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#include <u.h>
#include <libc.h>
typedef uvlong u64int;
#define TWID64 ((u64int)~(u64int)0)
u64int
unittoull(char *s)
{
char *es;
u64int n;
if(s == nil)
return TWID64;
n = strtoul(s, &es, 0);
if(*es == 'k' || *es == 'K'){
n *= 1024;
es++;
}else if(*es == 'm' || *es == 'M'){
n *= 1024*1024;
es++;
}else if(*es == 'g' || *es == 'G'){
n *= 1024*1024*1024;
es++;
}
if(*es != '\0')
return TWID64;
return n;
}
void
main(int argc, char *argv[])
{
int fd, i;
int n = 1000, m;
int s = 1;
double *t, t0, t1;
uchar *buf;
double a, d, max, min;
m = OREAD;
ARGBEGIN{
case 'n':
n = atoi(ARGF());
break;
case 's':
s = unittoull(ARGF());
if(s < 1 || s > 1024*1024)
sysfatal("bad size");
break;
case 'r':
m = OREAD;
break;
case 'w':
m = OWRITE;
break;
}ARGEND
fd = 0;
if(argc == 1){
fd = open(argv[0], m);
if(fd < 0)
sysfatal("could not open file: %s: %r", argv[0]);
}
buf = malloc(s);
t = malloc(n*sizeof(double));
t0 = nsec();
for(i=0; i<n; i++){
if(m == OREAD){
if(pread(fd, buf, s, 0) < s)
sysfatal("bad read: %r");
}else{
if(pwrite(fd, buf, s, 0) < s)
sysfatal("bad write: %r");
}
t1 = nsec();
t[i] = (t1 - t0)*1e-3;
t0 = t1;
}
a = 0.;
d = 0.;
max = 0.;
min = 1e12;
for(i=0; i<n; i++){
a += t[i];
if(max < t[i])
max = t[i];
if(min > t[i])
min = t[i];
}
a /= n;
for(i=0; i<n; i++)
d += (a - t[i]) * (a - t[i]);
d /= n;
d = sqrt(d);
print("avg = %.0fµs min = %.0fµs max = %.0fµs dev = %.0fµs\n", a, min, max, d);
exits(0);
}
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