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39 #include "gromacs/legacyheaders/types/simple.h"
40 #include "gromacs/legacyheaders/typedefs.h"
41 #include "gromacs/legacyheaders/force.h"
43 #include "gromacs/math/utilities.h"
44 #include "gromacs/math/vec.h"
45 #include "gromacs/pbcutil/ishift.h"
47 #include "nbnxn_kernel_gpu_ref.h"
48 #include "../nbnxn_consts.h"
49 #include "nbnxn_kernel_common.h"
50 #include "gromacs/mdlib/nb_verlet.h"
52 #define NCL_PER_SUPERCL (NBNXN_GPU_NCLUSTER_PER_SUPERCLUSTER)
53 #define CL_SIZE (NBNXN_GPU_CLUSTER_SIZE)
56 nbnxn_kernel_gpu_ref(const nbnxn_pairlist_t *nbl,
57 const nbnxn_atomdata_t *nbat,
58 const interaction_const_t *iconst,
67 const nbnxn_sci_t *nbln;
71 const real *Ftab = NULL;
72 real rcut2, rvdw2, rlist2;
78 int cj4_ind0, cj4_ind1, cj4_ind;
80 int ic, jc, ia, ja, is, ifs, js, jfs, im, jm;
84 real fscal, tx, ty, tz;
87 real qq, vcoul = 0, krsq, vctot;
93 real Vvdw_rep, Vvdw_disp;
94 real ix, iy, iz, fix, fiy, fiz;
96 real dx, dy, dz, rsq, rinv;
99 real c6, c12, cexp1, cexp2, br;
100 const real * shiftvec;
104 const nbnxn_excl_t *excl[2];
106 int npair_tot, npair;
107 int nhwu, nhwu_pruned;
109 if (nbl->na_ci != CL_SIZE)
111 gmx_fatal(FARGS, "The neighborlist cluster size in the GPU reference kernel is %d, expected it to be %d", nbl->na_ci, CL_SIZE);
114 if (clearF == enbvClearFYes)
119 bEner = (force_flags & GMX_FORCE_ENERGY);
121 bEwald = EEL_FULL(iconst->eeltype);
124 Ftab = iconst->tabq_coul_F;
127 rcut2 = iconst->rcoulomb*iconst->rcoulomb;
128 rvdw2 = iconst->rvdw*iconst->rvdw;
130 rlist2 = nbl->rlist*nbl->rlist;
133 facel = iconst->epsfac;
134 shiftvec = shift_vec[0];
135 vdwparam = nbat->nbfp;
144 for (n = 0; n < nbl->nsci; n++)
148 ish3 = 3*nbln->shift;
149 shX = shiftvec[ish3];
150 shY = shiftvec[ish3+1];
151 shZ = shiftvec[ish3+2];
152 cj4_ind0 = nbln->cj4_ind_start;
153 cj4_ind1 = nbln->cj4_ind_end;
158 if (nbln->shift == CENTRAL &&
159 nbl->cj4[cj4_ind0].cj[0] == sci*NCL_PER_SUPERCL)
161 /* we have the diagonal:
162 * add the charge self interaction energy term
164 for (im = 0; im < NCL_PER_SUPERCL; im++)
166 ci = sci*NCL_PER_SUPERCL + im;
167 for (ic = 0; ic < CL_SIZE; ic++)
169 ia = ci*CL_SIZE + ic;
170 iq = x[ia*nbat->xstride+3];
176 vctot *= -facel*0.5*iconst->c_rf;
180 /* last factor 1/sqrt(pi) */
181 vctot *= -facel*iconst->ewaldcoeff_q*M_1_SQRTPI;
185 for (cj4_ind = cj4_ind0; (cj4_ind < cj4_ind1); cj4_ind++)
187 excl[0] = &nbl->excl[nbl->cj4[cj4_ind].imei[0].excl_ind];
188 excl[1] = &nbl->excl[nbl->cj4[cj4_ind].imei[1].excl_ind];
190 for (jm = 0; jm < NBNXN_GPU_JGROUP_SIZE; jm++)
192 cj = nbl->cj4[cj4_ind].cj[jm];
194 for (im = 0; im < NCL_PER_SUPERCL; im++)
196 /* We're only using the first imask,
197 * but here imei[1].imask is identical.
