Restore hysteresis to vm_zeroidle

[Venkatesh Srinivas]

Hi,

--- vm_zeroidle.c.orig  2010-05-23 18:15:43.000000000 -0400
+++ vm_zeroidle.c       2010-05-24 00:40:23.000000000 -0400
@@ -35,8 +35,6 @@
  *     from: @(#)vm_machdep.c  7.3 (Berkeley) 5/13/91
  *     Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
  * from FreeBSD: .../i386/vm_machdep.c,v 1.165 2001/07/04 23:27:04 dillon
- *
- * $Id: vm_zeroidle.c,v 1.3 2010/05/12 04:50:45 sv5679 Exp $
  */
 #include <sys/param.h>
@@ -67,7 +65,6 @@
 /* Maximum number of pages per second to zero */
 #define NPAGES_RUN     (20000)

-
 static int idlezero_enable = 0;
 TUNABLE_INT("vm.idlezero_enable", &idlezero_enable);
 SYSCTL_INT(_vm, OID_AUTO, idlezero_enable, CTLFLAG_RW, &idlezero_enable, 
0,
@@ -107,8 +104,11 @@
                return (0);
 	if (zero_state && vm_page_zero_count >= 
ZIDLE_LO(vmstats.v_free_count))
                return (0);
-       if (vm_page_zero_count >= ZIDLE_HI(vmstats.v_free_count))
+       if (vm_page_zero_count >= ZIDLE_HI(vmstats.v_free_count)) {
+               zero_state = 1;
                return (0);
+       }
+       zero_state = 0;
        return (1);
 }

Should restore hysteresis to the idle zero logic. The simplest way to do 
this was to add the zero_state set to vm_page_zero_check().

-- vs