'A "Performance Counter" is a stable, known, common counter,
such as Memory, or Processor.  The use of addperfcounter by
end-users is deprecated, since the use of
addcounterbybrowsing is considerably more flexible and general.
It is provided here to allow the easy development of scripts
which need to access variables so common we know them by name
(such as Memory|Available Bytes), and to provide symmetry with
the add inst counter method.
usage:
query.addperfcounter(\'Memory\', \'Available Bytes\')
It is just as easy to access addcounter directly, the following
has an identicle effect.
query.addcounter(\'Memory\', \'Available Bytes\')'

def addperfcounter(self, object, counter, machine=None):

    BaseQuery.addcounter(self, object=object, counter=counter, machine=machine)
