Re: [Starpu-devel] Performance issues when specifying const and __attribute__ ((output))

[Mehdi AMINI <mehdi.amini@silkan.com>]

Hi all,

Le 02/07/2012 19:51, Samuel Thibault a écrit :
> Mehdi AMINI, le Mon 02 Jul 2012 14:26:05 +0200, a écrit :
> > Le 02/07/2012 13:52, Samuel Thibault a écrit :
> > > Mehdi AMINI, le Mon 02 Jul 2012 12:10:19 +0200, a écrit :
> > > > $ STARPU_NCUDA=1 STARPU_NCPUS=0 ./bicg_starpu_naive
> > > > 192.2
> > > > $ STARPU_NCUDA=1 STARPU_NCPUS=0 ./bicg_starpu
> > > > 746.5
> > >
> > > Ouch!
> > >
> > > Could you dump traces so we have an idea of what is happening?
> >
> > Are the FXT traces enough? You'll find them here for both versions :
> >
> > http://mehdi.amini.fr/StarPU/
>
> So it seems it spends almost all its time in PushingOutput, which is not
> supposed to happen. Could you perhaps run in gdb, interrupt it during
> the run, and use
>
> thread apply all bt
>
> to have an idea at where it most often is? Or alternatively, compile
> with gprof, but that might be more involved.
>
> Would it be possible to see your code?  It is hard to have an idea
> without being able to run it.


The code is enclosed, it runs 10 times each version.

$ STARPU_NOPENCL=0 STARPU_NCUDA=1 STARPU_NCPUS=0 ./bicg_starpu
Run naive...
223.6
Run 'optimized'...
749.1
Run naive...
222.1
Run 'optimized'...
739.8
Run naive...
223.0
Run 'optimized'...
...



Mehdi





/*
 * file for bicg.c
 */
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <math.h>



/* Timer code (gettimeofday). */
static double t_start, t_end;

double timer_get_time()
{
    struct timeval t;
    if (gettimeofday (&t, NULL) != 0) {
      perror("Error gettimeofday !\n");
      exit(1);
    }
    return (t.tv_sec + t.tv_usec * 1.0e-6);
}


void timer_start() {
  t_start = timer_get_time();
}

void timer_stop() {
  t_end = timer_get_time();
}

void timer_display() {
  printf ("%0.1lf\n", (t_end - t_start)*1000);
}

void timer_stop_display() {
  timer_stop();
  timer_display();
}


void p4a_launcher_main(__attribute__((output)) double s[8000], int ny) __attribute__((task));
void p4a_launcher_main_accel(__attribute__((output)) double s[8000], int ny) __attribute__ ((task_implementation ("cuda", p4a_launcher_main)));
void p4a_launcher_main(__attribute__((output)) double s[8000], int ny) { fprintf(stderr,"CPU stub\n"); /*exit(1);*/ } 

void p4a_launcher_main_1(const double *A, const double p[8000], __attribute__((output)) double q[8000], int nx, int ny) __attribute__((task));
void p4a_launcher_main_1_accel(const double *A, const double p[8000], __attribute__((output)) double q[8000], int nx, int ny) __attribute__ ((task_implementation ("cuda", p4a_launcher_main_1)));
void p4a_launcher_main_1(const double *A, const double p[8000], __attribute__((output)) double q[8000], int nx, int ny) { fprintf(stderr,"CPU stub\n"); /*exit(1);*/ } 

void p4a_launcher_main_2(const double *A, double s[8000], int i, int ny, double r_0) __attribute__((task));
void p4a_launcher_main_2_accel(const double *A, double s[8000], int i, int ny, double r_0) __attribute__ ((task_implementation ("cuda", p4a_launcher_main_2)));
void p4a_launcher_main_2(const double *A, double s[8000], int i, int ny, double r_0) { fprintf(stderr,"CPU stub\n"); /*exit(1);*/ } 


