(Solved)Swap barely being used even when low off ram

TheLinuxUser · 2018-06-16 10:08:01

Hello everybody I am writing to ask how to make it so that swap would be used more aggressively? At the moment it is barely being used even when ram is full

free -m example output under heavy ram usage.
total used free shared buff/cache available
Mem: 3947 3702 112 22 132 50
Swap: 3999 44 3955

So far I have tried to
1.Manually running swapoff and and swapon on swap partition.
2.Using zram instead of swap partition.
3.Updating kernel.
4.setting vm.swappiness =100
5.Looking for solutions on google and checking out wiki https://wiki.archlinux.org/index.php/swap
but nothing helped.

Last edited by TheLinuxUser (2018-06-19 11:56:09)

seth · 2018-06-16 13:34:52

Why do you believe preferring SWAP over RAM is remotely close to a sane approach?

Read https://bbs.archlinux.org/viewtopic.php?id=231265 for a discussion on swap, oom killing and the meaning of life…

kokoko3k · 2018-06-16 17:11:49

Well, it depends...
You have very little buffered/cached data, so probably file access will be slow, taken.

But since when the data/code you'd prefer to be in the swap area is staying in ram instead? Are you "using" it? Why do you really want it to stay in the swap instead of the ram?
Do you have some memory pages locked there, maybe?
Did you tweaked other /proc/sys/vm settings?
Is that a test case or real usage?
Linux is pretty good in that from my experience.
Here, even with swappiness=0, with16GB of ram, 2 of which currently used and a peak of 4GB, it is using 12MB of swap space, uptime is about one week though.

Last edited by kokoko3k (2018-06-16 17:34:44)

TheLinuxUser · 2018-06-17 11:43:50

I want swap to be used to avoid freezing when running low off ram.I don't know for how long do I have this issue(probably for a while) but its arch linux specific problem.I made a small test with tmpfs I tried to fill it to test swap consumption.
On arch linux it simply freezed after running out off ram while swap was barely used
However on other distro(debian) swap is working fine I can easily reach 1.5 gb swap usage on same test while on arch its just some megabytes.
I was just wondering how to make swap on arch linux to be used more aggressively
in systemctl.d config directory the only change I made is vm.swappiness =100

seth · 2018-06-17 12:32:00

lmg: lvm?

TheLinuxUser · 2018-06-17 13:52:18

I don't use lvm or encryption

Last edited by TheLinuxUser (2018-06-17 13:52:36)

seth · 2018-06-17 15:58:14

Does the problem only apply to your artificial test on tmpfs?
Is it the same swap device (or maybe a partition vs. a file)?
Did you try the LTS kernel?

How do you define "freeze"? Is this in some desktop environment? What if you try this on the multi-user.target (console *only*)?

vm.swappiness does not make swapping more "agressive" but controls what to do when you get short on RAM (swap anon pages or drop file caches) - the swap will not be used when you've plenty of RAM left. The kernel maintains a minimum of free memory to do its job and that should suffice (while apparently does not when LVM mapping is required)

Filling tmpfs will load the inactive anon pages - this is not used, but neither droppable memory, so this will get swapped out and it will be the swapping act that slows down the system (for what reason ever)

TheLinuxUser · 2018-06-17 19:36:52

Not sure how but swap started working again and now it works properly I no longer get complete freeze when running low of ram.Thanks for the help.

Arch Linux

#1 2018-06-16 10:08:01

(Solved)Swap barely being used even when low off ram

#2 2018-06-16 13:34:52

Re: (Solved)Swap barely being used even when low off ram

#3 2018-06-16 17:11:49

Re: (Solved)Swap barely being used even when low off ram

#4 2018-06-17 11:43:50

Re: (Solved)Swap barely being used even when low off ram

#5 2018-06-17 12:32:00

Re: (Solved)Swap barely being used even when low off ram

#6 2018-06-17 13:52:18

Re: (Solved)Swap barely being used even when low off ram

#7 2018-06-17 15:58:14

Re: (Solved)Swap barely being used even when low off ram

#8 2018-06-17 19:36:52

Re: (Solved)Swap barely being used even when low off ram

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