手动添加Swap分区，内存不够的时候可以尝试用用
pi@raspberrypi:~/zengjf $ mkdir swap
pi@raspberrypi:~/zengjf $ cd swap/
pi@raspberrypi:~/zengjf/swap $ dd if=/dev/zero of=swapfree bs=32k count=1024
1024+0 records in
1024+0 records out
33554432 bytes (34 MB, 32 MiB) copied, 0.202008 s, 166 MB/s
pi@raspberrypi:~/zengjf/swap $ ls
swapfree
pi@raspberrypi:~/zengjf/swap $ /sbin/mkswap swapfree
mkswap: swapfree: insecure permissions 0644, 0600 suggested.
Setting up swapspace version 1, size = 32 MiB (33550336 bytes)
no label, UUID=b93502fa-ca0e-42e4-bdc2-e0fbf5b6e3a8
pi@raspberrypi:~/zengjf/swap $ sudo /sbin/swapon swapfree
swapon: /home/pi/zengjf/swap/swapfree: insecure permissions 0644, 0600 suggested.
swapon: /home/pi/zengjf/swap/swapfree: insecure file owner 1000, 0 (root) suggested.
pi@raspberrypi:~/zengjf/swap $ free
free freeze_graph
pi@raspberrypi:~/zengjf/swap $ free -m
total used free shared buff/cache available
Mem: 3854 195 3219 11 440 3526
Swap: 131 0 131
pi@raspberrypi:~/zengjf/swap $ /sbin/swapon -s
Filename Type Size Used Priority
/var/swap file 102396 0 -2
/home/pi/zengjf/swap/swapfree file 32764 0 -3
pi@raspberrypi:~/zengjf/swap $ cat /proc/sys/vm/swappiness
60