linux 增加虚拟内存

mkdir /swaps
dd if=/dev/zero of=/swapfile bs=1024 count=20480000      ##20G

mkswap /swaps/1.swap
swapon /swaps/1.swap
# check state
swapon -s

# turn off
swapoff
# set auto boot

# 随机启动：添加一行到/etc/fstab
/swaps/1.swap none swap sw 0 0