-/* kern_time.c 5.6 82/09/08 */
+/* kern_time.c 5.7 82/09/11 */
#include "../h/param.h"
#include "../h/dir.h" /* XXX */
/*
* Time of day and interval timer support.
+ *
+ * These routines provide the kernel entry points to get and set
+ * the time-of-day and per-process interval timers. Subroutines
+ * here provide support for adding and subtracting timeval structures
+ * and decrementing interval timers, optionally reloading the interval
+ * timers when they expire.
*/
gettimeofday()
if (!suser())
return;
+/* WHAT DO WE DO ABOUT PENDING REAL-TIME TIMEOUTS??? */
boottime.tv_sec += tv->tv_sec - time.tv_sec;
s = spl7(); time = *tv; splx(s);
clockset();
}
-timevaladd(t1, t2)
- struct timeval *t1, *t2;
-{
-
- t1->tv_sec += t2->tv_sec;
- t1->tv_usec += t2->tv_usec;
- timevalfix(t1);
-}
-
-timevalsub(t1, t2)
- struct timeval *t1, *t2;
-{
-
- t1->tv_sec -= t2->tv_sec;
- t1->tv_usec -= t2->tv_usec;
- timevalfix(t1);
-}
-
-timevalfix(t1)
- struct timeval *t1;
-{
-
- if (t1->tv_usec < 0) {
- t1->tv_sec--;
- t1->tv_usec += 1000000;
- }
- if (t1->tv_usec >= 1000000) {
- t1->tv_sec++;
- t1->tv_usec -= 1000000;
- }
-}
-
+/*
+ * Get value of an interval timer. The process virtual and
+ * profiling virtual time timers are kept in the u. area, since
+ * they can be swapped out. These are kept internally in the
+ * way they are specified externally: in time until they expire.
+ *
+ * The real time interval timer is kept in the process table slot
+ * for the process, and its value (it_value) is kept as an
+ * absolute time rather than as a delta, so that it is easy to keep
+ * periodic real-time signals from drifting.
+ *
+ * Virtual time timers are processed in the hardclock() routine of
+ * kern_clock.c. The real time timer is processed by a timeout
+ * routine, called from the softclock() routine. Since a callout
+ * may be delayed in real time due to interrupt processing in the system,
+ * it is possible for the real time timeout routine (realitexpire, given below),
+ * to be delayed in real time past when it is supposed to occur. It
+ * does not suffice, therefore, to reload the real timer .it_value from the
+ * real time timers .it_interval. Rather, we compute the next time in
+ * absolute time the timer should go off.
+ */
getitimer()
{
register struct a {
}
s = spl7();
if (uap->which == ITIMER_REAL) {
+ /*
+ * Convert from absoulte to relative time in .it_value
+ * part of real time timer. If time for real time timer
+ * has passed return 0, else return difference between
+ * current time and time for the timer to go off.
+ */
aitv = u.u_procp->p_realtimer;
if (timerisset(&aitv.it_value))
if (timercmp(&aitv.it_value, &time, <))
}
s = spl7();
if (uap->which == ITIMER_REAL) {
- untimeout(unrto, p);
+ untimeout(realitexpire, p);
if (timerisset(&aitv.it_value)) {
timevaladd(&aitv.it_value, &time);
- timeout(unrto, p, hzto(&aitv.it_value));
+ timeout(realitexpire, p, hzto(&aitv.it_value));
}
p->p_realtimer = aitv;
} else
splx(s);
}
-unrto(p)
+/*
+ * Real interval timer expired:
+ * send process whose timer expired an alarm signal.
+ * If time is not set up to reload, then just return.
+ * Else compute next time timer should go off which is > current time.
+ * This is where delay in processing this timeout causes multiple
+ * SIGALRM calls to be compressed into one.
+ */
+realitexpire(p)
register struct proc *p;
{
int s;
timevaladd(&p->p_realtimer.it_value,
&p->p_realtimer.it_interval);
if (timercmp(&p->p_realtimer.it_value, &time, >)) {
- timeout(unrto, p, hzto(&p->p_realtimer.it_value));
+ timeout(realitexpire,
+ p, hzto(&p->p_realtimer.it_value));
splx(s);
return;
}
}
}
+/*
+ * Check that a proposed value to load into the .it_value or
+ * .it_interval part of an interval timer is acceptable, and
+ * fix it to have at least minimal value (i.e. if it is less
+ * than the resolution of the clock, round it up.)
