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mDocumentation of eo::mpi classes.

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Benjamin Bouvier 2012-07-13 14:31:29 +02:00
commit 5e76ba30b0
6 changed files with 409 additions and 14 deletions
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172
eo/src/mpi/eoMpiAssignmentAlgorithm.h
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@ -1,28 +1,118 @@
/*
(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>
*/
# ifndef __MPI_ASSIGNMENT_ALGORITHM_H__
# define __MPI_ASSIGNMENT_ALGORITHM_H__
# include <vector>
# include <vector> // std::vector
# include "eoMpiNode.h"
namespace eo
{
namespace mpi
{
/**
* @brief Constant indicating to use all the resting available workers, in assignment algorithms constructor
* using an interval.
*/
const int REST_OF_THE_WORLD = -1;
/**
* @brief Contains informations on the available workers and allows to find assignees for jobs.
*
* Available workers are workers who aren't processing anything. When they've received an order, workers switch
* from the state "available" to the state "busy", and the master has to wait for their response for considering
* them available again.
*
* @ingroup Parallel
*/
struct AssignmentAlgorithm
{
/**
* @brief Gets the rank of an available worker, so as to send it a task.
*
* @return The MPI rank of an available worker, or -1 if there is no available worker.
*/
virtual int get( ) = 0;
/**
* @brief Gets the number of total available workers.
*
* Before the first call, it is equal to the total number of present workers, as specified in the
* specific assignment algorithm constructor. It allows the Job class to know when all the responses have
* been received, by comparing this number to the total number of workers.
*
* @return Integer indicating how many workers are available.
*/
virtual int availableWorkers( ) = 0;
/**
* @brief Reinject the worker of indicated rank in the available state.
*
* @param wrkRank The MPI rank of the worker who has finished its job.
*/
virtual void confirm( int wrkRank ) = 0;
/**
* @brief Indicates who are the workers which do nothing.
*
* At the end of the algorithm, the master has to warn all the workers that it's done. All the workers mean,
* the workers which are currently processing data, and the other ones who could be waiting : the idles.
* This function indicates to the master which worker aren't doing anything.
*
* @param A std::vector containing all the MPI ranks of the idles workers.
*/
virtual std::vector<int> idles( ) = 0;
/**
* @brief Reinitializes the assignment algorithm with the right number of runs.
*
* In fact, this is only useful for static assignment algorithm, which has to be reinitialized every time
* it's used, in the case of a Multi Job. It's the user's responsability to call this function.
*
* @todo Not really clean. Find a better way to do it.
*/
virtual void reinit( int runs ) = 0;
};
/**
* @brief Assignment (scheduling) algorithm which handles workers in a queue.
*
* With this assignment algorithm, workers are put in a queue and may be called an unlimited number of times.
* Whenever a worker returns, it is added to the queue, and it becomes available for the next call to get().
* The available workers are all located in the queue at any time, so the number of available workers is
* directly equal to the size of the queue.
*
* This kind of assignment is adapted for tasks whose execution time is stochastic or unknown, but without any
* warranty to be faster than other assignments.
*
* @ingroup Parallel
*/
struct DynamicAssignmentAlgorithm : public AssignmentAlgorithm
{
public:
/**
* @brief Uses all the hosts whose rank is higher to 1, inclusive, as workers.
*/
DynamicAssignmentAlgorithm( )
{
for(int i = 1; i < Node::comm().size(); ++i)
@ -31,16 +121,33 @@ namespace eo
}
}
/**
* @brief Uses the unique host with given rank as a worker.
*
* @param unique MPI rank of the unique worker.
*/
DynamicAssignmentAlgorithm( int unique )
{
availableWrk.push_back( unique );
}
/**
* @brief Uses the workers whose ranks are present in the argument as workers.
*
* @param workers std::vector containing MPI ranks of workers.
