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Faster RNG init

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paboyle
2017-12-05 11:42:05 +00:00
parent d93c6760ec
commit 3e560b9462
1 changed files with 5 additions and 30 deletions
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35
lib/lattice/Lattice_rng.h
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@@ -77,9 +77,6 @@ namespace Grid {
// merge of April 11 2017
//<<<<<<< HEAD
// this function is necessary for the LS vectorised field
inline int RNGfillable_general(GridBase *coarse,GridBase *fine)
{
@@ -91,7 +88,6 @@ namespace Grid {
// all further divisions are local
for(int d=0;d<lowerdims;d++) assert(fine->_processors[d]==1);
for(int d=0;d<rngdims;d++) assert(coarse->_processors[d] == fine->_processors[d+lowerdims]);
// then divide the number of local sites
// check that the total number of sims agree, meanse the iSites are the same
@@ -102,27 +98,6 @@ namespace Grid {
return fine->lSites() / coarse->lSites();
}
/*
// Wrap seed_seq to give common interface with random_device
class fixedSeed {
public:
typedef std::seed_seq::result_type result_type;
std::seed_seq src;
fixedSeed(const std::vector<int> &seeds) : src(seeds.begin(),seeds.end()) {};
result_type operator () (void){
std::vector<result_type> list(1);
src.generate(list.begin(),list.end());
return list[0];
}
};
=======
>>>>>>> develop
*/
// real scalars are one component
template<class scalar,class distribution,class generator>
@@ -171,7 +146,7 @@ namespace Grid {
// support for parallel init
///////////////////////
#ifdef RNG_FAST_DISCARD
static void Skip(RngEngine &eng)
static void Skip(RngEngine &eng,uint64_t site)
{
/////////////////////////////////////////////////////////////////////////////////////
// Skip by 2^40 elements between successive lattice sites
@@ -184,7 +159,8 @@ namespace Grid {
// and margin of safety is orders of magnitude.
// We could hack Sitmo to skip in the higher order words of state if necessary
/////////////////////////////////////////////////////////////////////////////////////
uint64_t skip = 0x1; skip = skip<<40;
uint64_t skip = site;
skip = skip<<40;
eng.discard(skip);
}
#endif
@@ -411,9 +387,7 @@ namespace Grid {
int rank,o_idx,i_idx;
// Everybody loops over global volume.
for(int gidx=0;gidx<_grid->_gsites;gidx++){
Skip(master_engine); // Skip to next RNG sequence
parallel_for(int gidx=0;gidx<_grid->_gsites;gidx++){
// Where is it?
_grid->GlobalIndexToGlobalCoor(gidx,gcoor);
@@ -423,6 +397,7 @@ namespace Grid {
if( rank == _grid->ThisRank() ){
int l_idx=generator_idx(o_idx,i_idx);
_generators[l_idx] = master_engine;
Skip(_generators[l_idx],gidx); // Skip to next RNG sequence
}
}