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lammps/lib/gpu/lal_dpd.cu
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lal_dpd.cu
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// **************************************************************************
// dpd.cu
// -------------------
// Trung Dac Nguyen (ORNL)
//
// Device code for acceleration of the dpd pair style
//
// __________________________________________________________________________
// This file is part of the LAMMPS Accelerator Library (LAMMPS_AL)
// __________________________________________________________________________
//
// begin : Jan 15, 2014
// email : nguyentd@ornl.gov
// ***************************************************************************/
#ifdef NV_KERNEL
#include "lal_aux_fun1.h"
#ifndef _DOUBLE_DOUBLE
texture<float4> pos_tex;
texture<float4> vel_tex;
#else
texture<int4,1> pos_tex;
texture<int4,1> vel_tex;
#endif
#else
#define pos_tex x_
#define vel_tex v_
#endif
#define EPSILON (numtyp)1.0e-10
//#define _USE_UNIFORM_SARU_LCG
//#define _USE_UNIFORM_SARU_TEA8
//#define _USE_GAUSSIAN_SARU_LCG
#if !defined(_USE_UNIFORM_SARU_LCG) && !defined(_USE_UNIFORM_SARU_TEA8) && !defined(_USE_GAUSSIAN_SARU_LCG)
#define _USE_UNIFORM_SARU_LCG
#endif
// References:
// 1. Y. Afshar, F. Schmid, A. Pishevar, S. Worley, Comput. Phys. Comm. 184 (2013), 1119–1128.
// 2. C. L. Phillips, J. A. Anderson, S. C. Glotzer, Comput. Phys. Comm. 230 (2011), 7191-7201.
// PRNG period = 3666320093*2^32 ~ 2^64 ~ 10^19
#define LCGA 0x4beb5d59 // Full period 32 bit LCG
#define LCGC 0x2600e1f7
#define oWeylPeriod 0xda879add // Prime period 3666320093
#define oWeylOffset 0x8009d14b
#define TWO_N32 0.232830643653869628906250e-9f /* 2^-32 */
// specifically implemented for steps = 1; high = 1.0; low = -1.0
// returns uniformly distributed random numbers u in [-1.0;1.0]
// using the inherent LCG, then multiply u with sqrt(3) to "match"
// with a normal random distribution.
// Afshar et al. mutlplies u in [-0.5;0.5] with sqrt(12)
// Curly brackets to make variables local to the scope.
#ifdef _USE_UNIFORM_SARU_LCG
#define SQRT3 (numtyp)1.7320508075688772935274463
#define saru(seed1, seed2, seed, timestep, randnum) { \
unsigned int seed3 = seed + timestep; \
seed3^=(seed1<<7)^(seed2>>6); \
seed2+=(seed1>>4)^(seed3>>15); \
seed1^=(seed2<<9)+(seed3<<8); \
seed3^=0xA5366B4D*((seed2>>11) ^ (seed1<<1)); \
seed2+=0x72BE1579*((seed1<<4) ^ (seed3>>16)); \
seed1^=0x3F38A6ED*((seed3>>5) ^ (((signed int)seed2)>>22)); \
seed2+=seed1*seed3; \
seed1+=seed3 ^ (seed2>>2); \
seed2^=((signed int)seed2)>>17; \
unsigned int state = 0x79dedea3*(seed1^(((signed int)seed1)>>14)); \
unsigned int wstate = (state + seed2) ^ (((signed int)state)>>8); \
state = state + (wstate*(wstate^0xdddf97f5)); \
wstate = 0xABCB96F7 + (wstate>>1); \
state = LCGA*state + LCGC; \
wstate = wstate + oWeylOffset+((((signed int)wstate)>>31) & oWeylPeriod); \
unsigned int v = (state ^ (state>>26)) + wstate; \
unsigned int s = (signed int)((v^(v>>20))*0x6957f5a7); \
