diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
index 18fda31016f2..376af2a5db5d 100644
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -38,7 +38,7 @@
  *
  *	from: @(#)vm_machdep.c	7.3 (Berkeley) 5/13/91
  *	Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
- *	$Id$
+ *	$Id: vm_machdep.c,v 1.75 1997/02/22 09:33:01 peter Exp $
  */
 
 #include "npx.h"
@@ -854,7 +854,22 @@ int
 vm_page_zero_idle() {
 	vm_page_t m;
 	static int free_rover = 0;
-	if ((cnt.v_free_count > cnt.v_interrupt_free_min) &&
+/* XXX
+ * We stop zeroing pages when there are sufficent prezeroed pages.
+ * This threshold isn't really needed, except we want to
+ * bypass unneeded calls to vm_page_list_find, and the
+ * associated cache flush and latency.  The pre-zero will
+ * still be called when there are significantly more
+ * non-prezeroed pages than zeroed pages.  The threshold
+ * of half the number of reserved pages is arbitrary, but
+ * approximately the right amount.  Eventually, we should
+ * perhaps interrupt the zero operation when a process
+ * is found to be ready to run.
+ */
+	if (((cnt.v_free_count - vm_page_zero_count) > (cnt.v_free_reserved / 2)) &&
+#ifdef NOT_NEEDED
+		(cnt.v_free_count > cnt.v_interrupt_free_min) &&
+#endif
 		(m = vm_page_list_find(PQ_FREE, free_rover))) {
 		--(*vm_page_queues[m->queue].lcnt);
 		TAILQ_REMOVE(vm_page_queues[m->queue].pl, m, pageq);
diff --git a/sys/i386/i386/vm_machdep.c b/sys/i386/i386/vm_machdep.c
index 18fda31016f2..376af2a5db5d 100644
--- a/sys/i386/i386/vm_machdep.c
+++ b/sys/i386/i386/vm_machdep.c
@@ -38,7 +38,7 @@
  *
  *	from: @(#)vm_machdep.c	7.3 (Berkeley) 5/13/91
  *	Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
- *	$Id$
+ *	$Id: vm_machdep.c,v 1.75 1997/02/22 09:33:01 peter Exp $
  */
 
 #include "npx.h"
@@ -854,7 +854,22 @@ int
 vm_page_zero_idle() {
 	vm_page_t m;
 	static int free_rover = 0;
-	if ((cnt.v_free_count > cnt.v_interrupt_free_min) &&
+/* XXX
+ * We stop zeroing pages when there are sufficent prezeroed pages.
+ * This threshold isn't really needed, except we want to
+ * bypass unneeded calls to vm_page_list_find, and the
+ * associated cache flush and latency.  The pre-zero will
+ * still be called when there are significantly more
+ * non-prezeroed pages than zeroed pages.  The threshold
+ * of half the number of reserved pages is arbitrary, but
+ * approximately the right amount.  Eventually, we should
+ * perhaps interrupt the zero operation when a process
+ * is found to be ready to run.
+ */
+	if (((cnt.v_free_count - vm_page_zero_count) > (cnt.v_free_reserved / 2)) &&
+#ifdef NOT_NEEDED
+		(cnt.v_free_count > cnt.v_interrupt_free_min) &&
+#endif
 		(m = vm_page_list_find(PQ_FREE, free_rover))) {
 		--(*vm_page_queues[m->queue].lcnt);
 		TAILQ_REMOVE(vm_page_queues[m->queue].pl, m, pageq);