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pair_gpu_nbor.cpp
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Fri, Nov 8, 06:12

pair_gpu_nbor.cpp
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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 (ORNL), brownw@ornl.gov
Peng Wang (Nvidia), penwang@nvidia.com
------------------------------------------------------------------------- */
#include "pair_gpu_precision.h"
#include "pair_gpu_nbor.h"
#include "pair_gpu_device.h"
#include "math.h"
int PairGPUNbor::bytes_per_atom(const int max_nbors) const {
if (_gpu_nbor)
return (max_nbors+2)*sizeof(int);
else if (_use_packing)
return ((max_nbors+2)*2)*sizeof(int);
else
return (max_nbors+3)*sizeof(int);
}
bool PairGPUNbor::init(PairGPUNborShared *shared, const int inum,
const int host_inum, const int max_nbors,
const int maxspecial, UCL_Device &devi,
const bool gpu_nbor, const int gpu_host,
const bool pre_cut, const int block_cell_2d,
const int block_cell_id, const int block_nbor_build) {
clear();
_block_cell_2d=block_cell_2d;
_block_cell_id=block_cell_id;
_block_nbor_build=block_nbor_build;
_shared=shared;
dev=&devi;
_gpu_nbor=gpu_nbor;
if (gpu_host==0)
_gpu_host=false;
else if (gpu_host==1)
_gpu_host=true;
else
// Not yet implemented
assert(0==1);
if (pre_cut || gpu_nbor==false)
_alloc_packed=true;
else
_alloc_packed=false;
bool success=true;
// Initialize timers for the selected GPU
time_nbor.init(*dev);
time_kernel.init(*dev);
time_nbor.zero();
time_kernel.zero();
_max_atoms=static_cast<int>(static_cast<double>(inum)*1.10);
if (_max_atoms==0)
_max_atoms=1000;
_max_host=static_cast<int>(static_cast<double>(host_inum)*1.10);
_max_nbors=max_nbors;
_maxspecial=maxspecial;
if (gpu_nbor==false)
_maxspecial=0;
if (gpu_nbor==false)
success=success && (host_packed.alloc(2*IJ_SIZE,*dev,
UCL_WRITE_OPTIMIZED)==UCL_SUCCESS);
alloc(success);
if (!success)
return false;
if (_use_packing==false)
_shared->compile_kernels(devi,gpu_nbor);
return success;
}
void PairGPUNbor::alloc(bool &success) {
dev_nbor.clear();
host_acc.clear();
int nt=_max_atoms+_max_host;
if (_use_packing==false || _gpu_nbor)
success=success && (dev_nbor.alloc((_max_nbors+2)*_max_atoms,*dev,
UCL_READ_ONLY)==UCL_SUCCESS);
else
success=success && (dev_nbor.alloc(3*_max_atoms,*dev,
UCL_READ_ONLY)==UCL_SUCCESS);
success=success && (host_acc.alloc(nt*2,*dev,
UCL_WRITE_OPTIMIZED)==UCL_SUCCESS);
_c_bytes=dev_nbor.row_bytes();
if (_alloc_packed) {
dev_packed.clear();
success=success && (dev_packed.alloc((_max_nbors+2)*_max_atoms,*dev,
UCL_READ_ONLY)==UCL_SUCCESS);
_c_bytes+=dev_packed.row_bytes();
}
if (_max_host>0) {
host_nbor.clear();
dev_host_nbor.clear();
dev_host_numj.clear();
host_ilist.clear();
host_jlist.clear();
success=success && (host_nbor.alloc(_max_nbors*_max_host,*dev,
UCL_RW_OPTIMIZED)==UCL_SUCCESS);
success=success && (dev_host_nbor.alloc(_max_nbors*_max_host,
*dev,UCL_WRITE_ONLY)==UCL_SUCCESS);
success=success && (dev_host_numj.alloc(_max_host,*dev,
UCL_WRITE_ONLY)==UCL_SUCCESS);
success=success && (host_ilist.alloc(nt,*dev,UCL_NOT_PINNED)==UCL_SUCCESS);
if (!success)
return;
for (int i=0; i<nt; i++)
host_ilist[i]=i;
success=success && (host_jlist.alloc(_max_host,*dev,
UCL_NOT_PINNED)==UCL_SUCCESS);
if (!success)
return;
int *ptr=host_nbor.begin();
for (int i=0; i<_max_host; i++) {
host_jlist[i]=ptr;
ptr+=_max_nbors;
}
_c_bytes+=dev_host_nbor.row_bytes()+dev_host_numj.row_bytes();
}
if (_maxspecial>0) {
dev_nspecial.clear();
dev_special.clear();
dev_special_t.clear();
int at=_max_atoms+_max_host;
success=success && (dev_nspecial.alloc(3*at,*dev,
UCL_READ_ONLY)==UCL_SUCCESS);
success=success && (dev_special.alloc(_maxspecial*at,*dev,
UCL_READ_ONLY)==UCL_SUCCESS);
