https://unix.stackexchange.com/a/630080/2972

If the system has 10GB RAM, then --memsuspend 20% should do exactly the same as --memsuspend 2G so GNU Parallel simply does the calculation for you.

It will require updating memfreescript to also return the total memory available. This seems easy on:

linux: /proc/meminfo MemTotal

android: /proc/meminfo MemTotal

cygwin: /proc/meminfo MemTotal

FreeBSD:
$ sysctl hw.physmem
$ sysctl hw | egrep 'hw.(phys|user|real)'

darwin: sysctl -a | grep hw.memsize

Unknown on: solaris, hpux

Also fix this:

             ((defined $opt::memsuspend) ? "--memfree ".$opt::memsuspend : ""),