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/*************************************************************
a simple code for measuring the elapsed time for I/O
by Taisuke Ozaki (AIST-RICS), 28. Dec. 2005
compiling:
e.g.
gcc -O3 io_tester.c -lm -o io_tester
usage:
./io_tester
Then, we will find the elapsed time for writing data to
the disk space in your display like this:
elapased time for I/O 5.83752 (s)
*************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <math.h>
#include <time.h>
#include <sys/types.h>
#include <sys/times.h>
#include <sys/time.h>
#define Msize1 100
#define Msize2 200
#define Msize3 300
#define bsize 1048576
struct timeval2 {
long tv_sec; /* second */
long tv_usec; /* microsecond */
};
double rnd(double width);
void dtime(double *t);
int main(int argc, char *argv[])
{
int i,j,k;
double ***V;
double stime,etime;
FILE *fp;
char fname[300];
char buf[bsize]; /* setvbuf */
/* allocate array */
V = (double***)malloc(sizeof(double**)*Msize1);
for (i=0; i<Msize1; i++){
V[i] = (double**)malloc(sizeof(double*)*Msize2);
for (j=0; j<Msize2; j++){
V[i][j] = (double*)malloc(sizeof(double)*Msize3);
}
}
/* set data */
for (i=0; i<Msize1; i++){
for (j=0; j<Msize2; j++){
for (k=0; k<Msize3; k++){
V[i][j][k] = rnd(1.0);
}
}
}
/* write data */
dtime(&stime);
sprintf(fname,"IO_test.txt");
if ((fp = fopen(fname,"w")) != NULL){
setvbuf(fp,buf,_IOFBF,bsize); /* setvbuf */
for (i=0; i<Msize1; i++){
for (j=0; j<Msize2; j++){
for (k=0; k<Msize3; k++){
fprintf(fp,"%13.3E",V[i][j][k]);
if ((k+1)%6==0) fprintf(fp,"\n");
}
/* avoid double \n\n when Msize3%6 == 0 */
if (Msize3%6!=0) fprintf(fp,"\n");
}
}
fclose(fp);
}
else {
printf("could not open a file\n");
}
dtime(&etime);
printf(" elapased time for I/O %10.5f (s)\n",etime-stime);
/* free array */
for (i=0; i<Msize1; i++){
for (j=0; j<Msize2; j++){
free(V[i][j]);
}
free(V[i]);
}
free(V);
/* return */
return 0;
}
double rnd(double width)
{
double result;
result = rand();
while (width<result){
result = result/2.0;
}
result = result - width*0.75;
return result;
}
void dtime(double *t)
{
/* real time */
struct timeval timev;
gettimeofday(&timev, NULL);
*t = timev.tv_sec + (double)timev.tv_usec*1e-6;
}
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