Hello,I write a simple program to print time every 1ms.
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <sys/resource.h>
#include <sys/time.h>
int main(void)
{
pid_t pid = getpid();
setpriority(PRIO_PROCESS, pid, -20);
while (1)
{
usleep(1000);
struct timeval t;
gettimeofday(&t, NULL);
printf("%u.%06u\n", t.tv_sec, t.tv_usec);
}
return 0;
}
while I get the following result.
......
1402463778.370107
1402463778.371202
1402463778.372297
1402463778.373393
1402463778.374487
1402463778.375582
1402463778.376677
1402463778.377772
1402463778.378893
1402463778.380010
1402463778.381105
1402463778.382199
1402463778.383293
1402463778.384388 ***********
1402463778.718214 ***********lost
1402463778.719311
1402463778.720407
1402463778.721502
1402463778.722597
1402463778.723691
1402463778.724786
1402463778.725896
1402463778.726992
......
about 300ms lost every 1s.Why?
Then I use setitimer() and pause()
struct itimerval tv;
tv.it_interval.tv_sec = 0;
tv.it_interval.tv_usec = 1000;
tv.it_value.tv_sec = 0;
tv.it_value.tv_usec = 1000;
I get the following result.
1402465124.8487241402465124.851723
1402465124.852722
1402465124.854723
1402465124.855724
1402465124.856722
1402465124.858724
1402465124.860722
1402465124.862724
1402465124.863722
1402465124.865724
1402465124.866724
1402465124.869723
1402465124.870721 ******
1402465124.872723 ******lost
1402465124.873724
1402465124.874722
1402465124.8767231402465124.879724 ******output overlap
1402465124.880723
1402465124.881721
1402465124.883724
1402465124.884741
1402465124.885722
1402465124.888721
1402465124.890723
1402465124.891724
1402465124.892722
1402465124.8947241402465124.897723
lost and output overlap.Why?
Thanks in advance for any help.
