4.3BSD - /usr/man/cat3/usleep.0

USLEEP(3)                                                            USLEEP(3)


NAME
       usleep - suspend execution for interval

SYNOPSIS
       usleep(useconds)
       unsigned useconds;

DESCRIPTION
       The  current  process  is  suspended  from  execution for the number of
       microseconds specified by the argument.  The actual suspension time may
       be  an  arbitrary amount longer because of other activity in the system
       or because of the time spent in processing the call.

       The routine is implemented by setting an  interval  timer  and  pausing
       until  it  occurs.   The  previous  state  of  this  timer is saved and
       restored.  If the sleep time exceeds the time to the expiration of  the
       previous  timer,  the  process  sleeps only until the signal would have
       occurred, and the signal is sent a short time later.

       This routine is implemented using setitimer(2); it requires eight  sys‐
       tem calls each time it is invoked.  A similar but less compatible func‐
       tion can be obtained with a single  select(2);  it  would  not  restart
       after signals, but would not interfere with other uses of setitimer.

SEE ALSO
       setitimer(2), getitimer(2), sigpause(2), ualarm(3), sleep(3), alarm(3)


4.3 Berkeley Distribution        May 15, 1986                        USLEEP(3)