spurious out of swap kills

[Trev]

[From the FreeBSD-Current mailing list]

Konstantin Belousov wrote on 13/09/2019 15:53:
> Basically, page fault handler waits for vm.pfault_oom_wait *
> vm.pfault_oom_attempts for a page allocation before killing the process.
> Default is 30 secs, and if you cannot get a page for 30 secs, there is
> something very wrong with the machine.

This may well explain the oom kills that were being experienced on 
several Raspberry Pi 3B+ boards using the microSD as swap and why 
upgrading the microSD to the fastest available or using a USB attached 
hard drive did not suffer from the issue.