RPI3 swap experiments

[bob prohaska]

On Wed, Jun 27, 2018 at 06:12:53PM -0700, Mark Millard wrote:
> 
> It would be handy for something simpler than buildworld to be
> able to induce some of the types of problems, for sure.
> 

It appears that running
root at www:/home/bob/stress2/misc # sh ./snap.sh > 5thstress2.log & 
triggers a stream of console errors that resemble those produced
by -j4 buildworld:

GEOM: md10: invalid disklabel.
GEOM: ufsid/5a5a128b05c5944d: invalid disklabel.
(da0:umass-sim0:0:0:0): WRITE(10). CDB: 2a 00 00 18 a9 80 00 00 30 00 
(da0:umass-sim0:0:0:0): CAM status: CCB request completed with an error
(da0:umass-sim0:0:0:0): Retrying command, 3 more tries remain
(da0:umass-sim0:0:0:0): WRITE(10). CDB: 2a 00 00 18 a9 80 00 00 30 00 

The error stream continues until powercycling, escape to debugger does
not work. To some extent, the machine remains responsive in ssh sessions,
at least for simple commands (ls -l, tail). The stress2 logfile is empty.

The details captured are visible at

http://www.zefox.net/~fbsd/rpi3/swaptests/r335655/1gbsdflash/stress2/5thtest/

One oddity is a stream of indisplayable characters, briefly, in
http://www.zefox.net/~fbsd/rpi3/swaptests/r335655/1gbsdflash/stress2/5thtest/5thswapuse.log
following the initial error message.

Another oddity is that during a single user reboot similar errors are briefly
displayed before starting the shell. After two rounds of fsck -f they seem to
vanish, not to return without appropriate provocation. This does not happen on
every reboot, but enough to be no-longer surprising.

It looks as if this particular error message has nothing at all to do with swap.
Does it seem in any way related to similar errors seen during swap-stressed
buildworld sessions?

Thanks for reading,

bob prohaska