21
Message Passing Example
In message passing,
there is no abstraction … the programmer does everything
•Consider
overlapping comm/comp
•When
exchanging data in middle of a computation
nb_send(to_right,
data1);
much computing;
recv(from_left, loc1);
•The programmer knows that data1
will not be used, and so there can be no error in delaying the recv
•… but
compilers usually must be
much
more conservative
l
Compiler uses blocking send