System Ubuntu 14.04

I want to change my swappiness from the default 60 to 10. According to this answer I need to log in as root and edit /proc/sys/vm/swappiness and add or edit to vm.swappiness = 10

When opening that file as root I only see the number 60 when I add vm.swappiness = 10and try to save I get Error writing /proc/sys/vm/swappiness: Invalid argument

If I simply change 60 to 10 the file saves without issue I check the changes take place with cat /proc/sys/vm/swappiness it shows the changes took place

By editing this file as root I was under the assumption the changes would remain permanent but once I shut down and restart the default is back to 60. Why aren't the changes remaining permanent? What writes the file back to 60 after reboot?

up vote 15 down vote accepted

If you want to set the swapiness without rebooting you could execute the following command:

echo 10 > /proc/sys/vm/swappiness

This will set the swapiness to 10 in this case. You can only echo a number because all this will do is call a kernel function to set the swapiness to 10 and this function only accepts numbers (this explains why you get a invalid argument error: you're trying to write other characters than numbers).

However, this is only temporary. The value will be reset at the next reboot to the default value.

To make the change permanent:

  1. Edit /etc/sysctl.conf as root

    sudo nano /etc/sysctl.conf
  2. Add the following line to the file:

    vm.swappiness = 10
  3. Save the file using CTRL + X

The changes made to sysctl.conf will apply on reboot or you can reload them using sudo sysctl -p (so sudo sysctl -p will have the same effect as echo 10 > /proc/sys/vm/swappiness in this case).

  • Fastest response time ever :) i will try it out and report back.......thanks! – damien May 9 '14 at 9:29
  • worked a treat thanks – damien May 9 '14 at 9:41
  • and to check it cat /proc/sys/vm/swappiness – azerafati May 17 '16 at 13:35

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