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fft3d_cuda.cpp
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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
Original Version:
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
See the README file in the top-level LAMMPS directory.
-----------------------------------------------------------------------
USER-CUDA Package and associated modifications:
https://sourceforge.net/projects/lammpscuda/
Christian Trott, christian.trott@tu-ilmenau.de
Lars Winterfeld, lars.winterfeld@tu-ilmenau.de
Theoretical Physics II, University of Technology Ilmenau, Germany
See the README file in the USER-CUDA directory.
This software is distributed under the GNU General Public License.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
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: Jim Shepherd (GA Tech) added SGI SCSL support
------------------------------------------------------------------------- */
#include "mpi.h"
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include "fft3d_cuda.h"
#include "fft3d_cuda_cu.h"
#include "remap.h"
#include <ctime>
#include "cuda_wrapper_cu.h"
#ifdef FFT_CUFFT
#endif
#define MIN(A,B) ((A) < (B)) ? (A) : (B)
#define MAX(A,B) ((A) > (B)) ? (A) : (B)
/* ----------------------------------------------------------------------
Data layout for 3d FFTs:
data set of Nfast x Nmid x Nslow elements is owned by P procs
on input, each proc owns a subsection of the elements
on output, each proc will own a (possibly different) subsection
my subsection must not overlap with any other proc's subsection,
i.e. the union of all proc's input (or output) subsections must
exactly tile the global Nfast x Nmid x Nslow data set
when called from C, all subsection indices are
C-style from 0 to N-1 where N = Nfast or Nmid or Nslow
when called from F77, all subsection indices are
F77-style from 1 to N where N = Nfast or Nmid or Nslow
a proc can own 0 elements on input or output
by specifying hi index < lo index
on both input and output, data is stored contiguously on a processor
with a fast-varying, mid-varying, and slow-varying index
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Perform 3d FFT
Arguments:
in starting address of input data on this proc
out starting address of where output data for this proc
will be placed (can be same as in)
flag 1 for forward FFT, -1 for inverse FFT
plan plan returned by previous call to fft_3d_create_plan
------------------------------------------------------------------------- */
void fft_3d_cuda(FFT_DATA *in, FFT_DATA *out, int flag, struct fft_plan_3d *plan)
{
#ifdef FFT_CUFFT
plan->iterate++;
timespec starttime,starttime2;
timespec endtime,endtime2;
int i,total,length,offset,num;
double norm;
FFT_DATA *data,*copy;
// system specific constants
// pre-remap to prepare for 1st FFTs if needed
// copy = loc for remap result
int nprocs=plan->nprocs;
if(nprocs>1)
{
if(plan->init)
clock_gettime(CLOCK_REALTIME,&starttime);
if (plan->pre_plan) {
if (plan->pre_target == 0) copy = out;
else copy = plan->copy;
if(plan->init) remap_3d((double *) in, (double *) out, (double *) plan->scratch,plan->pre_plan);
data = out;
}
else
data = in;
}
cufftResult retvalc;
if(plan->init)
{
if(nprocs>1)
{
