irpjast/qmckl_dgemm.org

QMCkl dgemm

• Fortran interface
• C code

Generated from qmckl_dgemm.org

/* <<header>> */

#include <cblas.h>
#include <stdint.h>
#include <assert.h>
#include <stdlib.h>

<<tasks_init>>

<<dgemm_args>>

<<dgemm_rec>>

<<dgemm>>

<<tasks_run>>

Fortran interface

! <<header>>

module qmckl_blas
  use :: iso_c_binding

  interface
     subroutine qmckl_dgemm(transa, transb, m, n, k, &
          alpha, A, lda, B, ldb, beta, C, ldc, res) bind(C)
       use :: iso_c_binding
       implicit none
       character(kind=c_char  ), value :: transa, transb
       integer  (kind=c_int   ), value :: m, n, k, lda, ldb, ldc
       real     (kind=c_double), value :: alpha, beta
       real     (kind=c_double)        :: A(lda,*), B(ldb,*), C(ldc,*)
       integer  (kind=c_int64_t)       :: res
     end subroutine qmckl_dgemm
  end interface

  interface
     subroutine qmckl_tasks_run(gemms, ngemms) bind(C)
       use :: iso_c_binding
       implicit none
       integer (kind=c_int32_t), value :: ngemms
       integer (kind=c_int64_t)        :: gemms(ngemms)
     end subroutine qmckl_tasks_run
  end interface

end module qmckl_blas

TODO C code

The main function packs the arguments in the struct and returns the struct as a result.

struct dgemm_args {
double alpha;
double beta;
double* A;
double* B;
double* C;
int m;
int n;
int k;
int lda;
int ldb;
int ldc;
CBLAS_LAYOUT transa;
CBLAS_LAYOUT transb;
};

void qmckl_dgemm(char transa, char transb,
              int m, int n, int k,
              double alpha,
              double* A, int lda,
              double* B, int ldb,
              double beta,
              double* C, int ldc,
              int64_t* result)
{
struct dgemm_args* args = (struct dgemm_args*) malloc (sizeof(struct dgemm_args));
assert (args != NULL);
*result = (int64_t) args;

args->alpha = alpha;
args->beta  = beta ;
args->A = A;
args->B = B;
args->C = C;
args->m = m;
args->n = n;
args->k = k;
args->lda = lda;
args->ldb = ldb;
args->ldc = ldc;

if (transa == 'T' || transa == 't') {
 args->transa = CblasTrans;
} else {
 args->transa = CblasNoTrans;
}

if (transa == 'T' || transa == 't') {
 args->transb = CblasTrans;
} else {
 args->transb = CblasNoTrans;
}

}

To run the dgemms as tasks, pass all the dgemms to do to the following function. It call task-based the recursive dgemm defined below.

void qmckl_tasks_run(struct dgemm_args** gemms, int ngemms)
{
#pragma omp parallel
{
 #pragma omp single
 {
   for (int i=0 ; i<ngemms ; ++i)
   {
     qmckl_dgemm_rec(*(gemms[i]));
   }
 }
 #pragma omp taskwait
}
}

#define MIN_SIZE 512
#include<stdio.h>

static void qmckl_dgemm_rec(struct dgemm_args args) {

//  printf("%5d %5d\n", args.m, args.n);

if ( (args.m <= MIN_SIZE) || (args.n <= MIN_SIZE)) {
 #pragma omp task
 {
   printf("BLAS %5d %5d %5d\n", args.m, args.n, args.k);
   cblas_dgemm(CblasColMajor, args.transa, args.transb,
               args.m, args.n, args.k, args.alpha,
               args.A, args.lda, args.B, args.ldb,
               args.beta, args.C, args.ldc);
 }
} else {

 int m1 = args.m / 2;
 int m2 = args.m - m1;
 int n1 = args.n / 2;
 int n2 = args.n - n1;
   
 #pragma omp task
 {
   struct dgemm_args args_1 = args;
   args_1.m = m1;
   args_1.n = n1;
   qmckl_dgemm_rec(args_1);
 }
 
 #pragma omp task
 {
   // TODO: assuming 'N', 'N' here
   struct dgemm_args args_2 = args;
   args_2.B = args.B + args.ldb*n1;
   args_2.C = args.C + args.ldc*n1;
   args_2.m = m1;
   args_2.n = n2;
   qmckl_dgemm_rec(args_2);
 }
 
 #pragma omp task
 {
   struct dgemm_args args_3 = args;
   args_3.A = args.A + m1;
   args_3.C = args.C + m1;
   args_3.m = m2;
   args_3.n = n1;
   qmckl_dgemm_rec(args_3);
 }
 
 #pragma omp task
 {
   struct dgemm_args args_4 = args;
   args_4.A = args.A + m1;
   args_4.B = args.B + args.ldb*n1;
   args_4.C = args.C + m1 + args.ldc*n1;
   args_4.m = m2;
   args_4.n = n2;
   qmckl_dgemm_rec(args_4);
 }
}

}