Vm.swappiness=1 isn't working!

Technical Issues & Assistance
#1

Hi,

I have 8 GiB of RAM(7.23 usable), and it’s quite good. So, I don’t want the system to use the Swap until it really needs it!

  1. I set the swappiness in /etc/sysctl.d/20-swappiness.conf to 10, then to 5, then to 1, but it didn’t have any effect!
  2. I also tried $sudo sysctl vm.swappiness=1, and I even tried $sudo sysctl vm.swappiness=0 but nothing happened! it still uses Swap even if the ram usage is just 4-6/7.23!

I turned off the swap, then repeated 2), but no effect too!

I’m confused. Why isn’t it working?!

#2

You followed these steps and it didn’t work?

https://wiki.archlinux.org/index.php/Swap#Swappiness

Have you confirmed that it did in fact change with

cat /sys/fs/cgroup/memory/memory.swappiness

or

cat /proc/sys/vm/swappiness

I don’t believe setting it to 0 is a good idea, use 1-100

I have a laptop with 8Gb of RAM and I have the opposite issue, I can’t get the kernel to use the swap without upping the swappiness, funny how that works :stuck_out_tongue:

2 Likes
#3

Yes

I was thinking it might do sth!

ironic :joy:

I read this article and set /proc/sys/vm/vfs_cache_pressure to 40, then swappiness to 4, (I made sure they’re set up using sysctl) and I really was not very sure it had a serious effect on the swap usage :joy:

I turned swap off, then it was 6G usage, turned it on again, then opened a lot of chrome tabs, and it started to be filled when the usage reached 6.45G :3

I’m not sure what’s going on. but I’m sure I didn’t miss anything!

Currently:
sysctl vm.swappiness results in: vm.swappiness = 4
and sysctl vm.vfs_cache_pressure results in: vm.vfs_cache_pressure = 40

what else should I reduce? :joy:

#4

You can always set swappiness to 1, which essentially only uses it when absolutely necessary, note that you’ll need to reboot or swapoff/swapon to make sure swap is cleared. Otherwise can take awhile to notice it take effect.

2 Likes
#5

That’s what I have mine set to on my main pc which has more than enough RAM

1 Like
#6

For the record: I also find that vm.swappiness has absolutely no effect on the swap usage in my Debian stable system, I am convinced it is a placebo knob :expressionless:

@OP: can you drop the caches?

sudo tee /proc/sys/vm/drop_caches <<<"3"

^ That should free up swap space, not really a solution though.

I use zswap, that might help a bit, add this kernel parameter:

zswap.enable=1

It won’t change the swap usage per se but it will apply compression and make if faster and more efficient.

2 Likes
#7

In order to have the swappiness to be in effect without to have to reboot after it s saved in your sysctl file , you have to do this command in your /etc/sysctl.conf file in terminal;

sysctl -p

& check if it s in there afterward.

1 Like
#8

@Head_on_a_Stick , thx , will try that one out, good trick in there.

#9

Same!

1 Like
#10

I did that, but no effect, too

did that but no effect

Ah, I see

#11

Well , weird. What s the output from this in terminal

cat /proc/sys/vm/swappiness

Also , what s the output if you do in terminal

sysctl -p

#12

4
:smiley:
I made it so, because I wanted swap to start working when ~250MB only left in memory, but it starts working when ~800MBs are left

–

vm.swappiness = 4
vm.vfs_cache_pressure = 40
fs.inotify.max_user_watches = 524288
#13

Thx for the comeback, it s in it, it should be working …

Edit: Here are my last 4 output : might help you out.

vm.swappiness = 10
vm.dirty_ratio = 40
vm.dirty_background_ratio = 10
vm.vfs_cache_pressure = 50

1 Like
#14

thanks for sharing, will try these options

1 Like
#15

@ahmedloay, No problem mate.