if(sizeof(FFT_FLOAT)==sizeof(double))cudaMemcpy((void*) (plan->cudata2), (void*) data, plan->cudatasize/2,cudaMemcpyHostToDevice);
if(sizeof(FFT_FLOAT)==sizeof(float)) cudaMemcpy((void*) (plan->cudata2), (void*) data, plan->cudatasize,cudaMemcpyHostToDevice);
initfftdata((double*)plan->cudata2,(FFT_FLOAT*)plan->cudata,plan->nfast,plan->nmid,plan->nslow);
}
}
if (flag == -1)
{
retvalc=cufft(plan->plan_3d, plan->cudata, plan->cudata2,CUFFT_FORWARD);
}
else
{
retvalc=cufft(plan->plan_3d, plan->cudata, plan->cudata2,CUFFT_INVERSE);
}
if(retvalc!=CUFFT_SUCCESS) {printf("ErrorCUFFT: %i\n",retvalc);exit(EXIT_FAILURE);}
FFTsyncthreads();
#endif
}
/* ----------------------------------------------------------------------
Create plan for performing a 3d FFT
Arguments:
comm MPI communicator for the P procs which own the data
nfast,nmid,nslow size of global 3d matrix
in_ilo,in_ihi input bounds of data I own in fast index
in_jlo,in_jhi input bounds of data I own in mid index
in_klo,in_khi input bounds of data I own in slow index
out_ilo,out_ihi output bounds of data I own in fast index
out_jlo,out_jhi output bounds of data I own in mid index
out_klo,out_khi output bounds of data I own in slow index
scaled 0 = no scaling of result, 1 = scaling
permute permutation in storage order of indices on output
0 = no permutation
1 = permute once = mid->fast, slow->mid, fast->slow
2 = permute twice = slow->fast, fast->mid, mid->slow
nbuf returns size of internal storage buffers used by FFT
------------------------------------------------------------------------- */
struct fft_plan_3d *fft_3d_create_plan_cuda(
MPI_Comm comm, int nfast, int nmid, int nslow,
int in_ilo, int in_ihi, int in_jlo, int in_jhi,
int in_klo, int in_khi,
int out_ilo, int out_ihi, int out_jlo, int out_jhi,
int out_klo, int out_khi,
int scaled, int permute, int *nbuf,bool ainit)
{
#ifdef FFT_CUFFT
struct fft_plan_3d *plan;
int me,nprocs;
int i,num,flag,remapflag,fftflag;
int first_ilo,first_ihi,first_jlo,first_jhi,first_klo,first_khi;
int second_ilo,second_ihi,second_jlo,second_jhi,second_klo,second_khi;
int third_ilo,third_ihi,third_jlo,third_jhi,third_klo,third_khi;
int out_size,first_size,second_size,third_size,copy_size,scratch_size;
int np1,np2,ip1,ip2;
int list[50];
// system specific variables
// query MPI info
MPI_Comm_rank(comm,&me);
MPI_Comm_size(comm,&nprocs);
#ifndef FFT_CUFFT
error->all(FLERR,"ERROR: Trying to use cuda fft without FFT_CUFFT set. Recompile with make option 'cufft=1'.");
#endif
// compute division of procs in 2 dimensions not on-processor
bifactor_cuda(nprocs,&np1,&np2);
ip1 = me % np1;
ip2 = me/np1;
// in case of CUDA FFT every proc does the full FFT in order to avoid data transfers (the problem is other wise heavily bandwidth limited)
int ip1out = ip1;
int ip2out = ip2;
int np1out = np1;
int np2out = np2;
ip1 = 0;
ip2 = 0;
np1 = 1;
np2 = 1;
// allocate memory for plan data struct
plan = (struct fft_plan_3d *) malloc(sizeof(struct fft_plan_3d));
if (plan == NULL) return NULL;
plan->init=ainit;
// remap from initial distribution to layout needed for 1st set of 1d FFTs
// not needed if all procs own entire fast axis initially
// first indices = distribution after 1st set of FFTs
if (in_ilo == 0 && in_ihi == nfast-1)
flag = 0;
else
flag = 1;
if(nprocs>1)flag=1;
MPI_Allreduce(&flag,&remapflag,1,MPI_INT,MPI_MAX,comm);
