, but the next ones fail with "not enough space". However, I can append 1MB of…
vlad
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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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how to tell if NIC has multiqueue enabled?

Can anyone tell me what command i run to determine if my 10G NIC is running in single RX-TX queue mode or multiqueue? It looks like it only has 1 RX/TX queue according to cat /proc/interrupts root@hostname:scripts]# cat /proc/interrupts | grep…
dobbs
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TCP packet being retransmitted 7 times when sysctl tcp_retries1 is set to 3 - why?

Ubuntu 12.04 I am trying to better understand how many times TCP will attempt to retransmit a packet when it does not receive confirmation the destination received it. After reading the tcp man page it seemed clear this is controlled by the sysctl…
HodB
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Unexpectedly shrunk window

I run a major media upload/download site and I noticed these: Is this serious or background noise due to the big file sizes and is there any tweaks I can add to /etc/sysctl.conf to improve and prevent issues? [8822139.804040] TCP: Peer…
Jason
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How to install packages with APT without user interaction?

I have a script that downloads and replaces kernel headers in Debian squeeze. function fixHeaders(){ #Replace the kernel headers from OVH with standard kernel headers... aptitude -y install linux-image-2.6.32-5-amd64 sed…
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How to force Debian to boot new Kernel?

I'm running Debian 6, Debian GNU/Linux, with Linux 2.6.32-5-amd64 under Grub2 ( 1.98+20100804-14+squeeze1) on a remote system (no possibility to view the pre-boot messages). I compiled and installed a new kernel, but I can not get it to boot. What I…
ThE_-_BliZZarD
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Linux Kernel Versioning: Debian Sid vs Ubuntu Precise

I have setup two machines: On one machine I have installed Ubuntu Precise 12.04 beta and dist-upgraded to the latest packages. On the other machine I have installed Debian Sid Unstable and dist-upgraded to the latest packages. On the Ubuntu machine…
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Monolithic vs Micro kernel

What are the differences between a monolithic kernel and a microkernel with respect to structure and security. My friend told me that Linux systems have monolithic kernel and thus are not easier to hack but I don't think he was actually correct.…
Prasoon Saurav
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kube-proxy won't start in Minikube because of permission denied issue with /proc/sys/net/netfilter/nf_conntrack_max

After updating Arch Linux (sudo pacman -Syu) and restarting the system, Minikube fails to start because of kube-proxy. The logs show it was trying to modify /proc/sys/net/netfilter/nf_conntrack_max but it ran into a permission denied issue. I tried…
RedGiant
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/dev/shm & /proc hardening

I've seen mention of securing /dev/shm and /proc and I was wondering how you do that and what it consists of doing? I assume this involves /etc/sysctl.conf editing of some kind right. Like these? kernel.exec-shield = 1 kernel.randomize_va_space = 1…
Tiffany Walker
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Why OOM-killer invoked even when huge amount of RAM is free

On EC2 ebs-backed xlarge ubuntu instance, oom-killer is getting invoked. From /var/log/syslog output below, it appears that ZONE_NORMAL is running out of memory: Node 0 Normal free:11344kB min:11556kB low:14444kB high:17332kB active_anon:10936284kB…
tarkeshwar
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