I don't know why nodemanger uses extra mem,about 600mb. I tried to limit heap space of nodemanager.
as far as i know heap space setting for nodemanager was located at $Domain/bin/startNodemanager
but it seems it has been changed. where is heap space setting for NM located?
See here: NodeManager Heap Size Change In WebLogic 12.2.1 and 184.108.40.206 and Higher (Doc ID 2189734.1)
But it neds some mmory to work ;-)