sys/vm/vm_page2.h

   1 /*-
   2  * Copyright (c) 1982, 1986, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)vmmeter.h   8.2 (Berkeley) 7/10/94
  34  * $FreeBSD: src/sys/sys/vmmeter.h,v 1.21.2.2 2002/10/10 19:28:21 dillon Exp $
  35  * $DragonFly: src/sys/vm/vm_page2.h,v 1.3 2008/04/14 20:00:29 dillon Exp $
  36  */
  37
  38 #ifndef _VM_VM_PAGE2_H_
  39 #define _VM_VM_PAGE2_H_
  40
  41 #ifndef _SYS_VMMETER_H_
  42 #include <sys/vmmeter.h>
  43 #endif
  44 #ifndef _SYS_QUEUE_H_
  45 #include <sys/queue.h>
  46 #endif
  47 #ifndef _VM_PAGE_H_
  48 #include <vm/vm_page.h>
  49 #endif
  50
  51 #ifdef _KERNEL
  52
  53 /*
  54  * Return TRUE if we are under our severe low-free-pages threshold
  55  *
  56  * This causes user processes to stall to avoid exhausting memory that
  57  * the kernel might need.
  58  *
  59  * reserved < severe < minimum < target < paging_target
  60  */
  61 static __inline
  62 int
  63 vm_page_count_severe(void)
  64 {
  65     return (vmstats.v_free_severe >
  66             vmstats.v_free_count + vmstats.v_cache_count);
  67 }
  68
  69 /*
  70  * Return TRUE if we are under our minimum low-free-pages threshold.
  71  * This activates the pageout demon.  The pageout demon tries to
  72  * reach the target but may stop once it satisfies the minimum.
  73  *
  74  * reserved < severe < minimum < target < paging_target
  75  */
  76 static __inline
  77 int
  78 vm_page_count_min(int donotcount)
  79 {
  80     return (vmstats.v_free_min + donotcount >
  81             (vmstats.v_free_count + vmstats.v_cache_count) ||
  82             vmstats.v_free_reserved > vmstats.v_free_count);
  83 }
  84
  85 /*
  86  * Return TRUE if we are under our free page target.  The pageout demon
  87  * tries to reach the target but may stop once it gets past the min.
  88  */
  89 static __inline
  90 int
  91 vm_page_count_target(void)
  92 {
  93     return (vmstats.v_free_target >
  94             (vmstats.v_free_count + vmstats.v_cache_count));
  95 }
  96
  97 /*
  98  * Return the number of pages the pageout daemon needs to move into the
  99  * cache or free lists.  A negative number means we have sufficient free
 100  * pages.
 101  */
 102 static __inline
 103 int
 104 vm_paging_target(void)
 105 {
 106     return (
 107         (vmstats.v_free_target + vmstats.v_cache_min) -
 108         (vmstats.v_free_count + vmstats.v_cache_count)
 109     );
 110 }
 111
 112 /*
 113  * Return TRUE if we need to start paging.  This routine should not be
 114  * used to determine when to block on the VM system.  It supplies hysteresis
 115  * to the pageout code.
 116  *
 117  * XXX this triggers a wakeup of the pagedaemon.  As part of its work
 118  * the pagedaemon tries to maintain v_free_reserved worth of truely
 119  * free pages.  Set the trigger point a bit lower so we have some hystereis.
 120  */
 121 static __inline
 122 int
 123 vm_paging_needed(void)
 124 {
 125     int trigger;
 126
 127     trigger = vmstats.v_interrupt_free_min +
 128               (vmstats.v_free_reserved - vmstats.v_interrupt_free_min) / 2;
 129     if (trigger < 10)   /* safety */
 130         trigger = 10;
 131
 132     return (
 133         (vmstats.v_free_min + vmstats.v_cache_min) >
 134         (vmstats.v_free_count + vmstats.v_cache_count) ||
 135         trigger > vmstats.v_free_count
 136     );
 137 }
 138
 139 static __inline
 140 void
 141 vm_page_event(vm_page_t m, vm_page_event_t event)
 142 {
 143     if (LIST_FIRST(&m->action_list))
 144         vm_page_event_internal(m, event);
 145 }
 146
 147 static __inline
 148 void
 149 vm_page_init_action(vm_page_action_t action,
 150                     void (*func)(vm_page_t, vm_page_action_t), void *data)
 151 {
 152     action->func = func;
 153     action->data = data;
 154 }
 155
 156 static __inline
 157 void
 158 vm_page_register_action(vm_page_t m, vm_page_action_t action,
 159                         vm_page_event_t event)
 160 {
 161     action->event = event;
 162     LIST_INSERT_HEAD(&m->action_list, action, entry);
 163 }
 164
 165 static __inline
 166 void
 167 vm_page_unregister_action(vm_page_t m, vm_page_action_t action)
 168 {
 169     if (action->event != VMEVENT_NONE) {
 170         action->event = VMEVENT_NONE;
 171         LIST_REMOVE(action, entry);
 172     }
 173 }
 174
 175 #endif  /* _KERNEL */
 176 #endif  /* _VM_VM_PAGE2_H_ */
 177