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%% demo1_mpe.pl
%%
%% This file was originally created on 3/7/2003
%% by Stasinos Konstantopoulos <konstant@let.rug.nl>
%% as part of the YAP Prolog distribution.
%%
%% This file is in the Public Domain.
%% demo1_mpe.pl is the same as demo1.pl, except
%% that MPE is used to log MPI activity.
% make the `floor' operator return integer values
:- set_prolog_flag(language, iso).
%%
%% This the calculation that needs to be performed, in this case
%% the sum of [From..To]
%%
calc(From, From, Acc, Res) :- !,
Res is Acc + From.
calc(From, To, Acc, Res) :- !,
Acc1 is Acc + To,
To1 is To - 1,
calc(From, To1, Acc1, Res).
%%
%% The master node sends teh task definition to
%% the workers and then collects the results
%%
do(0, NumProc):-
!,
% processing state
mpe_create_event(Ev1),
mpe_create_event(Ev2),
mpe_create_state(Ev1,Ev2,processing,green),
% bcasting state
mpe_create_event(Ev3),
mpe_create_event(Ev4),
mpe_create_state(Ev3,Ev4,bcasting,red),
% sending/recving state
mpe_create_event(Ev5),
mpe_create_event(Ev6),
mpe_create_state(Ev5,Ev6,'sending/receiving',brown),
% pretend that the other nodes do not have
% access to the task definition.
% retrieve it and broadcast it.
get_value(from, From),
get_value(to, To),
mpe_log(Ev3,0,event3),
mpi_bcast(msg(From,To), 0),
mpe_log(Ev4,0,event4),
% loop to collect and accumulate partial results
% from the workers
set_value(n, NumProc),
set_value(acc, 0),
repeat,
mpe_log(Ev5,0,event5),
mpi_receive(T, Source, Tag),
mpe_log(Ev6,0,event6),
format( '0: Proc ~q said: ~q (Tag: ~q)~n', [Source,T,Tag] ),
% accumulate results
get_value(acc, Acc),
NewAcc is Acc + T,
set_value(acc, NewAcc),
% processors still left
get_value(n, Counter),
NewCounter is Counter - 1,
set_value(n, NewCounter),
NewCounter == 1,
!,
format('0: Sum(~q..~q) = ~q.~n', [From,To,NewAcc]).
%%
%% The workers hear from the master what needs to
%% be done, do the work and then send the results back.
%%
do(Rank, NumProc):-
!,
% processing state
mpe_create_event(Ev1),
mpe_create_event(Ev2),
mpe_create_state(Ev1,Ev2,processing,green),
% bcasting state
mpe_create_event(Ev3),
mpe_create_event(Ev4),
mpe_create_state(Ev3,Ev4,bcasting,red),
% sending/recving state
mpe_create_event(Ev5),
mpe_create_event(Ev6),
mpe_create_state(Ev5,Ev6,'sending/receiving',brown),
% catch the task broadcast
mpe_log(Ev3,0,event3),
mpi_bcast(Msg, 0),
mpe_log(Ev4,0,event4),
Msg = msg(From,To),
format( '~q: All are calculating ~q..~q.~n', [Rank,From,To] ),
MyFrom is floor(To * (Rank - 1) / (NumProc - 1)) + From,
MyTo is floor(To * Rank / (NumProc - 1)) + From - 1,
format( '~q: I am calculating ~q..~q.~n', [Rank,MyFrom,MyTo] ),
% do the job
mpe_log(Ev1,0,event1),
calc( MyFrom, MyTo, 0, Result ),
mpe_log(Ev2,0,event2),
format( '~q: sending ~q to 0. (Tag: 1)~n', [Rank,Result] ),
% send back the results
mpe_log(Ev5,0,event5),
mpi_send(Result, 0, 1),
mpe_log(Ev6,0,event6).
%%
%% This is the entry point
%%
start(From, To):-
% store the task definition
set_value(from, From),
set_value(to, To),
mpi_open(Rank, NumProc, ProcName),
format('Rank: ~q NumProc: ~q, ProcName: ~q~n', [Rank,NumProc,ProcName]),
mpe_open,
do(Rank, NumProc),
format( 'Rank ~q finished!~n', [Rank] ),
mpe_close( demo1_mpe ),
mpi_close.
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