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Documentation of MPI examples.

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This commit is contained in:
Benjamin Bouvier 2012-07-16 15:07:48 +02:00
commit b92f17fce5
4 changed files with 219 additions and 21 deletions
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78
eo/test/mpi/t-mpi-parallelApply.cpp
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@ -1,3 +1,41 @@
/*
(c) Thales group, 2012
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation;
version 2 of the License.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Contact: http://eodev.sourceforge.net
Authors:
Benjamin Bouvier <benjamin.bouvier@gmail.com>
*/
/*
* This file shows an example of use of parallel apply, in the following context: each element of a table is
* incremented... in a parallel fashion. While this operation is very easy to perform even on a single host, it's just
* an example for parallel apply use.
*
* Besides, this is also a test for assignment (scheduling) algorithms, in different cases. The test succeeds if and
* only if the program terminates without any segfault ; otherwise, there could be a deadlock which prevents the end or
* a segfault at any time.
*
* One important thing is to instanciate an EmptyJob after having launched a ParallelApplyJob, so as the workers to be
* aware that the job is done (as it's a MultiJob).
*
* This test needs at least 3 processes to be launched. Under this size, it will directly throw an exception, at the
* beginning;
*/
# include <mpi/eoMpi.h>
# include <mpi/eoParallelApply.h>
# include <mpi/eoTerminateJob.h>
@ -9,6 +47,9 @@ using namespace std;
using namespace eo::mpi;
/*
* The function to be called on each element of the table: just increment the value.
*/
struct plusOne : public eoUF< int&, void >
{
void operator() ( int & x )
@ -17,22 +58,26 @@ struct plusOne : public eoUF< int&, void >
}
};
/*
* Internal structure representating a test.
*/
struct Test
{
AssignmentAlgorithm * assign;
string description;
int requiredNodesNumber; // nb : chosen nodes ranks must be sequential
AssignmentAlgorithm * assign; // used assignment algorithm for this test.
string description; // textual description of the test
int requiredNodesNumber; // number of required nodes. NB : chosen nodes ranks must be sequential
};
// These tests require at least 3 processes to be launched.
int main(int argc, char** argv)
{
// eo::log << eo::setlevel( eo::debug );
// eo::log << eo::setlevel( eo::debug ); // if you like tty full of rainbows, decomment this line and comment the following one.
eo::log << eo::setlevel( eo::quiet );
bool launchOnlyOne = false ; // Set this to true if you wanna launch only the first test.
Node::init( argc, argv );
// Initializes a vector with random values.
srand( time(0) );
vector<int> v;
for( int i = 0; i < 1000; ++i )
@ -40,18 +85,27 @@ int main(int argc, char** argv)
v.push_back( rand() );
}
// We need to be sure the values are correctly incremented between each test. So as to check this, we save the
// original vector into a variable originalV, and put an offset variable to 0. After each test, the offset is
// incremented and we can compare the returned value of each element to the value of each element in originalV +
// offset. If the two values are different, there has been a problem.
int offset = 0;
vector<int> originalV = v;
// Instanciates the functor to apply on each element
plusOne plusOneInstance;
vector< Test > tests;
const int ALL = Node::comm().size();
if( ALL < 3 ) {
throw std::runtime_error("Needs at least 3 processes to be launched!");
}
// Tests are auto described thanks to member "description"
Test tIntervalStatic;
tIntervalStatic.assign = new StaticAssignmentAlgorithm( 1, REST_OF_THE_WORLD, v.size() );
tIntervalStatic.description = "Correct static assignment with interval.";
tIntervalStatic.description = "Correct static assignment with interval."; // workers have ranks from 1 to size - 1
tIntervalStatic.requiredNodesNumber = ALL;
tests.push_back( tIntervalStatic );
@ -111,23 +165,32 @@ int main(int argc, char** argv)
for( unsigned int i = 0; i < tests.size(); ++i )
{
// Instanciates a store with the functor, the master rank and size of packet (see ParallelApplyStore doc).
ParallelApplyStore< int > store( plusOneInstance, eo::mpi::DEFAULT_MASTER, 3 );
// Updates the contained data
store.data( v );
// Creates the job with the assignment algorithm, the master rank and the store
ParallelApply< int > job( *(tests[i].assign), eo::mpi::DEFAULT_MASTER, store );
// Only master writes information
if( job.isMaster() )
{
cout << "Test : " << tests[i].description << endl;
}
// Workers whose rank is inferior to required nodes number have to run the test, the other haven't anything to
// do.
if( Node::comm().rank() < tests[i].requiredNodesNumber )
{
job.run();
}
// After the job run, the master checks the result with offset and originalV
if( job.isMaster() )
{
EmptyJob stop( *(tests[i].assign), eo::mpi::DEFAULT_MASTER );
// This job has to be instanciated, not launched, so as to tell the workers they're done with the parallel
// job.
EmptyJob stop( *(tests[i].assign), eo::mpi::DEFAULT_MASTER );
++offset;
for(int i = 0; i < v.size(); ++i)
{
@ -141,6 +204,7 @@ int main(int argc, char** argv)
cout << endl;
}
// MPI synchronization (all the processes wait to be here).
Node::comm().barrier();
delete tests[i].assign;