RPI3 swap experiments

[bob prohaska]

On Tue, Jul 31, 2018 at 01:49:57PM -0700, Mark Millard wrote:
> On 2018-Jul-31, at 12:10 PM, bob prohaska <fbsd at www.zefox.net> wrote:
> 
> 
> > Some weeks (months?) ago there was a thread about swap being broken. Was
> > that in any way related to what I'm seeing?
> 
> There was some ZFS context stuff that seemed to be independent of
> UFS stuff relative to memory use. I continue to see reports tied
> to ZFS contexts.
> 
> But I'm not sure if this is in any way related to what you are
> calling "swap being broken". I do not remember anything about
> swap being directly broken for swap partitions. (Swap files are
> a different issue and are problematical.)
> 

The thread I'm referring to starts with 
https://lists.freebsd.org/pipermail/freebsd-current/2018-June/069728.html and titled
" swapping is completely broken in -CURRENT r334649? "

There's no mention whether ARM is affected, just "certain hardware". 
It looks like a bug was introduced in r329882 and fixed in r334752.
Workarounds suggested  include 
sysctl vm.pageout_update_period=0
and
sysctl vm.pageout_update_period=1000. 

Maybe the first will turn OOMA off, and the second delay it? 
On  RPi the value is 600. The one correspondent who tried 1000
said it didn't help, maybe zero is a better guess. For me it's
a shot in total darkness either way 8-) 

Thanks for reading!

bob prohaska