Index: sys/kern/subr_sleepqueue.c
===================================================================
--- sys/kern/subr_sleepqueue.c	(revision 236815)
+++ sys/kern/subr_sleepqueue.c	(working copy)
@@ -374,7 +374,7 @@ sleepq_set_timeout_bt(void *wchan, struct bintime
 	MPASS(TD_ON_SLEEPQ(td));
 	MPASS(td->td_sleepqueue == NULL);
 	MPASS(wchan != NULL);
-	callout_reset_bt_on(&td->td_slpcallout, bt, sleepq_timeout, td, PCPU_GET(cpuid), 0);
+	callout_reset_bt_on(&td->td_slpcallout, bt, sleepq_timeout, td, PCPU_GET(cpuid), 1);
 }
 
 void
Index: sys/kern/kern_timeout.c
===================================================================
--- sys/kern/kern_timeout.c	(revision 236894)
+++ sys/kern/kern_timeout.c	(working copy)
@@ -81,7 +81,7 @@ SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFL
  * TODO:
  *	allocate more timeout table slots when table overflows.
  */
-int callwheelsize, callwheelbits, callwheelmask;
+int callwheelsize, callwheelmask;
 
 /*
  * The callout cpu migration entity represents informations necessary for
@@ -225,10 +225,7 @@ kern_timeout_callwheel_alloc(caddr_t v)
 	/*
 	 * Calculate callout wheel size
 	 */
-	for (callwheelsize = 1, callwheelbits = 0;
-	     callwheelsize < ncallout;
-	     callwheelsize <<= 1, ++callwheelbits)
-		;
+	for (callwheelsize = 1; callwheelsize < ncallout; callwheelsize <<= 1);
 	callwheelmask = callwheelsize - 1;
 
 	cc->cc_callout = (struct callout *)v;
@@ -359,13 +356,11 @@ get_bucket(struct bintime *bt)
 void
 callout_tick(void)
 {
+	struct bintime next, now;
 	struct callout *tmp;
 	struct callout_cpu *cc;
 	struct callout_tailq *sc;
-	struct bintime now;
-	struct bintime limit;
-	struct bintime next;
-	int cpu, first, flag, future, last, need_softclock; 
+	int cpu, first, future, last, need_softclock; 
 
 	/*
 	 * Process callouts at a very low cpu priority, so we don't keep the
@@ -375,8 +370,12 @@ callout_tick(void)
 	cc = CC_SELF();
 	mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET);
 	binuptime(&now);
+	cpu = curcpu;
 	first = callout_hash(&cc->cc_softticks);
 	last = callout_hash(&now);
+	next.sec = -1;
+	next.frac = -1;
+	future = ((last + 256) & callwheelmask); 
 	/* 
 	 * Check if we wrapped around the entire wheel from the last scan.
 	 * In case, we need to scan entirely the wheel for pending callouts.
@@ -389,19 +388,10 @@ callout_tick(void)
 		first &= callwheelmask;
 		last &= callwheelmask;
 	}
-	cpu = curcpu;
-	next.sec = -1;
-	next .frac = -1;
-	limit.sec = 0;
-	limit.frac = 4611686018427250000; /* 1/4 sec */
-	bintime_add(&limit,&now);
-	future = get_bucket(&limit);
-	flag = 0;
 	for (;;) {	
 		sc = &cc->cc_callwheel[first];
 		TAILQ_FOREACH(tmp, sc, c_links.tqe) {
-			if ((!flag || flag == 1) && 
-			    bintime_cmp(&tmp->c_time, &now, <=)) {
+			if (bintime_cmp(&tmp->c_time, &now, <=)) {
 				if (tmp->c_flags & CALLOUT_DIRECT) {
 					tmp->c_func(tmp->c_arg);
 					TAILQ_REMOVE(sc, tmp, c_links.tqe);
@@ -415,8 +405,15 @@ callout_tick(void)
 					need_softclock = 1;
 				}
 			}	
-			if ((flag == 1 || flag == 2)  && 
-			    bintime_cmp(&tmp->c_time, &now, >)) {
+		}	
+		if (first == last)
+			break;
+		first = ((first + 1) & callwheelmask);
+	}		
+	for (;;) {
+		sc = &cc->cc_callwheel[last];
+		TAILQ_FOREACH(tmp, sc, c_links.tqe) {
+			if (bintime_cmp(&tmp->c_time, &now, >)) {
 				if (next.sec == -1 ||
 				    bintime_cmp(&tmp->c_time, &next, <)) {
 					next = tmp->c_time;
@@ -424,16 +421,15 @@ callout_tick(void)
 				}
 			}
 		}
-		if (first == ((last - 1) & callwheelmask)) 
-			flag = 1;
-		if (first == last)
-			flag = 2;
-		if (first == future || next.sec != -1)
+		if ((last == future) || (next.sec != -1))
 			break;
-		first = (first + 1) & callwheelmask;
+		last = ((last + 1) & callwheelmask);
+	}	
+	if (next.sec == -1) { 
+		next.sec = 0;	
+		next.frac = (uint64_t)1 << (64 - 2);	
+		bintime_add(&next, &now);
 	}
-	if (next.sec == -1)  
-		next = limit;
 	cc->cc_firsttick = next;
 	if (callout_new_inserted != NULL) 
 		(*callout_new_inserted)(cpu, next);
Index: sys/dev/hwpmc/hwpmc_intel.c
===================================================================
--- sys/dev/hwpmc/hwpmc_intel.c	(revision 236814)
+++ sys/dev/hwpmc/hwpmc_intel.c	(working copy)
@@ -143,7 +143,6 @@ pmc_intel_initialize(void)
 			nclasses = 5;
 			break;
 		case 0x2A:	/* Per Intel document 253669-039US 05/2011. */
-		case 0x2D:	/* Per Intel document 253669-041US 12/2011. */	
 			cputype = PMC_CPU_INTEL_SANDYBRIDGE;
 			nclasses = 5;
 			break;