Skip to main content

Linux Swap 管理 (Swap Management)

apk add util-linux-misc # util-linux 提供全功能的 swap 工具

swapon --show   # 查看交换区
cat /proc/swaps #
  • Swap Files:
    • Ubuntu: /swap.img
    • macOS: /private/var/vm/swapfile*
    • Windows: C:\pagefile.sys
    • Generic: /swapfile

Linux uses swappiness to control swap usage.

  • vm.swappiness (0-100), default 60.
  • 0: Avoid swap as much as possible.
  • 10: Use swap when 90% memory is filled (10% free).
  • 100: Aggressive swapping.

[!NOTE] vm.swappiness modification requires reboot or sysctl -p to persist, but takes effect immediately if written to /proc.

# Linux
# 永久修改 /etc/sysctl.conf -> sysctl -p
# 运行时修改:
sysctl vm.swappiness=10

# Operations
swapoff -a        # Disable all swap
swapon -a         # Enable all swap
cat /proc/meminfo # Check memory/swap
free -h           # Show usage
top               # Monitor
cat /proc/swaps   # List swap devices
vmstat            # Virtual memory stats

# macOS
vm_stat                          # Virtual memory stats
ls -lh /private/var/vm/swapfile* # List swap files

# Alpine Linux
echo vm.swappiness=10 > /etc/sysctl.d/swap.conf
/etc/init.d/sysctl restart
rc-update add swap boot

添加 swap​

# 4G 交换区
# dd if=/dev/zero of=/sysswap count=512 bs=8MiB status=progress
fallocate -l 4G /sysswap

chmod 600 /sysswap
mkswap /sysswap
swapon /sysswap
# 将 swap 添加到 fstab
echo /sysswap swap swap sw 0 0 >> /etc/fstab

sysctl vm.swappiness=10

删除 swap​

# 先关闭 swap
swapoff /sysswap
# 删除 swap 文件
rm -f /sysswap
# 删除 fstab 中的 swap
sed -i '/\/sysswap/d' /etc/fstab

参考​