#include <stdio.h>
#include <sys/times.h>
#include <sys/types.h>
#include <time.h>
#define CACHE_MIN (1024) /* smallest cache */
#define CACHE_MAX (1024*1024) /* largest cache */
#define SAMPLE 10 /* to get a larger time sample */
#define CLK_TCK 60 /* number clock ticks per second */
int x[CACHE_MAX]; /* array going to stride through */
 
double get_seconds() { /* routine to read time */
	struct tms rusage;
	times(&rusage); /* UNIX utility: time in clock ticks */
	return (double) (rusage.tms_utime)/CLK_TCK;
}
void main() {
int register i, index, stride, limit, temp;
int steps, tsteps, csize;
double sec0, sec; /* timing variables */
 
for (csize=CACHE_MIN; csize <= CACHE_MAX; csize=csize*2) 
	for (stride=1; stride <= csize/2; stride=stride*2) {
		sec = 0; /* initialize timer */
		limit = csize-stride+1; /* cache size this loop */
 
		steps = 0;
		do { /* repeat until collect 1 second */
		sec0 = get_seconds(); /* start timer */
		for (i=SAMPLE*stride;i!=0;i=i-1) /* larger sample */
		  for (index=0; index < limit; index=index+stride) 
				x[index] = x[index] + 1; /* cache
access */
		steps = steps + 1; /* count while loop iterations */
		sec = sec + (get_seconds() - sec0);/* end timer */
		} while (sec < 1.0); /* until collect 1 second */
 
		/* Repeat empty loop to loop subtract overhead */
		tsteps = 0; /* used to match no. while iterations */
		do { /* repeat until same no. iterations as above */
		sec0 = get_seconds(); /* start timer */
		for (i=SAMPLE*stride;i!=0;i=i-1) /* larger sample */
		  for (index=0; index < limit; index=index+stride) 
				temp = temp + index; /* dummy code */
		tsteps = tsteps + 1; /* count while iterations */
		sec = sec - (get_seconds() - sec0);/* - overhead */
		} while (tsteps<steps); /* until = no. iterations */
 
		printf("Size:%7d Stride:%7d read+write:%l4.0f ns\n",
			csize*sizeof(int), stride*sizeof(int),
(double) 
		sec*1e9/(steps*SAMPLE*stride*((limit-1)/stride+1)));
	}; /* end of both outer for loops */
}