Implement a unified run queue and adjust priority levels accordingly.

- All processes go into the same array of queues, with different
  scheduling classes using different portions of the array.  This
  allows user processes to have their priorities propogated up into
  interrupt thread range if need be.
- I chose 64 run queues as an arbitrary number that is greater than
  32.  We used to have 4 separate arrays of 32 queues each, so this
  may not be optimal.  The new run queue code was written with this
  in mind; changing the number of run queues only requires changing
  constants in runq.h and adjusting the priority levels.
- The new run queue code takes the run queue as a parameter.  This
  is intended to be used to create per-cpu run queues.  Implement
  wrappers for compatibility with the old interface which pass in
  the global run queue structure.
- Group the priority level, user priority, native priority (before
  propogation) and the scheduling class into a struct priority.
- Change any hard coded priority levels that I found to use
  symbolic constants (TTIPRI and TTOPRI).
- Remove the curpriority global variable and use that of curproc.
  This was used to detect when a process' priority had lowered and
  it should yield.  We now effectively yield on every interrupt.
- Activate propogate_priority().  It should now have the desired
  effect without needing to also propogate the scheduling class.
- Temporarily comment out the call to vm_page_zero_idle() in the
  idle loop.  It interfered with propogate_priority() because
  the idle process needed to do a non-blocking acquire of Giant
  and then other processes would try to propogate their priority
  onto it.  The idle process should not do anything except idle.
  vm_page_zero_idle() will return in the form of an idle priority
  kernel thread which is woken up at apprioriate times by the vm
  system.
- Update struct kinfo_proc to the new priority interface.  Deliberately
  change its size by adjusting the spare fields.  It remained the same
  size, but the layout has changed, so userland processes that use it
  would parse the data incorrectly.  The size constraint should really
  be changed to an arbitrary version number.  Also add a debug.sizeof
  sysctl node for struct kinfo_proc.

1 files changed, 16 insertions, 58 deletions

diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index be0ba85..694bdf1 100644
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -68,7 +68,6 @@
 static void sched_setup __P((void *dummy));
 SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL)
 
-u_char	curpriority;
 int	hogticks;
 int	lbolt;
 int	sched_quantum;		/* Roundrobin scheduling quantum in ticks. */
@@ -76,7 +75,6 @@ int	sched_quantum;		/* Roundrobin scheduling quantum in ticks. */
 static struct callout schedcpu_callout;
 static struct callout roundrobin_callout;
 
-static int	curpriority_cmp __P((struct proc *p));
 static void	endtsleep __P((void *));
 static void	roundrobin __P((void *arg));
 static void	schedcpu __P((void *arg));
@@ -100,56 +98,16 @@ sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
 SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW,
 	0, sizeof sched_quantum, sysctl_kern_quantum, "I", "");
 
-/*-
- * Compare priorities.  Return:
- *     <0: priority of p < current priority
- *      0: priority of p == current priority
- *     >0: priority of p > current priority
- * The priorities are the normal priorities or the normal realtime priorities
- * if p is on the same scheduler as curproc.  Otherwise the process on the
- * more realtimeish scheduler has lowest priority.  As usual, a higher
- * priority really means a lower priority.
- */
-static int
-curpriority_cmp(p)
-	struct proc *p;
-{
-	int c_class, p_class;
-
-	c_class = RTP_PRIO_BASE(curproc->p_rtprio.type);
-	p_class = RTP_PRIO_BASE(p->p_rtprio.type);
-	if (p_class != c_class)
-		return (p_class - c_class);
-	if (p_class == RTP_PRIO_NORMAL)
-		return (((int)p->p_priority - (int)curpriority) / PPQ);
-	return ((int)p->p_rtprio.prio - (int)curproc->p_rtprio.prio);
-}
-
 /*
  * Arrange to reschedule if necessary, taking the priorities and
  * schedulers into account.
  */
 void
-maybe_resched(chk)
-	struct proc *chk;
+maybe_resched(p)
+	struct proc *p;
 {
-	struct proc *p = curproc; /* XXX */
 
-	/*
-	 * XXX idle scheduler still broken because proccess stays on idle
-	 * scheduler during waits (such as when getting FS locks).  If a
-	 * standard process becomes runaway cpu-bound, the system can lockup
-	 * due to idle-scheduler processes in wakeup never getting any cpu.
-	 */
-	if (p == PCPU_GET(idleproc)) {
-#if 0
-		need_resched();
-#endif
-	} else if (chk == p) {
-		/* We may need to yield if our priority has been raised. */
-		if (curpriority_cmp(chk) > 0)
-			need_resched();
-	} else if (curpriority_cmp(chk) < 0)
+	if (p->p_pri.pri_level < curproc->p_pri.pri_level)
 		need_resched();
 }
 
