RPI3 swap experiments ["was killed: out of swap space" with: "v_free_count: 5439, v_inactive_count: 1"]

[bob prohaska]

On Sun, Aug 05, 2018 at 10:39:27AM -0700, Mark Millard wrote:
> 
> "Total Active Working Set too large" (with lots of swap left) seems to be what folks
> are running into in these rpi3/rpi2 examples.
> 
> 
Does the size of the working set vary with how the swap is apportioned between
storage devices? In my observations, 1 GB plus 2 GB swap partitions both on microSD 
allows a -j4 buildworld to run to completion without OOMA intervention. It looks as
if both partitions are burdened equally, so usable swap is actually 2 GB.
 
A pair of 1 GB swap partitions, one on microSD and one on USB flash, invites OOMA 
to intervene prematurely.

Stranger still, 1 GB of swap on microSD, which is insufficient (~1.4 GB required), 
does not trigger OOMA at all, resulting in a hung system.

The RPi3 right now has three swap partitions; one of 1 GB on microSD, one
of 2 GB on microSD and one of 1 GB on USB. Might it shed any light to try 
sysctl vm.swap_idle_enabled=1
just to see if anything changes? My guess is no, but it wouldn't be the first 
time if I'm wrong.

8-)

Thanks for reading!

bob prohaska