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Stencil now runs with coalesced accesses

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This commit is contained in:
Peter Boyle 2019-05-18 17:40:35 +01:00
parent a584b16c4a
commit 6c4da3bbc7
1 changed files with 95 additions and 10 deletions
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105
Grid/stencil/Stencil.h
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@ -55,6 +55,45 @@ NAMESPACE_BEGIN(Grid);
///////////////////////////////////////////////////////////////////
// Gather for when there *is* need to SIMD split with compression
///////////////////////////////////////////////////////////////////
#ifdef __CUDA_ARCH__
//////////////////////////////////////////
// EExtract and insert slices on the GPU
//////////////////////////////////////////
template<class vobj> accelerator_inline
typename vobj::scalar_object coalescedRead(const vobj & __restrict__ vec)
{
typedef typename vobj::scalar_type scalar_type;
typedef typename vobj::vector_type vector_type;
constexpr int Nsimd = sizeof(vector_type)/sizeof(scalar_type);
int lane = threadIdx.x % Nsimd;
return extractLane(lane,vec);
}
template<class vobj> accelerator_inline
void coalescedWrite(vobj & __restrict__ vec,const typename vobj::scalar_object & __restrict__ extracted)
{
typedef typename vobj::scalar_type scalar_type;
typedef typename vobj::vector_type vector_type;
constexpr int Nsimd = sizeof(vector_type)/sizeof(scalar_type);
int lane = threadIdx.x % Nsimd;
insertLane(lane,vec,extracted);
}
#else
//////////////////////////////////////////
// Trivial mapping of vectors on host
//////////////////////////////////////////
template<class vobj> accelerator_inline
vobj coalescedRead(const vobj & __restrict__ vec)
{
return vec;
}
template<class vobj> accelerator_inline
void coalescedWrite(vobj & __restrict__ vec,const vobj & __restrict__ extracted)
{
vec = extracted;
}
#endif
void Gather_plane_table_compute (GridBase *grid,int dimension,int plane,int cbmask,
int off,Vector<std::pair<int,int> > & table);
@ -66,11 +105,30 @@ void Gather_plane_simple_table (Vector<std::pair<int,int> >& table,const Lattice
{
int num=table.size();
std::pair<int,int> *table_v = & table[0];
auto rhs_v = rhs.View();
// auto tmp_ucc = coalescedRead(rhs_v[so+table_v[0].second]);
// coalescedWrite(rhs_v[so+table_v[0].second],tmp_ucc);
#if 1
typedef typename vobj::scalar_type scalar_type;
typedef typename vobj::vector_type vector_type;
constexpr int Nsimd = sizeof(vector_type)/sizeof(scalar_type);
accelerator_loopNB( ii,num*Nsimd, {
typedef decltype(coalescedRead(buffer[0])) compressed_t;
typedef decltype(coalescedRead(rhs_v [0])) uncompressed_t;
int i = ii/Nsimd;
compressed_t tmp_c;
uncompressed_t tmp_uc = coalescedRead(rhs_v[so+table_v[i].second]);
uint64_t o = table_v[i].first;
compress.Compress(&tmp_c,0,tmp_uc);
coalescedWrite(buffer[off+o],tmp_c);
});
#else
accelerator_loopN( i,num, {
compress.Compress(&buffer[off],table_v[i].first,rhs_v[so+table_v[i].second]);
});
#endif
// Further optimisatoin: i) streaming store the result
// ii) software prefetch the first element of the next table entry
}
@ -224,7 +282,7 @@ public:
}
int face_table_computed;
Vector<Vector<std::pair<int,int> > > face_table ;
std::vector<Vector<std::pair<int,int> > > face_table ;
Vector<int> surface_list;
Vector<StencilEntry> _entries; // Resident in managed memory
@ -259,10 +317,12 @@ public:
double mergetime;
double decompresstime;
double comms_bytes;
double shm_bytes;
double splicetime;
double nosplicetime;
double calls;
std::vector<double> comm_bytes_thr;
std::vector<double> shm_bytes_thr;
std::vector<double> comm_time_thr;
std::vector<double> comm_enter_thr;
std::vector<double> comm_leave_thr;
@ -326,6 +386,8 @@ public:
Packets[i].from_rank,
Packets[i].bytes,i);
comm_bytes_thr[mythread] += bytes;
shm_bytes_thr[mythread] += 2*Packets[i].bytes-bytes; // Send + Recv.
