demo1_mpe.pl

%% 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.
 
:- use_module(library(mpi)).
:- use_module(library(mpe)).
 
 
%% 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) :- calc,
    Res is Acc + From.
calc(From, To, Acc, Res) :- calc,
    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):-
    do,
 
    % 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),
    set_value,
      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,
    set_value,
    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):-
    do,
 
    % 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]),
    format,
    do(Rank, NumProc),
    format( 'Rank ~q finished!~n', [Rank] ),
    mpe_close( demo1_mpe ),
    mpe_close.