if (remapflag == 0) {
first_ilo = in_ilo;
first_ihi = in_ihi;
first_jlo = in_jlo;
first_jhi = in_jhi;
first_klo = in_klo;
first_khi = in_khi;
plan->pre_plan = NULL;
}
else {
first_ilo = 0;
first_ihi = nfast - 1;
first_jlo = ip1*nmid/np1;
first_jhi = (ip1+1)*nmid/np1 - 1;
first_klo = ip2*nslow/np2;
first_khi = (ip2+1)*nslow/np2 - 1;
int members=2;
if(plan->init) members=1;
plan->pre_plan =
remap_3d_create_plan(comm,in_ilo,in_ihi,in_jlo,in_jhi,in_klo,in_khi,
first_ilo,first_ihi,first_jlo,first_jhi,
first_klo,first_khi,
members,0,0,2);
if (plan->pre_plan == NULL) return NULL;
}
// 1d FFTs along fast axis
plan->length1 = nfast;
plan->total1 = nfast * nmid * nslow;
// remap from 1st to 2nd FFT
// choose which axis is split over np1 vs np2 to minimize communication
// second indices = distribution after 2nd set of FFTs
second_ilo = ip1*nfast/np1;
second_ihi = (ip1+1)*nfast/np1 - 1;
second_jlo = 0;
second_jhi = nmid - 1;
second_klo = ip2*nslow/np2;
second_khi = (ip2+1)*nslow/np2 - 1;
plan->mid1_plan =
remap_3d_create_plan(comm,
first_ilo,first_ihi,first_jlo,first_jhi,
first_klo,first_khi,
second_ilo,second_ihi,second_jlo,second_jhi,
second_klo,second_khi,
2,1,0,2);
if (plan->mid1_plan == NULL) return NULL;
// 1d FFTs along mid axis
plan->length2 = nmid;
plan->total2 = nfast * nmid * nslow;
// remap from 2nd to 3rd FFT
// if final distribution is permute=2 with all procs owning entire slow axis
// then this remapping goes directly to final distribution
// third indices = distribution after 3rd set of FFTs
flag=1;
MPI_Allreduce(&flag,&remapflag,1,MPI_INT,MPI_MAX,comm);
if (remapflag == 0) {
third_ilo = out_ilo;
third_ihi = out_ihi;
third_jlo = out_jlo;
third_jhi = out_jhi;
third_klo = out_klo;
third_khi = out_khi;
}
else {
third_ilo = ip1*nfast/np1;
third_ihi = (ip1+1)*nfast/np1 - 1;
third_jlo = ip2*nmid/np2;
third_jhi = (ip2+1)*nmid/np2 - 1;
third_klo = 0;
third_khi = nslow - 1;
}
plan->mid2_plan =
remap_3d_create_plan(comm,
second_jlo,second_jhi,second_klo,second_khi,
second_ilo,second_ihi,
third_jlo,third_jhi,third_klo,third_khi,
third_ilo,third_ihi,
2,1,0,2);
if (plan->mid2_plan == NULL) return NULL;
// 1d FFTs along slow axis
plan->length3 = nslow;
plan->total3 = nfast * nmid * nslow;
// remap from 3rd FFT to final distribution
// not needed if permute = 2 and third indices = out indices on all procs
flag=1;
MPI_Allreduce(&flag,&remapflag,1,MPI_INT,MPI_MAX,comm);
if (remapflag == 0)
plan->post_plan = NULL;
else {
plan->post_plan =
remap_3d_create_plan(comm,
third_klo,third_khi,third_ilo,third_ihi,
third_jlo,third_jhi,
out_klo,out_khi,out_ilo,out_ihi,
out_jlo,out_jhi,
2,(permute+1)%3,0,2);
if (plan->post_plan == NULL) return NULL;
}
// configure plan memory pointers and allocate work space
// out_size = amount of memory given to FFT by user
// first/second/third_size = amount of memory needed after pre,mid1,mid2 remaps
// copy_size = amount needed internally for extra copy of data
// scratch_size = amount needed internally for remap scratch space
// for each remap:
// out space used for result if big enough, else require copy buffer
// accumulate largest required remap scratch space
out_size = (out_ihi-out_ilo+1) * (out_jhi-out_jlo+1) * (out_khi-out_klo+1);
first_size = (first_ihi-first_ilo+1) * (first_jhi-first_jlo+1) *
(first_khi-first_klo+1);