success=success && (dev_special_t.alloc(_maxspecial*at,*dev,
UCL_READ_ONLY)==UCL_SUCCESS);
_gpu_bytes+=dev_nspecial.row_bytes()+dev_special.row_bytes()+
dev_special_t.row_bytes();
}
_allocated=true;
}
void PairGPUNbor::clear() {
_gpu_bytes=0.0;
_cell_bytes=0.0;
_c_bytes=0.0;
if (_allocated) {
_allocated=false;
host_packed.clear();
host_acc.clear();
dev_nbor.clear();
dev_host_nbor.clear();
dev_packed.clear();
host_nbor.clear();
dev_host_numj.clear();
host_ilist.clear();
host_jlist.clear();
dev_nspecial.clear();
dev_special.clear();
dev_special_t.clear();
time_kernel.clear();
time_nbor.clear();
}
}
double PairGPUNbor::host_memory_usage() const {
if (_gpu_nbor) {
if (_gpu_host)
return host_nbor.row_bytes()*host_nbor.rows()+host_ilist.row_bytes()+
host_jlist.row_bytes();
else
return 0;
} else
return host_packed.row_bytes()*host_packed.rows()+host_acc.row_bytes()+
sizeof(PairGPUNbor);
}
void PairGPUNbor::get_host(const int inum, int *ilist, int *numj,
int **firstneigh, const int block_size) {
time_nbor.start();
UCL_H_Vec<int> ilist_view;
ilist_view.view(ilist,inum,*dev);
ucl_copy(dev_nbor,ilist_view,false);
UCL_D_Vec<int> nbor_offset;
UCL_H_Vec<int> host_offset;
int copy_count=0;
int ij_count=0;
int acc_count=0;
int dev_count=0;
int *h_ptr=host_packed.begin();
_nbor_pitch=inum;
for (int ii=0; ii<inum; ii++) {
int i=ilist[ii];
int nj=numj[i];
host_acc[ii]=nj;
host_acc[ii+inum]=acc_count;
acc_count+=nj;
int *jlist=firstneigh[i];
for (int jj=0; jj<nj; jj++) {
*h_ptr=jlist[jj];
h_ptr++;
ij_count++;
if (ij_count==IJ_SIZE) {
dev_nbor.sync();
host_offset.view_offset(IJ_SIZE*(copy_count%2),host_packed,IJ_SIZE);
nbor_offset.view_offset(dev_count,dev_packed,IJ_SIZE);
ucl_copy(nbor_offset,host_offset,true);
copy_count++;
ij_count=0;
dev_count+=IJ_SIZE;
h_ptr=host_packed.begin()+(IJ_SIZE*(copy_count%2));
}
}
}
if (ij_count!=0) {
dev_nbor.sync();
host_offset.view_offset(IJ_SIZE*(copy_count%2),host_packed,ij_count);
nbor_offset.view_offset(dev_count,dev_packed,ij_count);
ucl_copy(nbor_offset,host_offset,true);
}
UCL_D_Vec<int> acc_view;
acc_view.view_offset(inum,dev_nbor,inum*2);
ucl_copy(acc_view,host_acc,true);
time_nbor.stop();
if (_use_packing==false) {
time_kernel.start();
int GX=static_cast<int>(ceil(static_cast<double>(inum)/block_size));
_shared->k_nbor.set_size(GX,block_size);
_shared->k_nbor.run(&dev_nbor.begin(), &dev_packed.begin(), &inum);
time_kernel.stop();
}
}
template <class numtyp, class acctyp>
void PairGPUNbor::build_nbor_list(const int inum, const int host_inum,
const int nall,
PairGPUAtom<numtyp,acctyp> &atom,
double *sublo, double *subhi, int *tag,
int **nspecial, int **special, bool &success,
int &mn) {
const int nt=inum+host_inum;
if (_maxspecial>0) {
time_nbor.start();
UCL_H_Vec<int> view_nspecial, view_special, view_tag;
view_nspecial.view(nspecial[0],nt*3,*dev);
view_special.view(special[0],nt*_maxspecial,*dev);
view_tag.view(tag,nall,*dev);
ucl_copy(dev_nspecial,view_nspecial,nt*3,false);
ucl_copy(dev_special_t,view_special,nt*_maxspecial,false);
ucl_copy(atom.dev_tag,view_tag,nall,false);
time_nbor.stop();
time_nbor.add_to_total();
time_kernel.start();
const int b2x=_block_cell_2d;
const int b2y=_block_cell_2d;
const int g2x=static_cast<int>(ceil(static_cast<double>(_maxspecial)/b2x));
const int g2y=static_cast<int>(ceil(static_cast<double>(nt)/b2y));
_shared->k_transpose.set_size(g2x,g2y,b2x,b2y);
_shared->k_transpose.run(&dev_special.begin(),&dev_special_t.begin(),
&_maxspecial,&nt);
} else
time_kernel.start();
_nbor_pitch=inum;
_shared->neigh_tex.bind_float(atom.dev_x,4);
int ncellx, ncelly, ncellz, ncell_3d;
ncellx = static_cast<int>(ceil(((subhi[0] - sublo[0]) +
2.0*_cell_size)/_cell_size));
