There are kernel parameters to customize kernel operation mode. One of them is vm.swappiness.
What value to prefer to minimize page/swap file usage vm.swappiness: 1 or 0?
Rumors and outdated info
The vm.swappiness value of 0 was discussed many times on Internet, including here Swap consumed despite of swappiness=0 - #2 by linux-aarhus. I saw many posts where were mentioned that ‘swapping/paging is disabled by that option, use vm.swappiness = 1’, a numerous posts in opposite vm.swappiness = 0 minimizzes of swap usage.
As note: vm.swappiness = 0 does not turn off swapping/paging feature, but it minimizes swap file usage.
details/evidence (system info terminal outputs)
Let’s try to sync with modern reality:
❯ /usr/bin/free -k
total used free shared buff/cache available
Mem: 65489500 4317952 571268 1337692 60600280 59052612
Swap: 524284 268 524016
❯ /usr/bin/free -g
total used free shared buff/cache available
Mem: 62 4 0 1 57 56
Swap: 0 0 0
❯ uname -r
6.2.0-1-MANJARO
❯ pacman -Qi linux62 | grep Ver
Version : 6.2.0rc3-1
❯ sudo sysctl -a | grep swap
vm.swappiness = 0
❯ cat /proc/sys/vm/swappiness
0
❯ uptime
10:42:01 up 11:33, 4 users, load average: 0.66, 0.75, 0.81
❯ uptime -p
up 11 hours, 34 minutes
❯ swapon -a -v
swapon: /swap/swapfile: already active -- ignored
❯ cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a device; this may
# be used with UUID= as a more robust way to name devices that works even if
# disks are added and removed. See fstab(5).
#
# <file system> <mount point> <type> <options> <dump> <pass>
UUID=261E-4AE1 /boot/efi vfat umask=0077 0 2
/dev/mapper/luks-4620125f-31e5-4d3a-ac65-3104599474aa / btrfs subvol=/@,defaults,discard=async,ssd 0 0
/dev/mapper/luks-4620125f-31e5-4d3a-ac65-3104599474aa /home btrfs subvol=/@home,defaults,discard=async,ssd 0 0
/dev/mapper/luks-4620125f-31e5-4d3a-ac65-3104599474aa /var/cache btrfs subvol=/@cache,defaults,discard=async,ssd 0 0
/dev/mapper/luks-4620125f-31e5-4d3a-ac65-3104599474aa /var/log btrfs subvol=/@log,defaults,discard=async,ssd 0 0
/dev/mapper/luks-4620125f-31e5-4d3a-ac65-3104599474aa /swap btrfs subvol=/@swap,defaults,discard=async,ssd 0 0
/swap/swapfile swap swap defaults,noatime 0 0
tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0
❯ cat /proc/meminfo
MemTotal: 65489500 kB
MemFree: 539940 kB
MemAvailable: 58862516 kB
Buffers: 784 kB
Cached: 60213944 kB
SwapCached: 0 kB
Active: 49295456 kB
Inactive: 14509960 kB
Active(anon): 3657472 kB
Inactive(anon): 1339308 kB
Active(file): 45637984 kB
Inactive(file): 13170652 kB
Unevictable: 456424 kB
Mlocked: 0 kB
SwapTotal: 524284 kB
SwapFree: 524016 kB
Zswap: 160 kB
Zswapped: 256 kB
Dirty: 1076 kB
Writeback: 0 kB
AnonPages: 3970888 kB
Mapped: 35083436 kB
Shmem: 1406092 kB
KReclaimable: 226376 kB
Slab: 352904 kB
SReclaimable: 226376 kB
SUnreclaim: 126528 kB
KernelStack: 16512 kB
PageTables: 135996 kB
SecPageTables: 0 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 33269032 kB
Committed_AS: 16350036 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 56168 kB
VmallocChunk: 0 kB
Percpu: 2608 kB
HardwareCorrupted: 0 kB
AnonHugePages: 593920 kB
ShmemHugePages: 821248 kB
ShmemPmdMapped: 0 kB
FileHugePages: 96256 kB
FilePmdMapped: 94208 kB
CmaTotal: 0 kB
CmaFree: 0 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
Hugetlb: 0 kB
DirectMap4k: 299780 kB
DirectMap2M: 17160192 kB
DirectMap1G: 49283072 kB
❯ neofetch
██████████████████ ████████ m@pc
██████████████████ ████████ ----
██████████████████ ████████ OS: Manjaro Linux x86_64
██████████████████ ████████ Kernel: 6.2.0-1-MANJARO
████████ ████████ Uptime: 11 hours, 49 mins
████████ ████████ ████████ Packages: 1095 (pacman)
████████ ████████ ████████ Shell: bash 5.1.16
████████ ████████ ████████ Resolution: 1920x1080
████████ ████████ ████████ DE: Plasma 5.26.5
████████ ████████ ████████ WM: KWin
████████ ████████ ████████ Theme: [Plasma], Breeze [GTK2/3]
████████ ████████ ████████ Icons: [Plasma], breeze-dark [GTK2/3]
████████ ████████ ████████ Terminal: konsole
████████ ████████ ████████ Terminal Font: Hack 11
CPU: 11th Gen Intel i7-1195G7 (4) @ 2.900GHz
GPU: Intel TigerLake-LP GT2 [Iris Xe Graphics]
Memory: 5873MiB / 63954MiB
❯ date
Mon 16 Jan 11:01:01 MSK 2023
❯ pacman-mirrors --get-branch
unstable
So at least current behavior is not 'swapping/paging '.
PS
I use default vm.vfs_cache_pressure value:
❯ sudo sysctl -a | grep "vm.vfs_cache_pressure"
vm.vfs_cache_pressure = 100
❯ cat /proc/sys/vm/vfs_cache_pressure
100
One of points of this topic could be:
if you want to minimize swapping threshold setup the vm.swappiness parameter as 0 value, not as 1.
How to setup the kernel parameter: Swap - ArchWiki
16-Jan-2023,
swapping feature used as swap to file,
Linux kernel 6.2-RC3 (newest on the moment of that posting),
Manjaro Linux (KDE),
unstable branch of updates.
