!! Linux (suse leap ) でswap の追加
(メモ) 

 ## ONE Partition DRIVE ( /root > 100G )
 cd /SSS
 ####  
 # swapon /SSS/file00.swap
 # 
 # mkswap: /SSS/file00.swap: warning: wiping old swap signature.
 # Setting up swapspace version 1, size = 2 GiB (2147479552 bytes)
 # no label, UUID=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
 #
 # swapon /SSS/file00.swap
 # で出来たのですが。。エラーがでて出来ないので。。
 # 原因は btrfs なので。。

#### Leap 15.3 で試してみた 
 
 dd if=/dev/zero of=./file00.img bs=1M count=2048
 dd if=/dev/zero of=./file01.img bs=1M count=4096
 dd if=/dev/zero of=./file02.img bs=1M count=4096
 
 #
 # losetup /SSS/swap00.img /dev/loop99
 # ## と決め打ちでやりたいですが。。
 # swapon /dev/loop99
 
 losetup -f /SSS/file00.img
 losetup -f /SSS/file01.img
 losetup -f /SSS/file02.img
 
 # losetup -l 
 NAME       SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE       DIO LOG-SEC
  /dev/loop1         0      0         0  0 /SSS/file01.img   0     512
  /dev/loop2         0      0         0  0 /SSS/file02.img   0     512
  /dev/loop0         0      0         0  0 /SSS/file00.img   0     512
 
mkswap を使うなと何処かのドキュメントにかかれているのだが。。
 
 # mkswap -f /dev/loop0 
 mkswap: /dev/loop0: warning: wiping old swap signature.
 Setting up swapspace version 1, size = 2 GiB (2147479552 bytes)
 no label, UUID=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 # mkswap -f /dev/loop1 
 mkswap: /dev/loop1: warning: wiping old swap signature.
 Setting up swapspace version 1, size = 4 GiB (4294963200 bytes)
 no label, UUID=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 # mkswap -f /dev/loop2
 mkswap: /dev/loop2: warning: wiping old swap signature.
 Setting up swapspace version 1, size = 4 GiB (4294963200 bytes)
 no label, UUID=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

いままでのやり方。。もしくは xfs でやる場合。。

 # # 4G
 # dd if=/dev/zero of=./file00.swap bs=1M count=2048
 # dd if=/dev/zero of=./file01.swap bs=1M count=4096
 # dd if=/dev/zero of=./file02.swap bs=1M count=4096
 # mkswap -f /SSS/file00.swap
 # mkswap -f /SSS/file01.swap
 # mkswap -f /SSS/file02.swap
 # chmod 0600 /SSS/file00.swap /SSS/file01.swap /SSS/file02.swap
 # ##
 # swapon /SSS/file00.swap
 # swapon /SSS/file01.swap
 # ## swapoff /SSS/file00.swap
 # ## swapoff /SSS/file01.swap
 # 

Swapの頻度の。。
 # swapon -s
 Filename                                Type            Size            Used             Priority
 /dev/nvme0n1p4                          partition       2097148         1674496         -3
 /dev/loop99                             partition       4194300         0               -2
 /dev/loop98                             partition       3158012         0               -4
 # 0 - 100 ( 0:on memory // 100 on swap)
 # cat /proc/sys/vm/swappiness 
 60
 #
 # set +o noclobber
 # echo 70 > /proc/sys/vm/swappiness
 # # echo 10 > /proc/sys/vm/swappiness
 # set -o noclobber
 #
 # swapoff /dev/nvme0n1p4 
 # swapon /dev/nvme0n1p4 
 # swapon -s 
 Filename                                Type            Size            Used            Priority
 /dev/nvme0n1p4                          partition       2097148         0               -4
 /dev/loop99                             partition       4194300         521900          -2
 /dev/loop98                             partition       3158012         0               -3
 #
 # grep VmSwap /proc/*/status | sort -k 2 -r | head

 getconf PAGESIZE