randnum = SQRT3*(s*TWO_N32*(numtyp)2.0-(numtyp)1.0); \
}
#endif
// specifically implemented for steps = 1; high = 1.0; low = -1.0
// returns uniformly distributed random numbers u in [-1.0;1.0] using TEA8
// then multiply u with sqrt(3) to "match" with a normal random distribution
// Afshar et al. mutlplies u in [-0.5;0.5] with sqrt(12)
#ifdef _USE_UNIFORM_SARU_TEA8
#define SQRT3 (numtyp)1.7320508075688772935274463
#define k0 0xA341316C
#define k1 0xC8013EA4
#define k2 0xAD90777D
#define k3 0x7E95761E
#define delta 0x9e3779b9
#define rounds 8
#define saru(seed1, seed2, seed, timestep, randnum) { \
unsigned int seed3 = seed + timestep; \
seed3^=(seed1<<7)^(seed2>>6); \
seed2+=(seed1>>4)^(seed3>>15); \
seed1^=(seed2<<9)+(seed3<<8); \
seed3^=0xA5366B4D*((seed2>>11) ^ (seed1<<1)); \
seed2+=0x72BE1579*((seed1<<4) ^ (seed3>>16)); \
seed1^=0x3F38A6ED*((seed3>>5) ^ (((signed int)seed2)>>22)); \
seed2+=seed1*seed3; \
seed1+=seed3 ^ (seed2>>2); \
seed2^=((signed int)seed2)>>17; \
unsigned int state = 0x79dedea3*(seed1^(((signed int)seed1)>>14)); \
unsigned int wstate = (state + seed2) ^ (((signed int)state)>>8); \
state = state + (wstate*(wstate^0xdddf97f5)); \
wstate = 0xABCB96F7 + (wstate>>1); \
unsigned int sum = 0; \
for (int i=0; i < rounds; i++) { \
sum += delta; \
state += ((wstate<<4) + k0)^(wstate + sum)^((wstate>>5) + k1); \
wstate += ((state<<4) + k2)^(state + sum)^((state>>5) + k3); \
} \
unsigned int v = (state ^ (state>>26)) + wstate; \
unsigned int s = (signed int)((v^(v>>20))*0x6957f5a7); \
randnum = SQRT3*(s*TWO_N32*(numtyp)2.0-(numtyp)1.0); \
}
#endif
// specifically implemented for steps = 1; high = 1.0; low = -1.0
// returns two uniformly distributed random numbers r1 and r2 in [-1.0;1.0],
// and uses the polar method (Marsaglia's) to transform to a normal random value
// This is used to compared with CPU DPD using RandMars::gaussian()
#ifdef _USE_GAUSSIAN_SARU_LCG
#define saru(seed1, seed2, seed, timestep, randnum) { \
unsigned int seed3 = seed + timestep; \
seed3^=(seed1<<7)^(seed2>>6); \
seed2+=(seed1>>4)^(seed3>>15); \
seed1^=(seed2<<9)+(seed3<<8); \
seed3^=0xA5366B4D*((seed2>>11) ^ (seed1<<1)); \
seed2+=0x72BE1579*((seed1<<4) ^ (seed3>>16)); \
seed1^=0x3F38A6ED*((seed3>>5) ^ (((signed int)seed2)>>22)); \
seed2+=seed1*seed3; \
seed1+=seed3 ^ (seed2>>2); \
seed2^=((signed int)seed2)>>17; \
unsigned int state=0x12345678; \
unsigned int wstate=12345678; \
state = 0x79dedea3*(seed1^(((signed int)seed1)>>14)); \
wstate = (state + seed2) ^ (((signed int)state)>>8); \
state = state + (wstate*(wstate^0xdddf97f5)); \
wstate = 0xABCB96F7 + (wstate>>1); \
unsigned int v, s; \
numtyp r1, r2, rsq; \
while (1) { \
state = LCGA*state + LCGC; \
wstate = wstate + oWeylOffset+((((signed int)wstate)>>31) & oWeylPeriod); \
v = (state ^ (state>>26)) + wstate; \
s = (signed int)((v^(v>>20))*0x6957f5a7); \
r1 = s*TWO_N32*(numtyp)2.0-(numtyp)1.0; \
state = LCGA*state + LCGC; \
wstate = wstate + oWeylOffset+((((signed int)wstate)>>31) & oWeylPeriod); \
v = (state ^ (state>>26)) + wstate; \