}
comm_leave_thr[mythread]= usecond();
comm_time_thr[mythread] += comm_leave_thr[mythread] - comm_enter_thr[mythread];
@ -343,11 +405,13 @@ public:
double t0 = comm_enter_thr[t];
double t1 = comm_leave_thr[t];
comms_bytes+=comm_bytes_thr[t];
shm_bytes +=shm_bytes_thr[t];
comm_enter_thr[t] = 0.0;
comm_leave_thr[t] = 0.0;
comm_time_thr[t] = 0.0;
comm_bytes_thr[t]=0;
shm_bytes_thr[t]=0;
if ( first == 0.0 ) first = t0; // first is t0
if ( (t0 > 0.0) && ( t0 < first ) ) first = t0; // min time seen
@ -362,12 +426,14 @@ public:
reqs.resize(Packets.size());
commtime-=usecond();
for(int i=0;i<Packets.size();i++){
comms_bytes+=_grid->StencilSendToRecvFromBegin(reqs[i],
uint64_t bytes=_grid->StencilSendToRecvFromBegin(reqs[i],
Packets[i].send_buf,
Packets[i].to_rank,
Packets[i].recv_buf,
Packets[i].from_rank,
Packets[i].bytes,i);
comms_bytes+=bytes;
shm_bytes +=2*Packets[i].bytes-bytes;
}
}
@ -391,12 +457,14 @@ public:
if (mythread < nthreads) {
for (int i = mythread; i < Packets.size(); i += nthreads) {
double start = usecond();
comm_bytes_thr[mythread] += _grid->StencilSendToRecvFrom(Packets[i].send_buf,
Packets[i].to_rank,
Packets[i].recv_buf,
Packets[i].from_rank,
Packets[i].bytes,i);
comm_time_thr[mythread] += usecond() - start;
uint64_t bytes= _grid->StencilSendToRecvFrom(Packets[i].send_buf,
Packets[i].to_rank,
Packets[i].recv_buf,
Packets[i].from_rank,
Packets[i].bytes,i);
comm_bytes_thr[mythread] += bytes;
shm_bytes_thr[mythread] += Packets[i].bytes - bytes;
comm_time_thr[mythread] += usecond() - start;
}
}
}
@ -610,7 +678,8 @@ public:
const std::vector<int> &directions,
const std::vector<int> &distances,
Parameters p)
: comm_bytes_thr(npoints),
: shm_bytes_thr(npoints),
comm_bytes_thr(npoints),
comm_enter_thr(npoints),
comm_leave_thr(npoints),
comm_time_thr(npoints)
@ -1189,6 +1258,7 @@ public:
comm_bytes_thr[i]=0;
comm_enter_thr[i]=0;
comm_leave_thr[i]=0;
shm_bytes_thr[i]=0;
}
halogtime = 0.;
mergetime = 0.;
@ -1197,6 +1267,7 @@ public:
splicetime = 0.;
nosplicetime = 0.;
comms_bytes = 0.;
shm_bytes = 0.;
calls = 0.;
};
@ -1213,6 +1284,7 @@ public:
if ( comm_time_thr[i]>0.0 ) {
threaded = 1;
comms_bytes += comm_bytes_thr[i];
shm_bytes += shm_bytes_thr[i];
if (t < comm_time_thr[i]) t = comm_time_thr[i];
}
}
@ -1232,6 +1304,19 @@ public:
std::cout << GridLogMessage << " Stencil " << comms_bytes/commtime/1000. << " GB/s per rank"<<std::endl;
std::cout << GridLogMessage << " Stencil " << comms_bytes/commtime/1000.*NP/NN << " GB/s per node"<<std::endl;
}
if(shm_bytes>1.0){
PRINTIT(shm_bytes); // X bytes + R bytes
// Double this to include spin projection overhead with 2:1 ratio in wilson
auto gatheralltime = gathertime+gathermtime;
auto allbytes = comms_bytes+shm_bytes;
std::cout << GridLogMessage << " Stencil SHM " << (shm_bytes)/gatheralltime/1000. << " GB/s per rank"<<std::endl;
std::cout << GridLogMessage << " Stencil SHM " << (shm_bytes)/gatheralltime/1000.*NP/NN << " GB/s per node"<<std::endl;
auto membytes = (shm_bytes + comms_bytes/2) // read/write
+ (shm_bytes+comms_bytes)/2 * sizeof(vobj)/sizeof(cobj);
std::cout << GridLogMessage << " Stencil SHM mem " << (membytes)/gatheralltime/1000. << " GB/s per rank"<<std::endl;
std::cout << GridLogMessage << " Stencil SHM mem " << (membytes)/gatheralltime/1000.*NP/NN << " GB/s per node"<<std::endl;
}
PRINTIT(mpi3synctime);
PRINTIT(mpi3synctime_g);
PRINTIT(shmmergetime);