+ */
itimerfix(tv)
struct timeval *tv;
{
return (0);
}
+/*
+ * Decrement an interval timer by a specified number
+ * of microseconds, which must be less than a second,
+ * i.e. < 1000000. If the timer expires, then reload
+ * it. In this case, carry over (usec - old value) to
+ * reducint the value reloaded into the timer so that
+ * the timer does not drift. This routine assumes
+ * that it is called in a context where the timers
+ * on which it is operating cannot change in value.
+ */
itimerdecr(itp, usec)
register struct itimerval *itp;
int usec;
if (itp->it_value.tv_usec < usec) {
if (itp->it_value.tv_sec == 0) {
+ /* expired, and already in next interval */
usec -= itp->it_value.tv_usec;
goto expire;
}
usec = 0;
if (timerisset(&itp->it_value))
return (1);
+ /* expired, exactly at end of interval */
expire:
if (timerisset(&itp->it_interval)) {
itp->it_value = itp->it_interval;
itp->it_value.tv_sec--;
}
} else
- itp->it_value.tv_usec = 0;
+ itp->it_value.tv_usec = 0; /* sec is already 0 */
return (0);
}
+/*
+ * Add and subtract routines for timevals.
+ * N.B.: subtract routine doesn't deal with
+ * results which are before the beginning,
+ * it just gets very confused in this case.
+ * Caveat emptor.
+ */
+timevaladd(t1, t2)
+ struct timeval *t1, *t2;
+{
+
+ t1->tv_sec += t2->tv_sec;
+ t1->tv_usec += t2->tv_usec;
+ timevalfix(t1);
+}
+
+timevalsub(t1, t2)
+ struct timeval *t1, *t2;
+{
+
+ t1->tv_sec -= t2->tv_sec;
+ t1->tv_usec -= t2->tv_usec;
+ timevalfix(t1);
+}
+
+timevalfix(t1)
+ struct timeval *t1;
+{
+
+ if (t1->tv_usec < 0) {
+ t1->tv_sec--;
+ t1->tv_usec += 1000000;
+ }
+ if (t1->tv_usec >= 1000000) {
+ t1->tv_sec++;
+ t1->tv_usec -= 1000000;
+ }
+}
+
#ifndef NOCOMPAT
otime()
{
setthetime(&tv);
}
-#include "../h/timeb.h"
+/* from old timeb.h */
+struct timeb {
+ time_t time;
+ u_short millitm;
+ short timezone;
+ short dstflag;
+};
oftime()
{
register struct a {
struct timeb *tp;
} *uap;
- struct timeb t;
+ struct timeb tb;
uap = (struct a *)u.u_ap;
(void) spl7();
- t.time = time.tv_sec;
- t.millitm = time.tv_usec / 1000;
+ tb.time = time.tv_sec;
+ tb.millitm = time.tv_usec / 1000;
(void) spl0();
- t.timezone = tz.tz_minuteswest;
- t.dstflag = tz.tz_dsttime;
- if (copyout((caddr_t)&t, (caddr_t)uap->tp, sizeof(t)) < 0)
+ tb.timezone = tz.tz_minuteswest;
+ tb.dstflag = tz.tz_dsttime;
+ if (copyout((caddr_t)&tb, (caddr_t)uap->tp, sizeof(t)) < 0)
u.u_error = EFAULT;
}
-#endif
+
oalarm()
{
register struct a {
struct timeval atv;
int s = spl7();
- untimeout(unrto, p);
+ untimeout(realitexpire, p);
timerclear(&p->p_realtimer.it_interval);
u.u_r.r_val1 = 0;
if (timerisset(&p->p_realtimer.it_value) &&
}
p->p_realtimer.it_value = time;
p->p_realtimer.it_value.tv_sec += uap->deltat;
- timeout(unrto, p, hzto(&p->p_realtimer.it_value));
+ timeout(realitexpire, p, hzto(&p->p_realtimer.it_value));
splx(s);
}
-
+#endif