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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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What is required to activate cgroups in Linux

I have a Debian squeeze kernel (linux-image-2.6.32-5-openvz-amd64) which according to the Doku should support cgroups. When I look into the kernel configuration, it does (or is some other kernel configuration required?) # zgrep -i cgroup…
divB
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Limit the number of max threads used by a process in linux kernel

I think I have found something that I need from the Linux kernel that is not currently implemented. I need a way to set a max thread limit per process. Is this possible?
cat pants
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why is kswapd using high CPU on an idle system?

I have an idle Linux centOS system and yet kswapd is using 100% cpu. All I have running is a single bash session with top running.... I have 32G RAM and yet kswapd is constantly using 100% cpu for over 4 hours.
Deshawn
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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 8:45pm tonight, Postgres went down. I logged into the…
Dan Loewenherz
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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 the I/O performance. To try and narrow down the…
Patrick LeBoutillier
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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 1000, an ACK should be delayed by a minimum of 40…
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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 free, 189092k cached Thanks Arpit
Arpit
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Swap Memory Anomoly

I am currently experiencing a memory issue on my centos 7.6 distro. It began with my system swapping even though up to 80GB ram should have been available. free -m total used free shared buff/cache …
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How to dump the kernel stack trace of a failed system call?

This is a canonical question. I want to understand why a specific system call is failing. Is it possible to display the kernel stack trace of the syscall: when the return is non-zero or is negative (it depends on syscall to know when it fails,…
Mircea Vutcovici
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CPU utilization impact due to granularity kernel parameter RHEL6 vs RHEL7

Following kernel parameters are showing very different behaviour from R6 to R7 and we are not able to figure out why. Any help appreciated. kernel.sched_min_granularity_ns kernel.sched_wakeup_granularity_ns Background : Application already running…
Chota Bheem
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Where to get newer RHEL 7 kernel mentioned on bugzilla.redhat.com (for CentOS)

I am using Centos 7.4 and have encountered a bug, which I found a solution for: https://bugzilla.redhat.com/show_bug.cgi?id=1502601 The problem is, solution mentions that bug is fixed in kernel-3.10.0-832.el7 and my CentOS 7.4 has kernel-3.10.0-693…
Pavel
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How to prevent useless kernel-modules from loading?

Our Ubuntu-servers all seem to have various unused kernel-modules loaded wasting RAM and, in the case of jfs for example, running a bunch of useless processes (jfsCommit). I can use rmmod to get rid of them at runtime, but I wonder, what causes them…
Mikhail T.
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GRUB_DEFAULT seems to be ineffectual when trying to boot a custom kernel by ID on Debian 8

I've built a custom kernel on a Debian 8 machine, and I want to set it as the default. A seemingly simple task, but I can't get it to work for the life of me. I built my kernel using the official source code (via git), not using the vendor tarball…
Edd Barrett
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Turning off HyperThread by BIOS or kernel?

Is there any performance difference between these disabled HyperThread scenarios? Which is the best, and why? Disable HT in BIOS Use noht kernel parameter The high-optimized parallel applications works slower with enabled…
andras.tim
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Large percentage of identical systems hang on soft reboot

Reaching out for any other ideas after banging my head against this problem for a week. We have approximately 100 identical systems using the AAEON PICO-ITX BT01 motherboard with J1900 Celeron processor. Every system runs on Debian Jessie with…
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