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Correct split output #140

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fe28973
corrected output about group splitting, both content and grammar
mpotse Oct 28, 2025
177a88d
moved the printing of split info further down to avoid a deadlock
mpotse Oct 28, 2025
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55 changes: 30 additions & 25 deletions src/grpsplit_pmmg.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1675,17 +1675,17 @@ int PMMG_splitPart_grps( PMMG_pParMesh parmesh,int target,int fitMesh,int redist
if ( parmesh->info.metis_ratio < 0 ) {
/* default value : do not authorize large number of groups */
if ( ngrp > PMMG_REDISTR_NGRPS_MAX ) {
printf(" ## Warning: %s: too much metis nodes needed...\n"
" Partitions may remains freezed. Try to use more processors.\n",
__func__);
printf(" ## Warning: %s: too many metis nodes needed: ngrp=%d\n"
" Partitions may remain frozen. Try to use more processors.\n",
__func__, ngrp);
ngrp = PMMG_REDISTR_NGRPS_MAX;
}
}
if ( ngrp > meshOld->ne ) {
/* Correction if it leads to more groups than elements */
printf(" ## Warning: %s: %d: too much metis nodes needed...\n"
" Partitions may remains freezed. Try to reduce the number of processors.\n",
__func__, parmesh->myrank);
printf(" ## Warning: %s: %d: too many metis nodes needed: ngrp=%d\n"
" Partitions may remain frozen. Try to use fewer processors.\n",
__func__, parmesh->myrank, ngrp);
ngrp = MG_MIN ( meshOld->ne, ngrp );
}
}
Expand All @@ -1699,24 +1699,7 @@ int PMMG_splitPart_grps( PMMG_pParMesh parmesh,int target,int fitMesh,int redist
MPI_CHECK( MPI_Allgather(&parmesh->nold_grp,1,MPI_INT,noldgrps_all,1,MPI_INT,
parmesh->comm), return 0 );

/* Print split info */
int spltinfo[2],spltinfo_all[2*parmesh->nprocs];
if ( parmesh->info.imprim0 > PMMG_VERB_DETQUAL ) {
spltinfo[0] = ngrp;
spltinfo[1] = meshOld->ne;

MPI_CHECK( MPI_Gather(spltinfo,2,MPI_INT,spltinfo_all,2,MPI_INT,0,parmesh->comm),
PMMG_CLEAN_AND_RETURN(parmesh,PMMG_LOWFAILURE) );
}

if ( parmesh->ngrp ) {
if ( parmesh->info.imprim > PMMG_VERB_DETQUAL ) {
int i;
for( i=0; i<parmesh->nprocs; i++ ) {
fprintf(stdout," rank %d splitting %d elts into %d grps\n",
i,spltinfo_all[2*i+1],spltinfo_all[2*i]);
}
}

/* Does the group need to be further subdivided to subgroups or not? */
if ( ngrp == 1 ) {
Expand Down Expand Up @@ -1750,7 +1733,7 @@ int PMMG_splitPart_grps( PMMG_pParMesh parmesh,int target,int fitMesh,int redist
}
}

/* use metis to partition the mesh into the computed number of groups needed
/* Partition the mesh into the computed number of groups needed
part array contains the groupID computed by metis for each tetra */

PMMG_CALLOC(parmesh,part,meshOld->ne,idx_t,"metis buffer ", return 0);
Expand All @@ -1769,7 +1752,7 @@ int PMMG_splitPart_grps( PMMG_pParMesh parmesh,int target,int fitMesh,int redist
if ( ngrp == 1 ) {
if ( parmesh->ddebug )
fprintf( stdout,
"[%d-%d]: %d group is enough, no need to create sub groups.\n",
"[%d-%d]: %d groups is enough, no need to create sub groups.\n",
parmesh->myrank+1, parmesh->nprocs, ngrp );
goto fail_part;
}
Expand All @@ -1788,6 +1771,7 @@ int PMMG_splitPart_grps( PMMG_pParMesh parmesh,int target,int fitMesh,int redist
if( parmesh->info.repartitioning == PMMG_REDISTRIBUTION_ifc_displacement )
if( !PMMG_fix_contiguity_split( parmesh,ngrp,part ) ) return 0;
}

