Swappiness

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Swappiness is a Linux kernel parameter that controls the relative weight given to swapping out runtime memory, as opposed to dropping pages from the system page cache. Swappiness can be set to values between 0 and 100 inclusive. A low value causes the kernel to avoid swapping, a higher value causes the kernel to try to use swap space. The default value is 60, and for most desktop systems, setting it to 100 may affect the overall performance, whereas setting it lower (even 0) may decrease response latency.[1]

Value Strategy
vm.swappiness = 0 Version 3.5 and over: disables swapping[2]

Prior to version 3.5: The kernel will swap only to avoid an out of memory condition.

vm.swappiness = 1 Version 3.5 and over: Minimum swappiness without disabling it entirely
vm.swappiness = 60 The default value.
vm.swappiness = 100 The kernel will swap aggressively.

To temporarily set the swappiness in Linux, write the desired value (e.g. 10) to /proc/sys/vm/swappiness using the following command, running as root user:

# Set the swappiness value as root
echo 10 > /proc/sys/vm/swappiness
 
# Alternatively, run this as a non-root user
sudo sysctl -w vm.swappiness=10
 
# Verify the change
cat /proc/sys/vm/swappiness
10
 
# Alternatively, verify the change
sysctl vm.swappiness
vm.swappiness = 10

Permanent changes are made in /etc/sysctl.conf via the following configuration line (inserted, if not present):

vm.swappiness = 10

References[edit]

  1. ^ "Linux: Tuning Swappiness". kerneltrap.org. 2004-04-29. Retrieved 2013-12-27. 
  2. ^ "OOM relation to vm.swappiness=0 in new kernel". 

External links[edit]