second_size = (second_ihi-second_ilo+1) * (second_jhi-second_jlo+1) *
(second_khi-second_klo+1);
third_size = (third_ihi-third_ilo+1) * (third_jhi-third_jlo+1) *
(third_khi-third_klo+1);
plan->ihi_out=out_ihi;
plan->ilo_out=out_ilo;
plan->jhi_out=out_jhi;
plan->jlo_out=out_jlo;
plan->khi_out=out_khi;
plan->klo_out=out_klo;
copy_size = 0;
scratch_size = 0;
if (plan->pre_plan) {
if (first_size <= out_size)
plan->pre_target = 0;
else {
plan->pre_target = 1;
copy_size = MAX(copy_size,first_size);
}
scratch_size = MAX(scratch_size,first_size);
}
if (plan->mid1_plan) {
if (second_size <= out_size)
plan->mid1_target = 0;
else {
plan->mid1_target = 1;
copy_size = MAX(copy_size,second_size);
}
scratch_size = MAX(scratch_size,second_size);
}
if (plan->mid2_plan) {
if (third_size <= out_size)
plan->mid2_target = 0;
else {
plan->mid2_target = 1;
copy_size = MAX(copy_size,third_size);
}
scratch_size = MAX(scratch_size,third_size);
}
if (plan->post_plan)
scratch_size = MAX(scratch_size,out_size);
*nbuf = copy_size + scratch_size;
if (copy_size) {
plan->copy = (FFT_DATA *) malloc(copy_size*sizeof(FFT_DATA));
if (plan->copy == NULL) return NULL;
}
else plan->copy = NULL;
if (scratch_size) {
plan->scratch = (FFT_DATA *) malloc(scratch_size*sizeof(FFT_DATA));
if (plan->scratch == NULL) return NULL;
}
else plan->scratch = NULL;
// system specific pre-computation of 1d FFT coeffs
// and scaling normalization
cufftResult retvalc;
int nfft = (in_ihi-in_ilo+1) * (in_jhi-in_jlo+1) *
(in_khi-in_klo+1);
int nfft_brick = (out_ihi-out_ilo+1) * (out_jhi-out_jlo+1) *
(out_khi-out_klo+1);
int nfft_both = MAX(nfft,nfft_brick);
nfft_both=nfast*nmid*nslow;
plan->cudatasize=nfft_both*sizeof(FFT_DATA);
//retvalc=cufftPlan1d(&(plan->plan_fast), nfast, CUFFT_PLAN,plan->total1/nfast);
//if(retvalc!=CUFFT_SUCCESS) printf("ErrorCUFFT1: %i\n",retvalc);
plan->nfast=nfast;
//retvalc=cufftPlan1d(&(plan->plan_mid), nmid, CUFFT_PLAN,plan->total2/nmid);
//if(retvalc!=CUFFT_SUCCESS) printf("ErrorCUFFT2: %i\n",retvalc);
plan->nmid=nmid;
//retvalc=cufftPlan1d(&(plan->plan_slow), nslow, CUFFT_PLAN,plan->total3/nslow);
//if(retvalc!=CUFFT_SUCCESS) printf("ErrorCUFFT3: %i\n",retvalc);
plan->nslow=nslow;
retvalc=cufftPlan3d(&(plan->plan_3d), nslow,nmid,nfast, CUFFT_PLAN);
if(retvalc!=CUFFT_SUCCESS) printf("ErrorCUFFT3: %i\n",retvalc);
plan->nprocs=nprocs;
plan->me=me;
if (scaled == 0)
plan->scaled = 0;
else {
plan->scaled = 1;
plan->norm = 1.0/(nfast*nmid*nslow);
plan->normnum = (out_ihi-out_ilo+1) * (out_jhi-out_jlo+1) *
(out_khi-out_klo+1);
}
plan->coretime=0;
plan->iterate=0;
plan->ffttime=0;
return plan;
#endif
}
/* ----------------------------------------------------------------------
Destroy a 3d fft plan
------------------------------------------------------------------------- */
void fft_3d_destroy_plan_cuda(struct fft_plan_3d *plan)
{
#ifdef FFT_CUFFT
if (plan->pre_plan) remap_3d_destroy_plan(plan->pre_plan);
if (plan->mid1_plan) remap_3d_destroy_plan(plan->mid1_plan);
if (plan->mid2_plan) remap_3d_destroy_plan(plan->mid2_plan);
if (plan->post_plan) remap_3d_destroy_plan(plan->post_plan);
if (plan->copy) free(plan->copy);
if (plan->scratch) free(plan->scratch);
//cufftDestroy(plan->plan_fast);
//cufftDestroy(plan->plan_mid);
//cufftDestroy(plan->plan_slow);
cufftDestroy(plan->plan_3d);