}

/* Split the mesh */
Expand All @@ -1796,6 +1780,27 @@ int PMMG_splitPart_grps( PMMG_pParMesh parmesh,int target,int fitMesh,int redist
fail_part:
PMMG_DEL_MEM(parmesh,part,idx_t,"free metis buffer ");

// Print split info.
// Report after splitting because in case of the interface migration
// method the number of groups is known only afterwards. If we printed it
// before it would report 2 groups on each rank.
int spltinfo[2],spltinfo_all[2*parmesh->nprocs];
if ( parmesh->info.imprim0 > PMMG_VERB_DETQUAL ) {
spltinfo[0] = ngrp;
spltinfo[1] = meshOld->ne;
MPI_CHECK( MPI_Gather(spltinfo,2,MPI_INT,spltinfo_all,2,MPI_INT,0,parmesh->comm),
PMMG_CLEAN_AND_RETURN(parmesh,PMMG_LOWFAILURE) );
}
if ( parmesh->ngrp ) {
if ( parmesh->info.imprim > PMMG_VERB_DETQUAL ) {
int i;
for( i=0; i<parmesh->nprocs; i++ ) {
fprintf(stdout," rank %d split %d elts into %d grps\n",
i,spltinfo_all[2*i+1],spltinfo_all[2*i]);
}
}
}

/* Check the communicators */
assert ( PMMG_check_intNodeComm(parmesh) && "Wrong internal node comm" );
assert ( PMMG_check_intFaceComm(parmesh) && "Wrong internal face comm" );
Expand Down
14 changes: 8 additions & 6 deletions src/loadbalancing_pmmg.c
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Original file line number Diff line number Diff line change
Expand Up @@ -97,7 +97,7 @@ int PMMG_loadBalancing(PMMG_pParMesh parmesh,int partitioning_mode) {
#endif

if ( ier ) {
/** Split the ngrp groups of listgrp into a higher number of groups */
/** Split the ngrp groups of listgrp into a larger number of groups */
ier = PMMG_split_n2mGrps(parmesh,PMMG_GRPSPL_DISTR_TARGET,1,partitioning_mode);
}

Expand All @@ -116,15 +116,17 @@ int PMMG_loadBalancing(PMMG_pParMesh parmesh,int partitioning_mode) {
if ( parmesh->info.imprim > PMMG_VERB_DETQUAL ) {
chrono(OFF,&(ctim[tim]));
printim(ctim[tim].gdif,stim);
fprintf(stdout," group split for metis %s\n",stim);
// this used to say "group split for metis", which is no longer accurate
// as interface migration is not done by Metis anymore
fprintf(stdout," group split for interface migration %s\n",stim);
}

if ( ier_glob <= 0 && parmesh->myrank == parmesh->info.root ) {
fprintf(stderr,"\n ## Problem when splitting into a higher number of groups.\n");
fprintf(stderr,"\n ## Problem when splitting into a larger number of groups.\n");
return ier_glob;
}

/** Distribute the groups over the processor to load balance the meshes */
/** Distribute the groups over the processors to load balance the meshes */
if ( parmesh->info.imprim > PMMG_VERB_DETQUAL ) {
tim = 2;
chrono(ON,&(ctim[tim]));
Expand Down Expand Up @@ -176,7 +178,7 @@ int PMMG_loadBalancing(PMMG_pParMesh parmesh,int partitioning_mode) {
/** Redistribute the ngrp groups of listgrp into a lower number of groups */
ier = PMMG_split_n2mGrps(parmesh,PMMG_GRPSPL_MMG_TARGET,0,partitioning_mode);
if ( ier<=0 )
fprintf(stderr,"\n ## Problem when splitting into a lower number of groups.\n");
fprintf(stderr,"\n ## Problem when splitting into a smaller number of groups.\n");
}

// Algiane: Optim: is this reduce needed?
Expand Down Expand Up @@ -205,7 +207,7 @@ int PMMG_loadBalancing(PMMG_pParMesh parmesh,int partitioning_mode) {
if ( parmesh->info.imprim > PMMG_VERB_DETQUAL ) {
chrono(OFF,&(ctim[tim]));
printim(ctim[tim].gdif,stim);
fprintf(stdout," group split for mmg %s\n",stim);
fprintf(stdout," group split for remeshing %s\n",stim);
}

return ier_glob;
Expand Down
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