diff -r 650cadd1b283 xen/arch/x86/hvm/vpt.c
--- a/xen/arch/x86/hvm/vpt.c	Fri Nov 02 16:38:11 2007 +0000
+++ b/xen/arch/x86/hvm/vpt.c	Sat Nov 03 16:20:04 2007 -0400
@@ -45,12 +45,20 @@ static void pt_unlock(struct periodic_ti
     spin_unlock(&pt->vcpu->arch.hvm_vcpu.tm_lock);
 }
 
+#define PT_SCHEDULE_SYNC 0
+#define PT_SCHEDULE_ASYNC 1
+int pt_missed_option = PT_SCHEDULE_SYNC;
 static void pt_process_missed_ticks(struct periodic_time *pt)
 {
     s_time_t missed_ticks;
 
-    if ( mode_is(pt->vcpu->domain, no_missed_tick_accounting) )
-        return;
+    if ( mode_is(pt->vcpu->domain, no_missed_tick_accounting)  && (pt_missed_option == PT_SCHEDULE_ASYNC)) {
+	if ( pt->one_shot )
+	    return;
+	if ( (NOW() - pt->scheduled) >= 0 )
+	    pt->scheduled = NOW() + pt->period;
+	return;
+    }
 
     if ( pt->one_shot )
         return;
@@ -60,7 +68,8 @@ static void pt_process_missed_ticks(stru
         return;
 
     missed_ticks = missed_ticks / (s_time_t) pt->period + 1;
-    pt->pending_intr_nr += missed_ticks;
+    if ( !mode_is(pt->vcpu->domain, no_missed_tick_accounting) )
+	pt->pending_intr_nr += missed_ticks;
     pt->scheduled += missed_ticks * pt->period;
 }