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Mesh Oriented datABase
(version 5.4.1)
Array-based unstructured mesh datastructure
|
#include "moab/MOABConfig.h"
#include "moab/TupleList.hpp"
#include "moab/ProgOptions.hpp"
#include "moab/ErrorHandler.hpp"
#include <ctime>
#include <iostream>
#include <sstream>
Go to the source code of this file.
Functions | |
int | main (int argc, char **argv) |
Variables | |
const char | BRIEF_DESC [] = "Example of gather scatter with tuple lists \n" |
std::ostringstream | LONG_DESC |
int main | ( | int | argc, |
char ** | argv | ||
) |
Definition at line 62 of file CrystalRouterExample.cpp.
References ProgOptions::addOpt(), BRIEF_DESC, moab::ProcConfig::crystal_router(), moab::TupleList::enableWriteAccess(), ErrorCode, moab::TupleList::get_n(), moab::TupleList::inc_n(), moab::TupleList::initialize(), LONG_DESC, MB_CHK_SET_ERR, moab::MBErrorHandler_Finalize(), moab::MBErrorHandler_Init(), moab::TupleList::print(), moab::ProcConfig::proc_rank(), moab::ProcConfig::proc_size(), size, moab::TupleList::vi_rd, moab::TupleList::vi_wr, moab::TupleList::vl_rd, moab::TupleList::vl_wr, and moab::TupleList::vr_wr.
{
#ifdef MOAB_HAVE_MPI
MPI_Init( &argc, &argv );
// Initialize error handler, required for this example (not using a moab instance)
MBErrorHandler_Init();
ProcConfig pc( MPI_COMM_WORLD );
int size = pc.proc_size();
int rank = pc.proc_rank();
// Start copy
LONG_DESC << "This program does a gather scatter with a list of tuples. \n"
" It tries to see how much communication costs in terms of time and memory. \n"
<< "It starts with creating a list of tuples to be sent from each processor, \n to a "
"list of other processors.\n"
<< "The number of tuples and how many tasks to communicate to are controlled by "
"input parameters.\n"
<< "After communication, we verify locally if we received what we expected. \n";
ProgOptions opts( LONG_DESC.str(), BRIEF_DESC );
// How many procs communicate to current proc, on average (we will vary that too)
int num_comms = 2;
opts.addOpt< int >( "num_comms,n", "each task will send to about num_comms other tasks some tuples (default 2)",
&num_comms );
int num_tuples = 4;
opts.addOpt< int >( "num_tuples,t", "each task will send to some task about num_tuples tuples (default 4)",
&num_tuples );
int reportrank = size + 1;
opts.addOpt< int >( "reporting_rank,r",
"this rank will report the tuples sent and the tuples received; it could "
"be higher than num_procs, then no reporting",
&reportrank );
opts.parseCommandLine( argc, argv );
if( rank == reportrank || ( reportrank >= size && 0 == rank ) )
{
cout << " There are " << size << " tasks in example.\n";
cout << " We will send groups of " << num_tuples << " from each task towards " << num_comms
<< " other tasks.\n";
}
// Send some data from proc i to i + n/2, also to i + n/2 + 1 modulo n, where n is num procs
gs_data::crystal_data* cd = pc.crystal_router();
long total_n_tuples = num_comms * num_tuples;
// Vary the number of tasks to send to, and the number of tuples to send
if( rank < size / 2 )
num_comms--;
else
num_comms++;
if( rank < size / 3 )
num_tuples *= 2;
else if( rank > size - size / 3 )
num_tuples /= 2;
TupleList tl;
// At most num_tuples* num_comms to send
// We do a preallocate with this; some tuples on some processors might need more memory, to be
// able to grow locally; Some tasks might receive more tuples though, and in the process, some
// might grow more than others. By doing these logP sends/receives, we do not grow local memory
// too much.
tl.initialize( 1, 1, 0, 1, num_tuples * num_comms );
tl.enableWriteAccess();
// Form num_tuples*num_comms tuples, send to various ranks
unsigned int n = tl.get_n();
for( int i = 0; i < num_comms; i++ )
{
int sendTo = rank + i * size / 2 + 1; // Spread out the send to, for a stress-like test
sendTo = sendTo % size; //
long intToSend = 1000 * rank + 100000 * sendTo;
for( int j = 0; j < num_tuples; j++ )
{
n = tl.get_n();
tl.vi_wr[n] = sendTo;
tl.vl_wr[n] = intToSend + j;
tl.vr_wr[n] = 10000. * rank + j;
tl.inc_n();
}
}
if( rank == reportrank )
{
cout << "rank " << rank << "\n";
tl.print( " before sending" );
}
clock_t tt = clock();
// All communication happens here; no mpi calls for the user
ErrorCode rval = cd->gs_transfer( 1, tl, 0 );MB_CHK_SET_ERR( rval, "Error in tuple transfer" );
double secs = 0;
if( rank == reportrank || ( reportrank >= size && 0 == rank ) )
{
secs = ( clock() - tt ) / (double)CLOCKS_PER_SEC;
}
if( rank == reportrank )
{
cout << "rank " << rank << "\n";
tl.print( " after transfer" );
}
// Check that all tuples received have the form 10000*rank + 100*from
unsigned int received = tl.get_n();
for( int i = 0; i < (int)received; i++ )
{
int from = tl.vi_rd[i];
long valrec = tl.vl_rd[i];
int remainder = valrec - 100000 * rank - 1000 * from;
if( remainder < 0 || remainder >= num_tuples * 4 )
cout << " error: tuple " << i << " received at proc rank " << rank << " from proc " << from << " has value "
<< valrec << " remainder " << remainder << "\n";
}
if( rank == reportrank || ( reportrank >= size && 0 == rank ) )
{
cout << "communication of about " << total_n_tuples << " tuples/per proc took " << secs << " seconds"
<< "\n";
tt = clock();
}
// Finalize error handler, required for this example (not using a moab instance)
MBErrorHandler_Finalize();
MPI_Finalize();
#else
std::cout << " Build with MPI for this example to work\n";
#endif
return 0;
}
const char BRIEF_DESC[] = "Example of gather scatter with tuple lists \n" |
Definition at line 56 of file CrystalRouterExample.cpp.
std::ostringstream LONG_DESC |
Definition at line 57 of file CrystalRouterExample.cpp.