*/
DynamicAssignmentAlgorithm( const std::vector<int> & workers )
{
availableWrk = workers;
}
/**
* @brief Uses a range of ranks as workers.
*
* @param first The first worker to be included (inclusive)
* @param last The last worker to be included (inclusive). If last == eo::mpi::REST_OF_THE_WORLD, all
* hosts whose rank is higher than first are taken.
*/
DynamicAssignmentAlgorithm( int first, int last )
{
if( last == REST_OF_THE_WORLD )
@ -90,14 +197,43 @@ namespace eo
std::vector< int > availableWrk;
};
/**
* @brief Assignment algorithm which gives to each worker a precise number of tasks to do, in a round robin
* fashion.
*
* This scheduling algorithm attributes, at initialization or when calling reinit(), a fixed amount of runs to
* distribute to the workers. The amount of runs is then equally distributed between all workers ; if total
* number of runs is not a direct multiple of workers number, then remainding unaffected runs are distributed to
* workers from the first to the last, in a round-robin fashion.
*
* This scheduling should be used when the amount of runs can be computed or is fixed and when we guess that the
* duration of processing task will be the same for each run. There is no warranty that this algorithm is more
* or less efficient that another one. When having a doubt, use DynamicAssignmentAlgorithm.
*
* @ingroup Parallel
*/
struct StaticAssignmentAlgorithm : public AssignmentAlgorithm
{
public:
/**
* @brief Uses a given precise set of workers.
*
* @param workers std::vector of MPI ranks of workers which will be used.
* @param runs Fixed amount of runs, strictly positive.
*/
StaticAssignmentAlgorithm( std::vector<int>& workers, int runs )
{
init( workers, runs );
}
/**
* @brief Uses a range of workers.
*
* @param first The first MPI rank of worker to use
* @param last The last MPI rank of worker to use. If it's equal to REST_OF_THE_WORLD, then all the
* workers from the first one are taken as workers.
* @param runs Fixed amount of runs, strictly positive.
*/
StaticAssignmentAlgorithm( int first, int last, int runs )
{
std::vector<int> workers;
@ -114,6 +250,12 @@ namespace eo
init( workers, runs );
}
/**
* @brief Uses all the hosts whose rank is higher than 1 (inclusive) as workers.
*
* @param runs Fixed amount of runs, strictly positive. If it's not set, you'll have to call reinit()
* later.
*/
StaticAssignmentAlgorithm( int runs = 0 )
{
std::vector<int> workers;
@ -125,6 +267,12 @@ namespace eo
init( workers, runs );
}
/**
* @brief Uses an unique host as worker.
*
* @param unique The MPI rank of the host which will be the worker.
* @param runs Fixed amount of runs, strictly positive.
*/
StaticAssignmentAlgorithm( int unique, int runs )
{
std::vector<int> workers;
@ -133,15 +281,31 @@ namespace eo
}
private:
/**
* @brief Initializes the static scheduling.
*
* Gives to each worker an equal attribution number, equal to runs / workers.size(), eventually plus one
* if number of workers is not a divisor of runs.
*
* @param workers Vector of hosts' ranks
* @param runs Fixed amount of runs, strictly positive.
*/
void init( std::vector<int> & workers, int runs )
{
unsigned int nbWorkers = workers.size();
freeWorkers = nbWorkers;
attributions.clear();
attributions.reserve( nbWorkers );
busy.clear();
busy.resize( nbWorkers, false );
realRank = workers;
if( runs <= 0 )
{
return;
}
attributions.clear();
attributions.reserve( nbWorkers );
// Let be the euclidean division of runs by nbWorkers :
// runs == q * nbWorkers + r, 0 <= r < nbWorkers
@ -151,8 +315,6 @@ namespace eo
// r requests to workers, in ascending order
unsigned int diff = runs - (runs / nbWorkers) * nbWorkers;
for (unsigned int i = 0; i < diff; ++attributions[i++]);
realRank = workers;
}
public: