Separation Anxiety: A Tutorial for Isolating Your System with Linux Namespaces

2017-02-06 18 min read GuestPost Linux Vurtualization
With the advent of tools like Docker, Linux Containers, and others, it has become super easy to isolate Linux processes into their own little system environments. This makes it possible to run a whole range of applications on a single real Linux machine and ensure no two of them can interfere with each other, without having to resort to using virtual machines. These tools have been a huge boon to PaaS providers. Continue reading

journalctl command to see kernel messages

2017-01-30 1 min read Fedora
Sometimes, there are just too many messages in journalctl output and it becomes a mystery game to search for the messages you are looking for. But luckily you do not need to use grep to find the right message. Here is example of what I had to do when I was looking for kernel messages. journalctl _TRANSPORT=kernel # To see all the fields, you can use the verbose mode journalctl _TRANSPORT=kernel -o verbose # And the filter on priority if needed to get the messages you need journalctl _TRANSPORT=kernel PRIORITY=4 # and follow journalctl _TRANSPORT=kernel PRIORITY=4 -f -l

ionice – renice you IO activity for the process.

2015-04-13 1 min read Learning
ionice is utility provided by the package util-linux. Description of util-linux: Description : The util-linux package contains a large variety of low-level system utilities that are necessary for a Linux system to function. Among others, Util-linux contains the fdisk configuration tool and the login program. With the help of this utility, you can set the scheduler priority for your IO scheduling upto RealTime, but be careful that can make other process sluggish. Continue reading

zswap – compcache, compressed swap for better performance

2013-11-17 2 min read Linux
First, here is a link to article on compcache. http://code.google.com/p/compcache/wiki/CompilingAndUsingNew zswap is already in the kernel and you can see the documentation in the kernel documentation. Here is the name of the file if you need: /usr/share/doc/kernel-doc-$(uname -r)/Documentation/vm/zswap.txt Here is the overview, in case you do not want to install kernel-doc Overview: Zswap is a lightweight compressed cache for swap pages. It takes pages that are in the process of being swapped out and attempts to compress them into a Continue reading

Kernel ata exception — found workaround.

2010-07-20 2 min read Fedora Linux
I have been getting the below errors in my system for quite sometime now, I think since F9 or before that. The offending hardware is CD drive. I looked all around the net for a solution but did not find anything. Will keep looking to solve the problem. I found various solutions being suggested like adding noirq or nobiosirq or noacpi and such. None of this helped. So for now I am happy with turning off the haldaemon as soon as the system comes up. Continue reading

Are you swapped? Increase the performance of Linux machine.

2010-07-14 2 min read Fedora Linux
With the ever increasing cost of the Hardware, the amount of physical RAM available on the system is increasing day by day. For example, couple of years back, I had a system which was very high end Desktop with 256MB RAM and today I have a 2GB RAM Desktop. So, whats the point. The Linux systems (right word should be kernel) are desiged to use both RAM and swap partition. Continue reading

Getting the list of IOCTLS in the kernel.

2010-06-25 1 min read Linux
Sometime back I was helping one of my friends in looking for all the IOCTLs supported by the kernel. Well we did not find the info we were looking for and thus thought to write a perl script to get all the IOCTLS supported by the kernel. Here it is, simple script to scan through the code and give you a list: #!/usr/bin/perl — @files = `grep -r ” _IO” /usr/src/redhat/SOURCES/linux-2. Continue reading
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