Here's the test program I used to verify that the VDSO gettimeofday
and clock_gettime are giving correct results.
Paul.
/*
* Copyright 2010 Paul Mackerras <pau...@samba.org>, IBM.
*
* This program is free software; it may be used and redistributed
* under the terms of the GNU Public Licence, either version 2, or
* (at your option) any later version.
*/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
#include <sys/unistd.h>
#include <linux/auxvec.h>
#include <asm/unistd.h>
#define TVTIME(tv) ((tv).tv_sec * 1000000000ull + (tv).tv_usec * 1000ull)
#define TSTIME(ts) ((ts).tv_sec * 1000000000ull + (ts).tv_nsec)
main(int ac, char **av)
{
struct timeval tv1, tv2;
struct timespec ts1, ts2, s1, s2;
int count;
for (count = 0; count < 10000000; ++count) {
gettimeofday(&tv1, NULL);
clock_gettime(CLOCK_REALTIME, &ts1);
syscall(__NR_clock_gettime, CLOCK_REALTIME, &s1);
gettimeofday(&tv2, NULL);
clock_gettime(CLOCK_REALTIME, &ts2);
syscall(__NR_clock_gettime, CLOCK_REALTIME, &s2);
if (TVTIME(tv1) > TSTIME(ts1) ||
TSTIME(ts1) > TSTIME(s1) ||
TSTIME(s1) - s1.tv_nsec % 1000 > TVTIME(tv2) ||
TVTIME(tv2) > TSTIME(ts2) ||
TSTIME(ts2) > TSTIME(s2)) {
printf("ERROR: %lld %lld %lld\n\t%lld %lld %lld\n",
TVTIME(tv1), TSTIME(ts1), TSTIME(s1),
TVTIME(tv2), TSTIME(ts2), TSTIME(s2));
exit(1);
}
}
exit(0);
}
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