void naive_p4a_launcher_main(double s[8000], int ny) __attribute__((task));
void naive_p4a_launcher_main_accel(double s[8000], int ny) __attribute__ ((task_implementation ("cuda", naive_p4a_launcher_main)));
void naive_p4a_launcher_main(double s[8000], int ny) { fprintf(stderr,"CPU stub\n"); /*exit(1);*/ } 

void naive_p4a_launcher_main_1(double *A, double p[8000], double q[8000], int nx, int ny) __attribute__((task));
void naive_p4a_launcher_main_1_accel(double *A, double p[8000], double q[8000], int nx, int ny) __attribute__ ((task_implementation ("cuda", naive_p4a_launcher_main_1)));
void naive_p4a_launcher_main_1(double *A, double p[8000], double q[8000], int nx, int ny) { fprintf(stderr,"CPU stub\n"); /*exit(1);*/ } 

void naive_p4a_launcher_main_2(double *A, double s[8000], int i, int ny, double r_0) __attribute__((task));
void naive_p4a_launcher_main_2_accel(double *A, double s[8000], int i, int ny, double r_0) __attribute__ ((task_implementation ("cuda", naive_p4a_launcher_main_2)));
void naive_p4a_launcher_main_2(double *A, double s[8000], int i, int ny, double r_0) { fprintf(stderr,"CPU stub\n"); /*exit(1);*/ } 




static void init_array(double A[8000][8000],double r[8000],double p[8000])
{
   int i, j;
   for(i = 0; i <= 7999; i += 1) {
      r[i] = i*3.14159265358979323846;
      p[i] = i*3.14159265358979323846;
      for(j = 0; j <= 7999; j += 1)
         A[i][j] = (double) i*j/8000;
   }
}
int main(int argc, char **argv)
{
   int i;
   int nx = 8000;
   int ny = 8000;

#pragma starpu initialize

   double A[8000][8000];
   double r[8000];
   double s[8000];
   double p[8000];
   double q[8000];

#pragma starpu register A
#pragma starpu register r
#pragma starpu register s
#pragma starpu register p
#pragma starpu register q

   int nruns;
   for(nruns=0;nruns<10;nruns++) {

     printf("Run naive...\n");
     
     /* Initialize array. */
#pragma starpu acquire A
#pragma starpu acquire r
#pragma starpu acquire q
     init_array(A,r,p);
#pragma starpu release A
#pragma starpu release r
#pragma starpu release q
 
     /* Start timer. */
     timer_start();
     naive_p4a_launcher_main(s, ny);
     naive_p4a_launcher_main_1((double *)A, p, q, nx, ny);
     for(i = 0; i <= nx-1; i += 1) {
      double r_0 = r[i];
      naive_p4a_launcher_main_2((double *)A, s, i, ny, r_0);
     }
     /* Stop and print timer. */
#pragma starpu acquire s
#pragma starpu acquire q
     timer_stop_display();
#pragma starpu release s
#pragma starpu release q


     printf("Run 'optimized'...\n");

     /* Initialize array. */
#pragma starpu acquire A
#pragma starpu acquire r
#pragma starpu acquire q
     init_array(A,r,p);
#pragma starpu release A
#pragma starpu release r
#pragma starpu release q


     /* Start timer. */
     timer_start();
     p4a_launcher_main(s, ny);
     p4a_launcher_main_1((double *)A, p, q, nx, ny);
     for(i = 0; i <= nx-1; i += 1) {
      double r_0 = r[i];
      p4a_launcher_main_2((double *)A, s, i, ny, r_0);
     }
     /* Stop and print timer. */
#pragma starpu acquire s
#pragma starpu acquire q
     timer_stop_display();
#pragma starpu release s
#pragma starpu release q
   }
   
#pragma starpu unregister s
#pragma starpu unregister q
#pragma starpu unregister A
#pragma starpu unregister r
#pragma starpu unregister p 
#pragma starpu shutdown
   return 0;

}

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Description: application/shellscript

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Description: application/cu-seeme