free(plan);
#endif
}
/* ----------------------------------------------------------------------
recursively divide n into small factors, return them in list
------------------------------------------------------------------------- */
void factor_cuda(int n, int *num, int *list)
{
if (n == 1) {
return;
}
else if (n % 2 == 0) {
*list = 2;
(*num)++;
factor_cuda(n/2,num,list+1);
}
else if (n % 3 == 0) {
*list = 3;
(*num)++;
factor_cuda(n/3,num,list+1);
}
else if (n % 5 == 0) {
*list = 5;
(*num)++;
factor_cuda(n/5,num,list+1);
}
else if (n % 7 == 0) {
*list = 7;
(*num)++;
factor_cuda(n/7,num,list+1);
}
else if (n % 11 == 0) {
*list = 11;
(*num)++;
factor_cuda(n/11,num,list+1);
}
else if (n % 13 == 0) {
*list = 13;
(*num)++;
factor_cuda(n/13,num,list+1);
}
else {
*list = n;
(*num)++;
return;
}
}
/* ----------------------------------------------------------------------
divide n into 2 factors of as equal size as possible
------------------------------------------------------------------------- */
void bifactor_cuda(int n, int *factor1, int *factor2)
{
int n1,n2,facmax;
facmax = static_cast<int> (sqrt((double) n));
for (n1 = facmax; n1 > 0; n1--) {
n2 = n/n1;
if (n1*n2 == n) {
*factor1 = n1;
*factor2 = n2;
return;
}
}
}
/* ----------------------------------------------------------------------
perform just the 1d FFTs needed by a 3d FFT, no data movement
used for timing purposes
Arguments:
in starting address of input data on this proc, all set to 0.0
nsize size of in
flag 1 for forward FFT, -1 for inverse FFT
plan plan returned by previous call to fft_3d_create_plan
------------------------------------------------------------------------- */
void fft_1d_only_cuda(FFT_DATA *data, int nsize, int flag, struct fft_plan_3d *plan)
{
#ifdef FFT_CUFFT
int i,total,length,offset,num;
double norm;
// system specific constants
// total = size of data needed in each dim
// length = length of 1d FFT in each dim
// total/length = # of 1d FFTs in each dim
// if total > nsize, limit # of 1d FFTs to available size of data
int total1 = plan->total1;
int length1 = plan->length1;
int total2 = plan->total2;
int length2 = plan->length2;
int total3 = plan->total3;
int length3 = plan->length3;
if (total1 > nsize) total1 = (nsize/length1) * length1;
if (total2 > nsize) total2 = (nsize/length2) * length2;
if (total3 > nsize) total3 = (nsize/length3) * length3;
// perform 1d FFTs in each of 3 dimensions
// data is just an array of 0.0
cudaMemcpy((void**) &(plan->cudata), (void*) data, plan->cudatasize,cudaMemcpyHostToDevice);
if (flag == -1) {
cufft(plan->plan_3d, plan->cudata, plan->cudata,CUFFT_FORWARD);
/*cufft(plan->plan_fast, plan->cudata, plan->cudata,CUFFT_FORWARD);
cufft(plan->plan_mid, plan->cudata, plan->cudata,CUFFT_FORWARD);
cufft(plan->plan_slow, plan->cudata, plan->cudata,CUFFT_FORWARD);*/
} else {
cufft(plan->plan_3d, plan->cudata, plan->cudata,CUFFT_FORWARD);
/*cufft(plan->plan_fast, plan->cudata, plan->cudata,CUFFT_INVERSE);
cufft(plan->plan_mid,plan->cudata, plan->cudata,CUFFT_INVERSE);
cufft(plan->plan_slow, plan->cudata, plan->cudata,CUFFT_INVERSE);*/
}
cudaMemcpy((void*) data, (void**) &(plan->cudata), plan->cudatasize,cudaMemcpyDeviceToHost);
// scaling if required
// limit num to size of data
#endif
}

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