[Bug 2064483] Re: Ubuntu 24.04 doesn't respect vm.swappiness

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: linux (Ubuntu)
Status: New => Confirmed

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https://bugs.launchpad.net/bugs/2064483

Title:
Ubuntu 24.04 doesn't respect vm.swappiness

Status in linux package in Ubuntu:
Confirmed
Status in linux source package in Noble:
Confirmed

Bug description:
My sysctl vm.swappiness returns vm.swappiness = 180.

Swap kicked in when RAM is filled around 95%. I'm using zRAM as the
swap.

When this happened, my laptop is barely usable, as the system would
have to do both the swap and compression at the same time. If
`vm.swappiness = 180` worked as intended, the issue wouldn't have
happened, as the swap would kick in early, which is good for zRAM
system like mine, see kernel docs: https://docs.kernel.org/admin-
guide/sysctl/vm.html#swappiness

This is my main workstation (laptop). I used to run openSUSE
Tumbleweed on it (~2 years). The experience with `vm.swappiness` is
totally different.

---

Here's my zRAM script:

```
#!/bin/bash

mem_total_kb=$(grep MemTotal /proc/meminfo | grep -E --only-matching '[[:digit:]]+')
mem_total=$((mem_total_kb * 1536))

modprobe zram

echo zstd > /sys/block/zram0/comp_algorithm;
echo $mem_total > /sys/block/zram0/disksize

mkswap /dev/zram0

swapon -p 100 /dev/zram0

```

Here's the content of my /etc/sysctl.conf

```
vm.swappiness=180
vm.page-cluster=0
vm.watermark_scaling_factor=125
vm.watermark_boost_factor=0
```

I make a fresh install, not upgrading from the previous release.

I also upload the screen recording of this issue on my personal Proton
drive here:

https://drive.proton.me/urls/5KTCS1DF58#qZTscuv5XE0M

I mount ~/ramtest in the RAM, then copy the system's usr folder to ~/ramtest. Since most contents in usr are compressible, it should be perfect to show this issue.
---
ProblemType: Bug
ApportVersion: 2.28.1-0ubuntu2
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/seq: archerallstars 4444 F.... pipewire
/dev/snd/controlC0: archerallstars 4448 F.... wireplumber
CRDA: N/A
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
DistroRelease: Ubuntu 24.04
InstallationDate: Installed on 2024-04-27 (5 days ago)
InstallationMedia: Ubuntu 24.04 LTS "Noble Numbat" - Release amd64 (20240424)
MachineType: Acer Swift SF514-52T
NonfreeKernelModules: zfs
Package: linux (not installed)
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/BOOT/ubuntu_o799y4@/vmlinuz-6.8.0-31-generic root=ZFS=rpool/ROOT/ubuntu_o799y4 ro quiet splash vt.handoff=1
ProcVersionSignature: Ubuntu 6.8.0-31.31-generic 6.8.1
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
linux-restricted-modules-6.8.0-31-generic N/A
linux-backports-modules-6.8.0-31-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2
Tags: noble wayland-session
Uname: Linux 6.8.0-31-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip libvirt lpadmin plugdev sudo users
_MarkForUpload: True
dmi.bios.date: 11/26/2018
dmi.bios.release: 1.11
dmi.bios.vendor: Insyde Corp.
dmi.bios.version: V1.11
dmi.board.name: Carlsberg_KL
dmi.board.vendor: KBL
dmi.board.version: V1.11
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: V1.11
dmi.ec.firmware.release: 1.5
dmi.modalias: dmi:bvnInsydeCorp.:bvrV1.11:bd11/26/2018:br1.11:efr1.5:svnAcer:pnSwiftSF514-52T:pvrV1.11:rvnKBL:rnCarlsberg_KL:rvrV1.11:cvnAcer:ct10:cvrV1.11:sku0000000000000000:
dmi.product.family: Swift 5
dmi.product.name: Swift SF514-52T
dmi.product.sku: 0000000000000000
dmi.product.version: V1.11
dmi.sys.vendor: Acer
modified.conffile..etc.default.apport:
# set this to 0 to disable apport, or to 1 to enable it
# you can temporarily override this with
# sudo service apport start force_start=1
enabled=0
mtime.conffile..etc.default.apport: 2024-04-27T05:52:33.862578

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