Ubuntu Swappiness

My desktop has been running slow for a while. Granted I have a PoC computuer with only 4GB of RAM but it should suffice to run Ubuntu. The disk seems to grind a lot which usually indicates a lot of swapping. Since the wife and I use different browsers I have to assume one is swapped out over time. This seems odd since the system monitor shows swap space being used even though I have plenty of RAM left.

Enter the swappiness configurable. Here's a cut and past from the Swap FAQ.

What is swappiness and how do I change it?

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 Ubuntu is swappiness=60. Reducing the default value of swappiness will probably improve overall performance for a typical Ubuntu desktop installation. A value of swappiness=10 is recommended, but feel free to experiment. Note: Ubuntu server installations have different performance requirements to desktop systems, and the default value of 60 is likely more suitable.

To check the swappiness value

cat /proc/sys/vm/swappiness

To change the swappiness value A temporary change (lost on reboot) with a swappiness value of 10 can be made with

sudo sysctl vm.swappiness=10

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

gksudo gedit /etc/sysctl.conf

Search for vm.swappiness and change its value as desired. If vm.swappiness does not exist, add it to the end of the file like so:

vm.swappiness=10

Save the file and reboot.

I'll try a swappiness of 10 and report back here in a few days if performance improves. The instant I changed it the disk stopped grinding so I am hopeful this will fix my problem.