# dd if=/dev/zero of=/root/myswapfile bs=1M count=1024

1024+0 records in

1024+0 records out

# ls -l /root/myswapfile

-rw-r--r--    1 root     root     1073741824 Aug 14 23:47 /root/myswapfile

# chmod 600 /root/myswapfile

# mkswap /root/myswapfile

Setting up swapspace version 1, size = 1073737 kB

# swapon /root/myswapfile

# cat /etc/fstab  # 添加下面这句

/root/myswapfile               swap                    swap    defaults        0 0

# swapon -s

Filename                        Type            Size    Used    Priority

/dev/sda2                       partition       4192956 0       -1

/root/myswapfile                file            1048568 0       -2

# free -k

             total       used       free     shared    buffers     cached

Mem:       3082356    3022364      59992          0      52056    2646472

-/+ buffers/cache:     323836    2758520

Swap:      5241524          0    5241524

# swapoff -a

# swapon -a