ncelly = static_cast<int>(ceil(((subhi[1] - sublo[1]) +
2.0*_cell_size)/_cell_size));
ncellz = static_cast<int>(ceil(((subhi[2] - sublo[2]) +
2.0*_cell_size)/_cell_size));
ncell_3d = ncellx * ncelly * ncellz;
UCL_D_Vec<int> cell_counts;
cell_counts.alloc(ncell_3d+1,dev_nbor);
_cell_bytes=cell_counts.row_bytes();
/* build cell list on GPU */
const int neigh_block=_block_cell_id;
const int GX=(int)ceil((float)nall/neigh_block);
const numtyp sublo0=static_cast<numtyp>(sublo[0]);
const numtyp sublo1=static_cast<numtyp>(sublo[1]);
const numtyp sublo2=static_cast<numtyp>(sublo[2]);
const numtyp subhi0=static_cast<numtyp>(subhi[0]);
const numtyp subhi1=static_cast<numtyp>(subhi[1]);
const numtyp subhi2=static_cast<numtyp>(subhi[2]);
const numtyp cell_size_cast=static_cast<numtyp>(_cell_size);
_shared->k_cell_id.set_size(GX,neigh_block);
_shared->k_cell_id.run(&atom.dev_x.begin(), &atom.dev_cell_id.begin(),
&atom.dev_particle_id.begin(),
&sublo0, &sublo1, &sublo2, &subhi0, &subhi1,
&subhi2, &cell_size_cast, &ncellx, &ncelly, &nall);
atom.sort_neighbor(nall);
/* calculate cell count */
_shared->k_cell_counts.set_size(GX,neigh_block);
_shared->k_cell_counts.run(&atom.dev_cell_id.begin(), &cell_counts.begin(),
&nall, &ncell_3d);
/* build the neighbor list */
const int cell_block=_block_nbor_build;
_shared->k_build_nbor.set_size(ncellx, ncelly*ncellz, cell_block, 1);
_shared->k_build_nbor.run(&atom.dev_x.begin(), &atom.dev_particle_id.begin(),
&cell_counts.begin(), &dev_nbor.begin(),
&dev_host_nbor.begin(), &dev_host_numj.begin(),
&_max_nbors,&cell_size_cast,
&ncellx, &ncelly, &ncellz, &inum, &nt, &nall);
/* Get the maximum number of nbors and realloc if necessary */
UCL_D_Vec<int> numj;
numj.view_offset(inum,dev_nbor,inum);
ucl_copy(host_acc,numj,inum,false);
if (nt>inum) {
UCL_H_Vec<int> host_offset;
host_offset.view_offset(inum,host_acc,nt-inum);
ucl_copy(host_offset,dev_host_numj,nt-inum,false);
}
mn=host_acc[0];
for (int i=1; i<nt; i++)
mn=std::max(mn,host_acc[i]);
if (mn>_max_nbors) {
mn=static_cast<int>(static_cast<double>(mn)*1.10);
dev_nbor.clear();
success=success && (dev_nbor.alloc((mn+1)*_max_atoms,atom.dev_cell_id,
UCL_READ_ONLY)==UCL_SUCCESS);
_gpu_bytes=dev_nbor.row_bytes();
if (_max_host>0) {
host_nbor.clear();
dev_host_nbor.clear();
success=success && (host_nbor.alloc(mn*_max_host,dev_nbor,
UCL_RW_OPTIMIZED)==UCL_SUCCESS);
success=success && (dev_host_nbor.alloc(mn*_max_host,
dev_nbor,UCL_WRITE_ONLY)==UCL_SUCCESS);
int *ptr=host_nbor.begin();
for (int i=0; i<_max_host; i++) {
host_jlist[i]=ptr;
ptr+=mn;
}
_gpu_bytes+=dev_host_nbor.row_bytes();
}
if (_alloc_packed) {
dev_packed.clear();
success=success && (dev_packed.alloc((mn+2)*_max_atoms,*dev,
UCL_READ_ONLY)==UCL_SUCCESS);
_gpu_bytes+=dev_packed.row_bytes();
}
if (!success)
return;
_max_nbors=mn;
time_kernel.stop();
time_kernel.add_to_total();
build_nbor_list(inum, host_inum, nall, atom, sublo, subhi, tag, nspecial,
special, success, mn);
return;
}
if (_maxspecial>0) {
const int GX2=static_cast<int>(ceil(static_cast<double>(nt)/cell_block));
_shared->k_special.set_size(GX2,cell_block);
_shared->k_special.run(&dev_nbor.begin(), &dev_host_nbor.begin(),
&dev_host_numj.begin(), &atom.dev_tag.begin(),
&dev_nspecial.begin(), &dev_special.begin(),
&inum, &nt, &_max_nbors);
}
time_kernel.stop();
time_nbor.start();
if (_gpu_host)
ucl_copy(host_nbor,dev_host_nbor,false);
time_nbor.stop();
}
template void PairGPUNbor::build_nbor_list<PRECISION,ACC_PRECISION>
(const int inum, const int host_inum, const int nall,
PairGPUAtom<PRECISION,ACC_PRECISION> &atom, double *sublo, double *subhi,
int *, int **, int **, bool &success, int &mn);

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