s = (signed int)((v^(v>>20))*0x6957f5a7); \
r2 = s*TWO_N32*(numtyp)2.0-(numtyp)1.0; \
rsq = r1 * r1 + r2 * r2; \
if (rsq < (numtyp)1.0) break; \
} \
numtyp fac = ucl_sqrt((numtyp)-2.0*log(rsq)/rsq); \
randnum = r2*fac; \
}
#endif
__kernel void k_dpd(const __global numtyp4 *restrict x_,
const __global numtyp4 *restrict coeff,
const int lj_types,
const __global numtyp *restrict sp_lj,
const __global int * dev_nbor,
const __global int * dev_packed,
__global acctyp4 *restrict ans,
__global acctyp *restrict engv,
const int eflag, const int vflag, const int inum,
const int nbor_pitch,
const __global numtyp4 *restrict v_,
const __global numtyp *restrict cutsq,
const numtyp dtinvsqrt, const int seed,
const int timestep, const int tstat_only,
const int t_per_atom) {
int tid, ii, offset;
atom_info(t_per_atom,ii,tid,offset);
acctyp energy=(acctyp)0;
acctyp4 f;
f.x=(acctyp)0; f.y=(acctyp)0; f.z=(acctyp)0;
acctyp virial[6];
for (int i=0; i<6; i++)
virial[i]=(acctyp)0;
if (ii<inum) {
int nbor, nbor_end;
int i, numj;
__local int n_stride;
nbor_info(dev_nbor,dev_packed,nbor_pitch,t_per_atom,ii,offset,i,numj,
n_stride,nbor_end,nbor);
numtyp4 ix; fetch4(ix,i,pos_tex); //x_[i];
int itype=ix.w;
numtyp4 iv; fetch4(iv,i,vel_tex); //v_[i];
int itag=iv.w;
numtyp factor_dpd;
for ( ; nbor<nbor_end; nbor+=n_stride) {
int j=dev_packed[nbor];
factor_dpd = sp_lj[sbmask(j)];
j &= NEIGHMASK;
numtyp4 jx; fetch4(jx,j,pos_tex); //x_[j];
int jtype=jx.w;
numtyp4 jv; fetch4(jv,j,vel_tex); //v_[j];
int jtag=jv.w;
// Compute r12
numtyp delx = ix.x-jx.x;
numtyp dely = ix.y-jx.y;
numtyp delz = ix.z-jx.z;
numtyp rsq = delx*delx+dely*dely+delz*delz;
int mtype=itype*lj_types+jtype;
if (rsq<cutsq[mtype]) {
numtyp r=ucl_sqrt(rsq);
if (r < EPSILON) continue;
numtyp rinv=ucl_recip(r);
numtyp delvx = iv.x - jv.x;
numtyp delvy = iv.y - jv.y;
numtyp delvz = iv.z - jv.z;
numtyp dot = delx*delvx + dely*delvy + delz*delvz;
numtyp wd = (numtyp)1.0 - r/coeff[mtype].w;
unsigned int tag1=itag, tag2=jtag;
if (tag1 > tag2) {
tag1 = jtag; tag2 = itag;
}
numtyp randnum = (numtyp)0.0;
saru(tag1, tag2, seed, timestep, randnum);
// conservative force = a0 * wd, or 0 if tstat only
// drag force = -gamma * wd^2 * (delx dot delv) / r
// random force = sigma * wd * rnd * dtinvsqrt;
numtyp force = (numtyp)0.0;
if (!tstat_only) force = coeff[mtype].x*wd;
force -= coeff[mtype].y*wd*wd*dot*rinv;
force += coeff[mtype].z*wd*randnum*dtinvsqrt;
force*=factor_dpd*rinv;
f.x+=delx*force;
f.y+=dely*force;
f.z+=delz*force;
if (eflag>0) {
// unshifted eng of conservative term:
// evdwl = -a0[itype][jtype]*r * (1.0-0.5*r/cut[itype][jtype]);
// eng shifted to 0.0 at cutoff
numtyp e = (numtyp)0.5*coeff[mtype].x*coeff[mtype].w * wd*wd;
energy+=factor_dpd*e;
}
if (vflag>0) {
virial[0] += delx*delx*force;
virial[1] += dely*dely*force;
virial[2] += delz*delz*force;
virial[3] += delx*dely*force;
virial[4] += delx*delz*force;
virial[5] += dely*delz*force;
}
}
} // for nbor
store_answers(f,energy,virial,ii,inum,tid,t_per_atom,offset,eflag,vflag,
ans,engv);
} // if ii
}
