Copyright © tutorialspoint.com
int nanosleep(const struct timespec *req, struct timespec *rem);
DESCRIPTION
nanosleep() delays the execution of the program for at least the time specified in
*req. The function can return earlier if a signal has been delivered to the
process. In this case, it returns -1, sets errno to
EINTR, and writes the
remaining time into the structure pointed to by
rem unless
rem is NULL.
The value of
*rem can then be used to call
nanosleep() again and complete the specified pause.
The structure timespec is used to specify intervals of time with nanosecond precision. It is specified in <time.h> and has the form
struct timespec { time_t tv_sec; /* seconds */ long tv_nsec; /* nanoseconds */ }; |
The value of the nanoseconds field must be in the range 0 to 999999999.
Compared to sleep(3) and usleep(3), nanosleep() has the advantage of not affecting any signals, it is standardized by POSIX, it provides higher timing resolution, and it allows to continue a sleep that has been interrupted by a signal more easily.
Tag | Description |
---|---|
EFAULT | Problem with copying information from user space. |
EINTR | The pause has been interrupted by a non-blocked signal that was delivered to the process. The remaining sleep time has been written into *rem so that the process can easily call nanosleep() again and continue with the pause. |
EINVAL | The value in the tv_nsec field was not in the range 0 to 999999999 or tv_sec was negative. |
In Linux 2.4, if nanosleep() is stopped by a signal (e.g., SIGTSTP), then the call fails with the error EINTR after the process is resumed by a SIGCONT signal. If the system call is subsequently restarted, then the time that the process spent in the stopped state is not counted against the sleep interval.
Copyright © tutorialspoint.com