The default memory (RAM) limit for r.watershed is pretty low by default.
With this option, the RAM usage can be set in order to use the full
power of the current machine.
Sorry so late, I resolved this now in a separate commit (be81200a5d7754f84d3058f73fa972981a522552), couldn't add to the PR. If the rwatershedmemoryoption is given, the -m is set automatically.
The default memory (RAM) limit for r.watershed is pretty low by default. With this option, the RAM usage can be set in order to use the full power of the current machine.