ACPI related Linux kernel parameters

Some hardware types, mainly fairly old or very recent ones, fail to install. In many cases, this might happen because support for this type of hardware is missing from the installation kernel or due to certain functionality included in this kernel, such as ACPI, that still cause problems on some hardware.

There are various other ACPI-related kernel parameters that can be entered at the boot prompt prior to booting for installation:

acpi=off
This parameter disables the complete ACPI subsystem on your computer. This may be useful if your computer cannot handle ACPI at all or if you think ACPI in your computer causes trouble.

acpi=force
Always enable ACPI even if your computer has an old BIOS dated before the year 2000. This parameter also enables ACPI if it is set in addition to acpi=off.

acpi=noirq
Do not use ACPI for IRQ routing.

acpi=ht
Run only enough ACPI to enable hyper-threading.

acpi=strict
Be less tolerant of platforms that are not strictly ACPI specification compliant.

pci=noacpi
Disable PCI IRQ routing of the new ACPI system.

pnpacpi=off
This option is for serial or parallel problems when your BIOS setup contains wrong interrupts or ports.

notsc
Disable the time stamp counter. This option can be used to work around timing problems on your systems. It is a new feature, if you see regressions on your machine, especially time related or even total hangs, this option is worth a try.

nohz=off
Disable the nohz feature. If your machine hangs, this option might help. Generally, you do not need it.

Once you have determined the right parameter combination, you also need to writes them to the boot loader configuration (grub) to make sure that the system boots properly next time.

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How to Temporarily Switch Languages for One Application Only on Linux

To run a single application in another language (that has already been installed), use one of the following commands:

LANG=de_DE application to start any standard X application or GNOME application in German. For other languages, use the appropriate language code. Get a list of all language codes available using the locale -av command.

KDE_LANG=de application to start any KDE application in German. For other languages, use the appropriate language code.

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Performance tuning Linux Kernel with swappiness parameter

The swappiness parameter controls the tendency of the kernel to move processes out of physical memory and onto the swap disk. Because disks are much slower than RAM, this can lead to slower response times for system and applications if processes are too aggressively moved out of memory.

swappiness can have a value of between 0 and 100

swappiness=0 tells the kernel to avoid swapping processes out of physical memory for as long as possible
swappiness=100 tells the kernel to aggressively swap processes out of physical memory and move them to swap cache

The default setting in Linux is swappiness=60. Reducing the default value of swappiness will probably improve overall performance for a typical desktop installation. A value of swappiness=10 is recommended, but feel free to experiment.

To check the swappiness value use command: cat /proc/sys/vm/swappiness

To make a change permanent, edit the configuration file with your favorite editor:

vi /etc/sysctl.conf

and add following parameter to the end of the file like so:

vm.swappiness=10

Save the file and reboot.

Still, there are users who insist that, for example, a system backup should never force OpenOffice out to disk. They don't care how quickly a system maintenance application runs at 3:00 in the morning, but they care a lot about how the system responds when they are at the keyboard. This wish was expressed repeatedly until Andrew Morton exclaimed:

I'm gonna stick my fingers in my ears and sing "la la la" until people tell me "I set swappiness to zero and it didn't do what I wanted it to do.

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How to mount samba share on Linux client

Samba can be used to allow connectivity between Linux and Windows. Samba can be used to share printers, share directories, connect to an windows domain, and many other useful features.

In order to mount your samba share to your Linux client open up the /etc/fstab file and insert the following line into this file

//172.19.12.137/Music /mnt/samba cifs credentials=/etc/accessfile 0 0

Now create a new file: /etc/accessfile with following contents

username=nikesh
password=some_password

Save the above file and restart your Linux client (or type command mount -a), after restart you should now able to access the share content from the samba server under /mnt/samba directory.

This is preferred over having passwords in plaintext in a shared file, such as /etc/fstab. Be sure to protect any credentials file properly and also note that there should not be any extra space in this file.

It there are any space in this credentials file you might get the following error on trying to mount the file system

mount error(13): Permission denied
Refer to the mount.cifs(8) manual page (e.g.man mount.cifs)

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