lammps/lib/gpu/pair_gpu_nbor.cu

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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
Copyright (2003) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Contributing authors: Mike Brown (SNL), wmbrown@sandia.gov
Peng Wang (Nvidia), penwang@nvidia.com
Paul Crozier (SNL), pscrozi@sandia.gov
------------------------------------------------------------------------- */
#include "pair_gpu_nbor.h"
int PairGPUNbor::bytes_per_atom(const int max_nbors) const {
if (_use_packing)
return (max_nbors*2+4)*sizeof(int);
else
return (max_nbors+3)*sizeof(int);
}
bool PairGPUNbor::init(const int ij_size, const int max_atoms,
const int max_nbors) {
bool success=true;
if (allocated)
clear();
// Initialize timers for the selected GPU
time_nbor.init();
if (_use_packing)
success=success && dev_nbor.alloc((max_nbors+4)*max_atoms);
else
success=success && dev_nbor.alloc(3*max_atoms);
success=success && ij.alloc(max_nbors*max_atoms);
success=success && host_ij.alloc_w(ij_size);
allocated=true;
return success;
}
void PairGPUNbor::resize(const int nlocal, const int max_nbor, bool &success) {
dev_nbor.clear();
ij.clear();
if (_use_packing)
success=success && dev_nbor.alloc((max_nbor+4)*nlocal);
else
success=success && dev_nbor.alloc(3*nlocal);
success=success && ij.alloc(max_nbor*nlocal);
allocated=true;
}
void PairGPUNbor::clear() {
if (!allocated)
return;
allocated=false;
ij.clear();
host_ij.clear();
dev_nbor.clear();
}
double PairGPUNbor::host_memory_usage() const {
return IJ_SIZE*sizeof(int)+sizeof(PairGPUNbor);
}
void PairGPUNbor::reset(const int inum, int *ilist, const int *numj,
cudaStream_t &s) {
ij_total=0;
dev_nbor.copy_from_host(ilist,inum);
int acc=0;
int ij_size=host_ij.numel();
if (inum*2<ij_size) {
for (int i=0; i<inum; i++) {
host_ij[i]=numj[ilist[i]];
host_ij[i+inum]=acc;
acc+=numj[ilist[i]];
}
host_ij.copy_to_device(dev_nbor.begin()+inum,2*inum, s);
} else {
int offset=0;
int half=ij_size/2;
int hi=0;
for (int i=0; i<inum; i++) {
host_ij[hi]=numj[ilist[i]];
host_ij[hi+half]=acc;
acc+=numj[ilist[i]];
hi++;
if (hi==half) {
host_ij.copy_to_device(dev_nbor.begin()+inum+offset,half,s);
host_ij.copy_to_device(half,dev_nbor.begin()+2*inum+offset,half,s);
offset+=half;
hi=0;
CUDA_SAFE_CALL(cudaStreamSynchronize(s));
}
}
if (hi>0) {
host_ij.copy_to_device(dev_nbor.begin()+inum+offset,hi,s);
host_ij.copy_to_device(half,dev_nbor.begin()+2*inum+offset,hi,s);
}
}
}