[SOLVED] How can I force swappiness=0

[Badkey]

Dear all,

After reboot I have to set the setting again How do I force now swappeing ?

https://blog.lbdg.me/proxmox-best-performance-disable-swappiness/

Regards John

 

[Dunuin]

As far as I know swappiness=0 isn't supported anymore. If you don't want swapping at all, why don't you just remove your swap partition (open /etc/fstab and comment out the line that mounts your swap partition)? If you don't want to reboot you can also run swapoff -a to temporarily disable swapping.

 

[gretz]

To make it persistent you need to add the following line to /etc/sysctl.conf :
vm.swappiness=0

 

[Badkey]

Thanks !!!! /etc/sysctl.conf did it.

 

[Dunuin]

From the kernel documentation:

This control is used to define the rough relative IO cost of swapping and filesystem paging, as a value between 0 and 200. At 100, the VM assumes equal IO cost and will thus apply memory pressure to the page cache and swap-backed pages equally; lower values signify more expensive swap IO, higher values indicates cheaper.
...
At 0, the kernel will not initiate swap until the amount of free and file-backed pages is less than the high watermark in a zone.

So "swappiness=0" won't disable swap, it will just swap out very late. If you want the OOM to kill processes instead of swapping out RAM you really need to disable swap by swapoff -a or unmounting the swap device/file.

 

[Emilien]

I didn't get the motivation to disable swap...

 

[KSpur]

I didn't get the motivation to disable swap...

A case could be creating a Kubernetes node.

If anyone else ends up here looking to disable swap to create a Kubernetes node template...

As far as I know swappiness=0 isn't supported anymore. If you don't want swapping at all, why don't you just remove your swap partition (open /etc/fstab and comment out the line that mounts your swap partition)? If you don't want to reboot you can also run swapoff -a to temporarily disable swapping.

As Dunuin comments ^, the commenting out of the swap partition line in /etc/fstab seems to also be necessary.

 

[glassman]

A case could be creating a Kubernetes node.

If anyone else ends up here looking to disable swap to create a Kubernetes node template...



As Dunuin comments ^, the commenting out of the swap partition line in /etc/fstab seems to also be necessary.

Doesn't kubernetes support swap now?

 

[johnsturgeon]

Quick follow up question to all this, after disabling swap, do I need to re-configure any of my lxcs swap settings? Or is it OK to just leave them thinking they have swap?

 

[LnxBil]

Quick follow up question to all this, after disabling swap, do I need to re-configure any of my lxcs swap settings? Or is it OK to just leave them thinking they have swap?

Have you checked if they see the 0 swap? If they see it, the settings swap cannot be used.

Why do you want to disable swap?

 

[johnsturgeon]

I have checked, and they indeed use zero swap!