Counters do not require a handler at the target, but will add significant
overhead for **short** put/get transfers on shared memory systems. If the
system does not have an atomic fetch&add operation, then the caller will need
to execute lock_counter; read_counter; increment_counter; write_counter;
unlock_counter. This is the reason I presented this counter feature in a
separate section, asking for a separate vote: it makes sense in the context of
distributed memory implementations, but makes less sense for shared memory
systems, and adds some complexity to the user. Remember, however, that no
overhead is incurred when the increment is zero, i.e., when the feature is not
used (except the overhead of reading an extra argument and testing for zero).
Marc Snir
IBM T.J. Watson Research Center
P.O. Box 218, Yorktown Heights, NY 10598
email: snir@watson.ibm.com
phone: 914-945-3204
fax: 914-945-4425
URL: http://www.research.ibm.com/people/s/snir