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#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/time.h>
#include <stdlib.h>
#include <unistd.h>
typedef unsigned long long uint64;
struct timeval t1;
void start(struct timeval *tv)
{
gettimeofday (tv, NULL);
}
uint64 time_delta(struct timeval *start, struct timeval *stop)
{
uint64 secs, usecs;
secs = stop->tv_sec - start->tv_sec;
usecs = stop->tv_usec - start->tv_usec;
if (usecs < 0) {
secs--;
usecs += 1000000;
}
return secs * 1000000 + usecs;
}
uint64 stop(struct timeval *begin)
{
struct timeval end;
gettimeofday (&end, NULL);
return time_delta (begin, &end);
}
int main()
{
int fd, i;
char buf[1024];
uint64 nsecs;
system ("touch foo");
fd = open ("foo", O_RDWR);
start(&t1);
for (i = 0; i < 1000000; i++) {
if (read (fd, buf, 0) < 0)
perror("read");
}
nsecs = stop(&t1) / 1000;
printf("%lld ", nsecs);
start(&t1);
for (i = 0; i < 1000000; i++) {
if (write (fd, buf, 0) < 0)
perror("write");
}
nsecs = stop(&t1) / 1000;
close (fd);
printf("%lld\n", nsecs);
return 0;
}
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