199 if ((nbl->cj4[cj4_ind].imei[0].imask >> (jm*NCL_PER_SUPERCL+im)) & 1)
201 gmx_bool within_rlist;
203 ci = sci*NCL_PER_SUPERCL + im;
205 within_rlist = FALSE;
207 for (ic = 0; ic < CL_SIZE; ic++)
209 ia = ci*CL_SIZE + ic;
211 is = ia*nbat->xstride;
212 ifs = ia*nbat->fstride;
217 nti = ntype*2*type[ia];
223 for (jc = 0; jc < CL_SIZE; jc++)
225 ja = cj*CL_SIZE + jc;
227 if (nbln->shift == CENTRAL &&
228 ci == cj && ja <= ia)
233 int_bit = ((excl[jc>>2]->pair[(jc & 3)*CL_SIZE+ic] >> (jm*NCL_PER_SUPERCL+im)) & 1);
235 js = ja*nbat->xstride;
236 jfs = ja*nbat->fstride;
243 rsq = dx*dx + dy*dy + dz*dz;
253 if (type[ia] != ntype-1 && type[ja] != ntype-1)
258 /* avoid NaN for excluded pairs at r=0 */
259 rsq += (1.0 - int_bit)*NBNXN_AVOID_SING_R2_INC;
261 rinv = gmx_invsqrt(rsq);
269 krsq = iconst->k_rf*rsq;
270 fscal = qq*(int_bit*rinv - 2*krsq)*rinvsq;
273 vcoul = qq*(int_bit*rinv + krsq - iconst->c_rf);
279 rt = r*iconst->tabq_scale;
283 fexcl = (1 - eps)*Ftab[n0] + eps*Ftab[n0+1];
285 fscal = qq*(int_bit*rinvsq - fexcl)*rinv;
289 vcoul = qq*((int_bit - gmx_erf(iconst->ewaldcoeff_q*r))*rinv - int_bit*iconst->sh_ewald);
295 tj = nti + 2*type[ja];
297 /* Vanilla Lennard-Jones cutoff */
299 c12 = vdwparam[tj+1];
301 rinvsix = int_bit*rinvsq*rinvsq*rinvsq;
302 Vvdw_disp = c6*rinvsix;
303 Vvdw_rep = c12*rinvsix*rinvsix;
304 fscal += (Vvdw_rep - Vvdw_disp)*rinvsq;
311 (Vvdw_rep - int_bit*c12*iconst->sh_invrc6*iconst->sh_invrc6)/12 -
312 (Vvdw_disp - int_bit*c6*iconst->sh_invrc6)/6;
330 fshift[ish3] = fshift[ish3] + fix;
331 fshift[ish3+1] = fshift[ish3+1] + fiy;
332 fshift[ish3+2] = fshift[ish3+2] + fiz;
334 /* Count in half work-units.
335 * In CUDA one work-unit is 2 warps.
337 if ((ic+1) % (CL_SIZE/2) == 0)
347 within_rlist = FALSE;
359 Vc[ggid] = Vc[ggid] + vctot;
360 Vvdw[ggid] = Vvdw[ggid] + Vvdwtot;
366 fprintf(debug, "number of half %dx%d atom pairs: %d after pruning: %d fraction %4.2f\n",
367 nbl->na_ci, nbl->na_ci,
368 nhwu, nhwu_pruned, nhwu_pruned/(double)nhwu);
369 fprintf(debug, "generic kernel pair interactions: %d\n",
370 nhwu*nbl->na_ci/2*nbl->na_ci);
371 fprintf(debug, "generic kernel post-prune pair interactions: %d\n",
372 nhwu_pruned*nbl->na_ci/2*nbl->na_ci);
373 fprintf(debug, "generic kernel non-zero pair interactions: %d\n",
375 fprintf(debug, "ratio non-zero/post-prune pair interactions: %4.2f\n",
376 npair_tot/(double)(nhwu_pruned*nbl->na_ci/2*nbl->na_ci));