@@ -325,19 +283,20 @@ schedcpu(arg)
 		p->p_cpticks = 0;
 		p->p_estcpu = decay_cpu(loadfac, p->p_estcpu);
 		resetpriority(p);
-		if (p->p_priority >= PUSER) {
+		if (p->p_pri.pri_level >= PUSER) {
 			if ((p != curproc) &&
 #ifdef SMP
 			    p->p_oncpu == 0xff && 	/* idle */
 #endif
 			    p->p_stat == SRUN &&
 			    (p->p_sflag & PS_INMEM) &&
-			    (p->p_priority / PPQ) != (p->p_usrpri / PPQ)) {
+			    (p->p_pri.pri_level / RQ_PPQ) !=
+			    (p->p_pri.pri_user / RQ_PPQ)) {
 				remrunqueue(p);
-				p->p_priority = p->p_usrpri;
+				p->p_pri.pri_level = p->p_pri.pri_user;
 				setrunqueue(p);
 			} else
-				p->p_priority = p->p_usrpri;
+				p->p_pri.pri_level = p->p_pri.pri_user;
 		}
 		mtx_unlock_spin(&sched_lock);
 		splx(s);
@@ -461,7 +420,7 @@ msleep(ident, mtx, priority, wmesg, timo)
 	p->p_wchan = ident;
 	p->p_wmesg = wmesg;
 	p->p_slptime = 0;
-	p->p_priority = priority & PRIMASK;
+	p->p_pri.pri_level = priority & PRIMASK;
 	CTR4(KTR_PROC, "msleep: proc %p (pid %d, %s), schedlock %p",
 		p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock);
 	TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_slpq);
@@ -503,7 +462,6 @@ msleep(ident, mtx, priority, wmesg, timo)
 	        "msleep resume: proc %p (pid %d, %s), schedlock %p",
 		p, p->p_pid, p->p_comm, (void *) sched_lock.mtx_lock);
 resume:
-	curpriority = p->p_usrpri;
 	splx(s);
 	p->p_sflag &= ~PS_SINTR;
 	if (p->p_sflag & PS_TIMEOUT) {
@@ -671,7 +629,6 @@ mawait(struct mtx *mtx, int priority, int timo)
 		p->p_stats->p_ru.ru_nvcsw++;
 		mi_switch();
 resume:
-		curpriority = p->p_usrpri;
 
 		splx(s);
 		p->p_sflag &= ~PS_SINTR;
@@ -1033,11 +990,12 @@ resetpriority(p)
 	register unsigned int newpriority;
 
 	mtx_lock_spin(&sched_lock);
-	if (p->p_rtprio.type == RTP_PRIO_NORMAL) {
+	if (p->p_pri.pri_class == PRI_TIMESHARE) {
 		newpriority = PUSER + p->p_estcpu / INVERSE_ESTCPU_WEIGHT +
 		    NICE_WEIGHT * (p->p_nice - PRIO_MIN);
-		newpriority = min(newpriority, MAXPRI);
-		p->p_usrpri = newpriority;
+		newpriority = min(max(newpriority, PRI_MIN_TIMESHARE),
+		    PRI_MAX_TIMESHARE);
+		p->p_pri.pri_user = newpriority;
 	}
 	maybe_resched(p);
 	mtx_unlock_spin(&sched_lock);
@@ -1080,8 +1038,8 @@ schedclock(p)
 	p->p_estcpu = ESTCPULIM(p->p_estcpu + 1);
 	if ((p->p_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) {
 		resetpriority(p);
-		if (p->p_priority >= PUSER)
-			p->p_priority = p->p_usrpri;
+		if (p->p_pri.pri_level >= PUSER)
+			p->p_pri.pri_level = p->p_pri.pri_user;
 	}
 }
 
@@ -1098,7 +1056,7 @@ yield(struct proc *p, struct yield_args *uap)
 	s = splhigh();
 	mtx_lock_spin(&sched_lock);
 	DROP_GIANT_NOSWITCH();
-	p->p_priority = MAXPRI;
+	p->p_pri.pri_level = PRI_MAX_TIMESHARE;
 	setrunqueue(p);
 	p->p_stats->p_ru.ru_nvcsw++;
 	mi_switch();