C<setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )>
-Start up an interval timer: after a certain time, a signal is arrives,
-and more may keep arriving at certain intervals. To disable a timer,
-use time of zero. If interval is set to zero (or unspecified), the
-timer is disabled after the next delivered signal.
+Start up an interval timer: after a certain time, a signal arrives,
+and more signals may keep arriving at certain intervals. To disable
+a timer, use time of zero. If interval is set to zero (or unspecified),
+the timer is disabled B<after> the next delivered signal.
Use of interval timers may interfere with alarm(), sleep(), and usleep().
In standard-speak the "interaction is unspecified", which means that
the timer expires.
ITIMER_VIRTUAL counts time in (process) I<virtual time>, that is, only
-when the process is running. In multiprocessing/user/CPU systems this
-may be much less than real time. (This time is also known as the
-I<user time>.) SIGVTALRM is delivered when the timer expires.
+when the process is running. In multiprocessor/user/CPU systems this
+may be more or less than real or wallclock time. (This time is also
+known as the I<user time>.) SIGVTALRM is delivered when the timer expires.
ITIMER_PROF counts time when either the process virtual time or when
the operating system is running on behalf of the process (such as