RPI3 swap experiments

[Mark Millard]

On 2018-Jul-18, at 8:53 PM, John Kennedy <warlock at phouka.net> wrote:

> On Tue, Jul 17, 2018 at 11:06:50PM -0700, bob prohaska wrote:
>> It appears that some progress has been made in getting swap working reasonably
>> on the RPI3. A -j4 buildworld attempt running r336356 to compile 336431 failed
>> with "out of swap" but the worst read and write delays were less than 5 seconds,
>> a marked improvement over previous examples.
>> 
>> In this case swap was split, 2 each 1GB  partitions on USB flash plus 1 GB on the 
>> microSD card. Previous attempts using 3 each 1 GB partitions on USB flash have been
>> repeatedly successful, while a single attempt using 3 each 1GB partitions on microSD
>> failed.
> 
>  So I've got a RPI3B+.  YMMV.
> 
>  I've recompiled 12 ~7 times since June 27th and run into a handful of
> problems but haven't had issues lately.  I think I started out with the
> stock images (*-RPI3-20180618-r335317 and *-RPI3-20180709-r336134).
> 
>  I had OOM problems, so added swap (typical swap-on-ufs).  Could only get
> ~3.6G of swap without triggering the kern.maxswzone warning, and then had the
> pauses (forget the exact text, but basically FreeBSD telling me that something
> disk related had timed out after ~20 secs).  That stopped being a problem as
> I took the stock images and created a real freebsd-swap partition (and maybe
> a SDCARD upgrade).

See bugzilla 206048 ( https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=206048 )
for what tends to happen with swap files (including swap in ufs files). The
technical/FreeBSD-internal material is in or referenced-in Comments 7 & 8.

This issue is separate from what Bob P. has been dealing with for swap
partitions.

> . . .

===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)