The vm.v_free_target sysctl represents the target number of free pages for the
vm system. It is calculated by adding together the setpoints for each memory
domain.
When written to it does not propagate the new targets back to the domain.
Modify the sysctl to be a proc and equally distribute the target across each of
the domains.
Without this fix we have a customer report of the sysctl not working, this
fixes their expected behaviour.
We are not sure if this is the correct approach, better might be to make this
sysctl read only and update the target when any pid controllers set point is
updated. This modification has the benefit of only exposing a single value for
an operator to fiddle with.