swappiness

You can use this parameter to tune a container's memory swappiness behavior. A swappiness value of 0 causes swapping to not occur unless absolutely necessary. A swappiness value of 100 causes pages to be swapped aggressively. Valid values are whole numbers between 0 and 100 . If the swappiness parameter isn't specified, a default value of 60 is used. If a value isn't specified for maxSwap , then this parameter is ignored. If maxSwap is set to 0, the container doesn't use swap. This parameter maps to the --memory-swappiness option to docker run . Consider the following when you use a per-container swap configuration.

• Swap space must be enabled and allocated on the container instance for the containers to use.

By default, the Amazon ECS optimized AMIs don't have swap enabled. You must enable swap on the instance to use this feature. For more information, see Instance store swap volumes in the Amazon EC2 User Guide for Linux Instances or How do I allocate memory to work as swap space in an Amazon EC2 instance by using a swap file?

• The swap space parameters are only supported for job definitions using EC2 resources.

• If the maxSwap and swappiness parameters are omitted from a job definition, each container has a default swappiness value of 60. Moreover, the total swap usage is limited to two times the memory reservation of the container.

This parameter isn't applicable to jobs that are running on Fargate resources. Don't provide it for these jobs.