__kernel void k_dpd_fast(const __global numtyp4 *restrict x_,
const __global numtyp4 *restrict coeff_in,
const __global numtyp *restrict sp_lj_in,
const __global int * dev_nbor,
const __global int * dev_packed,
__global acctyp4 *restrict ans,
__global acctyp *restrict engv,
const int eflag, const int vflag, const int inum,
const int nbor_pitch,
const __global numtyp4 *restrict v_,
const __global numtyp *restrict cutsq,
const numtyp dtinvsqrt, const int seed,
const int timestep, const int tstat_only,
const int t_per_atom) {
int tid, ii, offset;
atom_info(t_per_atom,ii,tid,offset);
__local numtyp4 coeff[MAX_SHARED_TYPES*MAX_SHARED_TYPES];
__local numtyp sp_lj[4];
if (tid<4)
sp_lj[tid]=sp_lj_in[tid];
if (tid<MAX_SHARED_TYPES*MAX_SHARED_TYPES) {
coeff[tid]=coeff_in[tid];
}
acctyp energy=(acctyp)0;
acctyp4 f;
f.x=(acctyp)0; f.y=(acctyp)0; f.z=(acctyp)0;
acctyp virial[6];
for (int i=0; i<6; i++)
virial[i]=(acctyp)0;
__syncthreads();
if (ii<inum) {
int nbor, nbor_end;
int i, numj;
__local int n_stride;
nbor_info(dev_nbor,dev_packed,nbor_pitch,t_per_atom,ii,offset,i,numj,
n_stride,nbor_end,nbor);
numtyp4 ix; fetch4(ix,i,pos_tex); //x_[i];
int iw=ix.w;
int itype=fast_mul((int)MAX_SHARED_TYPES,iw);
numtyp4 iv; fetch4(iv,i,vel_tex); //v_[i];
int itag=iv.w;
numtyp factor_dpd;
for ( ; nbor<nbor_end; nbor+=n_stride) {
int j=dev_packed[nbor];
factor_dpd = sp_lj[sbmask(j)];
j &= NEIGHMASK;
numtyp4 jx; fetch4(jx,j,pos_tex); //x_[j];
int mtype=itype+jx.w;
numtyp4 jv; fetch4(jv,j,vel_tex); //v_[j];
int jtag=jv.w;
// Compute r12
numtyp delx = ix.x-jx.x;
numtyp dely = ix.y-jx.y;
numtyp delz = ix.z-jx.z;
numtyp rsq = delx*delx+dely*dely+delz*delz;
if (rsq<cutsq[mtype]) {
numtyp r=ucl_sqrt(rsq);
if (r < EPSILON) continue;
numtyp rinv=ucl_recip(r);
numtyp delvx = iv.x - jv.x;
numtyp delvy = iv.y - jv.y;
numtyp delvz = iv.z - jv.z;
numtyp dot = delx*delvx + dely*delvy + delz*delvz;
numtyp wd = (numtyp)1.0 - r/coeff[mtype].w;
unsigned int tag1=itag, tag2=jtag;
if (tag1 > tag2) {
tag1 = jtag; tag2 = itag;
}
numtyp randnum = (numtyp)0.0;
saru(tag1, tag2, seed, timestep, randnum);
// conservative force = a0 * wd, or 0 if tstat only
// drag force = -gamma * wd^2 * (delx dot delv) / r
// random force = sigma * wd * rnd * dtinvsqrt;
numtyp force = (numtyp)0.0;
if (!tstat_only) force = coeff[mtype].x*wd;
force -= coeff[mtype].y*wd*wd*dot*rinv;
force += coeff[mtype].z*wd*randnum*dtinvsqrt;
force*=factor_dpd*rinv;
f.x+=delx*force;
f.y+=dely*force;
f.z+=delz*force;
if (eflag>0) {
// unshifted eng of conservative term:
// evdwl = -a0[itype][jtype]*r * (1.0-0.5*r/cut[itype][jtype]);
// eng shifted to 0.0 at cutoff
numtyp e = (numtyp)0.5*coeff[mtype].x*coeff[mtype].w * wd*wd;
energy+=factor_dpd*e;
}
if (vflag>0) {
virial[0] += delx*delx*force;
virial[1] += dely*dely*force;
virial[2] += delz*delz*force;
virial[3] += delx*dely*force;
virial[4] += delx*delz*force;
virial[5] += dely*delz*force;
}
}
} // for nbor
store_answers(f,energy,virial,ii,inum,tid,t_per_atom,offset,eflag,vflag,
ans,engv);
} // if ii
}
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