Saturday, May 29, 2010

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:


Save the file and reboot. Source: