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pair_lj_cut_intel.cpp
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Fri, May 10, 17:51

pair_lj_cut_intel.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
This software is distributed under the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Contributing author: W. Michael Brown (Intel)
------------------------------------------------------------------------- */
#include "math.h"
#include "pair_lj_cut_intel.h"
#include "atom.h"
#include "comm.h"
#include "force.h"
#include "memory.h"
#include "modify.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "neigh_request.h"
#include "suffix.h"
using namespace LAMMPS_NS;
#define FC_PACKED1_T typename ForceConst<flt_t>::fc_packed1
#define FC_PACKED2_T typename ForceConst<flt_t>::fc_packed2
/* ---------------------------------------------------------------------- */
PairLJCutIntel::PairLJCutIntel(LAMMPS *lmp) :
PairLJCut(lmp)
{
suffix_flag |= Suffix::INTEL;
respa_enable = 0;
cut_respa = NULL;
}
/* ---------------------------------------------------------------------- */
void PairLJCutIntel::compute(int eflag, int vflag)
{
if (fix->precision() == FixIntel::PREC_MODE_MIXED)
compute<float,double>(eflag, vflag, fix->get_mixed_buffers(),
force_const_single);
else if (fix->precision() == FixIntel::PREC_MODE_DOUBLE)
compute<double,double>(eflag, vflag, fix->get_double_buffers(),
force_const_double);
else
compute<float,float>(eflag, vflag, fix->get_single_buffers(),
force_const_single);
fix->balance_stamp();
vflag_fdotr = 0;
}
template <class flt_t, class acc_t>
void PairLJCutIntel::compute(int eflag, int vflag,
IntelBuffers<flt_t,acc_t> *buffers,
const ForceConst<flt_t> &fc)
{
if (eflag || vflag) {
ev_setup(eflag, vflag);
} else evflag = vflag_fdotr = 0;
const int inum = list->inum;
const int nthreads = comm->nthreads;
const int host_start = fix->host_start_pair();
const int offload_end = fix->offload_end_pair();
const int ago = neighbor->ago;
if (ago != 0 && fix->separate_buffers() == 0) {
fix->start_watch(TIME_PACK);
if (ago != 0) {
#if defined(_OPENMP)
#pragma omp parallel default(none) shared(eflag,vflag,buffers,fc)
#endif
{
int ifrom, ito, tid;
IP_PRE_omp_range_id_align(ifrom, ito, tid, atom->nlocal + atom->nghost,
nthreads, sizeof(ATOM_T));
buffers->thr_pack(ifrom,ito,ago);
}
}
fix->stop_watch(TIME_PACK);
}
if (evflag || vflag_fdotr) {
int ovflag = 0;
if (vflag_fdotr) ovflag = 2;
else if (vflag) ovflag = 1;
if (eflag) {
if (force->newton_pair) {
eval<1,1,1>(1, ovflag, buffers, fc, 0, offload_end);
eval<1,1,1>(0, ovflag, buffers, fc, host_start, inum);
} else {
eval<1,1,0>(1, ovflag, buffers, fc, 0, offload_end);
eval<1,1,0>(0, ovflag, buffers, fc, host_start, inum);
}
} else {
if (force->newton_pair) {
eval<1,0,1>(1, ovflag, buffers, fc, 0, offload_end);
eval<1,0,1>(0, ovflag, buffers, fc, host_start, inum);
} else {
eval<1,0,0>(1, ovflag, buffers, fc, 0, offload_end);
eval<1,0,0>(0, ovflag, buffers, fc, host_start, inum);
}
}
} else {
if (force->newton_pair) {
eval<0,0,1>(1, 0, buffers, fc, 0, offload_end);
eval<0,0,1>(0, 0, buffers, fc, host_start, inum);
} else {
eval<0,0,0>(1, 0, buffers, fc, 0, offload_end);
eval<0,0,0>(0, 0, buffers, fc, host_start, inum);
}
}
}
template <int EVFLAG, int EFLAG, int NEWTON_PAIR, class flt_t, class acc_t>
void PairLJCutIntel::eval(const int offload, const int vflag,
IntelBuffers<flt_t,acc_t> *buffers,
const ForceConst<flt_t> &fc,
const int astart, const int aend)
{
const int inum = aend - astart;
if (inum == 0) return;
int nlocal, nall, minlocal;
fix->get_buffern(offload, nlocal, nall, minlocal);
const int ago = neighbor->ago;
IP_PRE_pack_separate_buffers(fix, buffers, ago, offload, nlocal, nall);
ATOM_T * _noalias const x = buffers->get_x(offload);
const int * _noalias const numneigh = list->numneigh;
const int * _noalias const cnumneigh = buffers->cnumneigh(list);
const int * _noalias const firstneigh = buffers->firstneigh(list);
const flt_t * _noalias const special_lj = fc.special_lj;
const FC_PACKED1_T * _noalias const ljc12o = fc.ljc12o[0];
const FC_PACKED2_T * _noalias const lj34 = fc.lj34[0];
const int ntypes = atom->ntypes + 1;
const int eatom = this->eflag_atom;
// Determine how much data to transfer
int x_size, q_size, f_stride, ev_size, separate_flag;
IP_PRE_get_transfern(ago, NEWTON_PAIR, EVFLAG, EFLAG, vflag,
buffers, offload, fix, separate_flag,
x_size, q_size, ev_size, f_stride);
int tc;
FORCE_T * _noalias f_start;
acc_t * _noalias ev_global;
IP_PRE_get_buffers(offload, buffers, fix, tc, f_start, ev_global);
const int nthreads = tc;
int *overflow = fix->get_off_overflow_flag();
{
#ifdef __MIC__
*timer_compute = MIC_Wtime();
#endif
IP_PRE_repack_for_offload(NEWTON_PAIR, separate_flag, nlocal, nall,
f_stride, x, 0);
acc_t oevdwl, ov0, ov1, ov2, ov3, ov4, ov5;
if (EVFLAG) {
oevdwl = (acc_t)0;
if (vflag) ov0 = ov1 = ov2 = ov3 = ov4 = ov5 = (acc_t)0;
}
// loop over neighbors of my atoms
#if defined(_OPENMP)
#pragma omp parallel default(none) \
shared(f_start,f_stride,nlocal,nall,minlocal) \
reduction(+:oevdwl,ov0,ov1,ov2,ov3,ov4,ov5)
#endif
{
int iifrom, iito, tid;
IP_PRE_omp_range_id(iifrom, iito, tid, inum, nthreads);
iifrom += astart;
iito += astart;
FORCE_T * _noalias const f = f_start - minlocal + (tid * f_stride);
memset(f + minlocal, 0, f_stride * sizeof(FORCE_T));
for (int i = iifrom; i < iito; ++i) {
const int itype = x[i].w;
const int ptr_off = itype * ntypes;
const FC_PACKED1_T * _noalias const ljc12oi = ljc12o + ptr_off;
const FC_PACKED2_T * _noalias const lj34i = lj34 + ptr_off;
const int * _noalias const jlist = firstneigh + cnumneigh[i];
const int jnum = numneigh[i];
acc_t fxtmp, fytmp, fztmp, fwtmp;
acc_t sevdwl, sv0, sv1, sv2, sv3, sv4, sv5;
const flt_t xtmp = x[i].x;
const flt_t ytmp = x[i].y;
const flt_t ztmp = x[i].z;
fxtmp = fytmp = fztmp = (acc_t)0;
if (EVFLAG) {
if (EFLAG) fwtmp = sevdwl = (acc_t)0;
if (vflag==1) sv0 = sv1 = sv2 = sv3 = sv4 = sv5 = (acc_t)0;
}
#if defined(LMP_SIMD_COMPILER)
#pragma vector aligned
#pragma simd reduction(+:fxtmp, fytmp, fztmp, fwtmp, sevdwl, \
sv0, sv1, sv2, sv3, sv4, sv5)
#endif
for (int jj = 0; jj < jnum; jj++) {
flt_t forcelj, evdwl;
forcelj = evdwl = (flt_t)0.0;
const int sbindex = jlist[jj] >> SBBITS & 3;
const int j = jlist[jj] & NEIGHMASK;
const flt_t delx = xtmp - x[j].x;
const flt_t dely = ytmp - x[j].y;
const flt_t delz = ztmp - x[j].z;
const int jtype = x[j].w;
const flt_t rsq = delx * delx + dely * dely + delz * delz;
#ifdef INTEL_VMASK
if (rsq < ljc12oi[jtype].cutsq) {
#endif
flt_t factor_lj = special_lj[sbindex];
flt_t r2inv = 1.0 / rsq;
flt_t r6inv = r2inv * r2inv * r2inv;
#ifndef INTEL_VMASK
if (rsq > ljc12oi[jtype].cutsq) r6inv = (flt_t)0.0;
#endif
forcelj = r6inv * (ljc12oi[jtype].lj1 * r6inv - ljc12oi[jtype].lj2);
flt_t fpair = factor_lj * forcelj * r2inv;
fxtmp += delx * fpair;
fytmp += dely * fpair;
fztmp += delz * fpair;
if (NEWTON_PAIR || j < nlocal) {
f[j].x -= delx * fpair;
f[j].y -= dely * fpair;
f[j].z -= delz * fpair;
}
if (EVFLAG) {
flt_t ev_pre = (flt_t)0;
if (NEWTON_PAIR || i<nlocal)
ev_pre += (flt_t)0.5;
if (NEWTON_PAIR || j<nlocal)
ev_pre += (flt_t)0.5;
if (EFLAG) {
evdwl = r6inv * (lj34i[jtype].lj3 * r6inv-lj34i[jtype].lj4) -
ljc12oi[jtype].offset;
evdwl *= factor_lj;
sevdwl += ev_pre*evdwl;
if (eatom) {
if (NEWTON_PAIR || i < nlocal)
fwtmp += 0.5 * evdwl;
if (NEWTON_PAIR || j < nlocal)
f[j].w += 0.5 * evdwl;
}
}
IP_PRE_ev_tally_nbor(vflag, ev_pre, fpair,
delx, dely, delz);
}
#ifdef INTEL_VMASK
} // if rsq
#endif
} // for jj
f[i].x += fxtmp;
f[i].y += fytmp;
f[i].z += fztmp;
IP_PRE_ev_tally_atom(EVFLAG, EFLAG, vflag, f, fwtmp);
} // for ii
#if defined(_OPENMP)
#pragma omp barrier
#endif
IP_PRE_fdotr_acc_force(NEWTON_PAIR, EVFLAG, EFLAG, vflag, eatom, nall,
nlocal, minlocal, nthreads, f_start, f_stride,
x);
} // end omp
if (EVFLAG) {
if (EFLAG) {
ev_global[0] = oevdwl;
ev_global[1] = (acc_t)0.0;
}
if (vflag) {
ev_global[2] = ov0;
ev_global[3] = ov1;
ev_global[4] = ov2;
ev_global[5] = ov3;
ev_global[6] = ov4;
ev_global[7] = ov5;
}
}
#ifdef __MIC__
*timer_compute = MIC_Wtime() - *timer_compute;
#endif
} // end offload
if (offload)
fix->stop_watch(TIME_OFFLOAD_LATENCY);
else
fix->stop_watch(TIME_HOST_PAIR);
if (EVFLAG)
fix->add_result_array(f_start, ev_global, offload, eatom);
else
fix->add_result_array(f_start, 0, offload);
}
/* ---------------------------------------------------------------------- */
void PairLJCutIntel::init_style()
{
PairLJCut::init_style();
neighbor->requests[neighbor->nrequest-1]->intel = 1;
int ifix = modify->find_fix("package_intel");
if (ifix < 0)
error->all(FLERR,
"The 'package intel' command is required for /intel styles");
fix = static_cast<FixIntel *>(modify->fix[ifix]);
fix->pair_init_check();
#ifdef _LMP_INTEL_OFFLOAD
if (fix->offload_balance() != 0.0)
error->all(FLERR,
"Offload for lj/cut/intel is not yet available. Set balance to 0.");
#endif
if (fix->precision() == FixIntel::PREC_MODE_MIXED)
pack_force_const(force_const_single, fix->get_mixed_buffers());
else if (fix->precision() == FixIntel::PREC_MODE_DOUBLE)
pack_force_const(force_const_double, fix->get_double_buffers());
else
pack_force_const(force_const_single, fix->get_single_buffers());
}
/* ---------------------------------------------------------------------- */
template <class flt_t, class acc_t>
void PairLJCutIntel::pack_force_const(ForceConst<flt_t> &fc,
IntelBuffers<flt_t,acc_t> *buffers)
{
int tp1 = atom->ntypes + 1;
fc.set_ntypes(tp1,memory,_cop);
buffers->set_ntypes(tp1);
flt_t **cutneighsq = buffers->get_cutneighsq();
// Repeat cutsq calculation because done after call to init_style
double cut, cutneigh;
for (int i = 1; i <= atom->ntypes; i++) {
for (int j = i; j <= atom->ntypes; j++) {
if (setflag[i][j] != 0 || (setflag[i][i] != 0 && setflag[j][j] != 0)) {
cut = init_one(i,j);
cutneigh = cut + neighbor->skin;
cutsq[i][j] = cutsq[j][i] = cut*cut;
cutneighsq[i][j] = cutneighsq[j][i] = cutneigh * cutneigh;
}
}
}
for (int i = 0; i < 4; i++) {
fc.special_lj[i] = force->special_lj[i];
fc.special_lj[0] = 1.0;
}
for (int i = 0; i < tp1; i++) {
for (int j = 0; j < tp1; j++) {
fc.ljc12o[i][j].lj1 = lj1[i][j];
fc.ljc12o[i][j].lj2 = lj2[i][j];
fc.lj34[i][j].lj3 = lj3[i][j];
fc.lj34[i][j].lj4 = lj4[i][j];
fc.ljc12o[i][j].cutsq = cutsq[i][j];
fc.ljc12o[i][j].offset = offset[i][j];
}
}
}
/* ---------------------------------------------------------------------- */
template <class flt_t>
void PairLJCutIntel::ForceConst<flt_t>::set_ntypes(const int ntypes,
Memory *memory,
const int cop) {
if (ntypes != _ntypes) {
if (_ntypes > 0) {
fc_packed1 *oljc12o = ljc12o[0];
fc_packed2 *olj34 = lj34[0];
_memory->destroy(oljc12o);
_memory->destroy(olj34);
}
if (ntypes > 0) {
_cop = cop;
memory->create(ljc12o,ntypes,ntypes,"fc.c12o");
memory->create(lj34,ntypes,ntypes,"fc.lj34");
}
}
_ntypes = ntypes;
_memory = memory;
}

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