RPI3 swap experiments

[Trev]

Ok, the final, final swap experiment.

I created a 2G swap partition on the SDCard:

gpart show
=>      63  31116225  mmcsd0  MBR  (15G)
         63      2016          - free -  (1.0M)
       2079    102400       1  fat32lba  [active]  (50M)
     104479  31011809       2  freebsd  (15G)

=>       0  31011809  mmcsd0s2  BSD  (15G)
          0  25165824         1  freebsd-ufs  (12G)
   25165824   4194304         2  freebsd-swap  (2.0G)
   29360128   1651681            - free -  (806M)

and, yes, it still died during make -j4 buildworld:

Jul  3 22:15:24 rpi3 kernel: pid 57011 (c++), uid 0, was killed: out of 
swap space

(I forgot to start the logging script, so no stats).

Conclusion: The only way to buildworld on the RPi3B+ is to use an 
external USB mechanical hard disk (my hybrid Seagate 500G 2.5" drive 
required a powered USB hub). No issues on a RPi2B v1.1 with swap and 
/usr on a USB memory key.