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 1.2 2006/05/20 02:42:15 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
  45 #ifdef _KERNEL
  46
  47 /*
  48  * Return TRUE if we are under our reserved low-free-pages threshold
  49  */
  50
  51 static __inline
  52 int
  53 vm_page_count_reserved(void)
  54 {
  55     return (vmstats.v_free_reserved >
  56         (vmstats.v_free_count + vmstats.v_cache_count));
  57 }
  58
  59 /*
  60  * Return TRUE if we are under our severe low-free-pages threshold
  61  *
  62  * This routine is typically used at the user<->system interface to determine
  63  * whether we need to block in order to avoid a low memory deadlock.
  64  */
  65
  66 static __inline
  67 int
  68 vm_page_count_severe(void)
  69 {
  70     return (vmstats.v_free_severe >
  71         (vmstats.v_free_count + vmstats.v_cache_count));
  72 }
  73
  74 /*
  75  * Return TRUE if we are under our minimum low-free-pages threshold.
  76  *
  77  * This routine is typically used within the system to determine whether
  78  * we can execute potentially very expensive code in terms of memory.  It
  79  * is also used by the pageout daemon to calculate when to sleep, when
  80  * to wake waiters up, and when (after making a pass) to become more
  81  * desparate.
  82  */
  83
  84 static __inline
  85 int
  86 vm_page_count_min(void)
  87 {
  88     return (vmstats.v_free_min >
  89         (vmstats.v_free_count + vmstats.v_cache_count));
  90 }
  91
  92 /*
  93  * Return TRUE if we have not reached our free page target during
  94  * free page recovery operations.
  95  */
  96
  97 static __inline
  98 int
  99 vm_page_count_target(void)
 100 {
 101     return (vmstats.v_free_target >
 102         (vmstats.v_free_count + vmstats.v_cache_count));
 103 }
 104
 105 /*
 106  * Return the number of pages we need to free-up or cache
 107  * A positive number indicates that we do not have enough free pages.
 108  */
 109
 110 static __inline
 111 int
 112 vm_paging_target(void)
 113 {
 114     return (
 115         (vmstats.v_free_target + vmstats.v_cache_min) -
 116         (vmstats.v_free_count + vmstats.v_cache_count)
 117     );
 118 }
 119
 120 /*
 121  * Return a positive number if the pagedaemon needs to be woken up.
 122  */
 123
 124 static __inline
 125 int
 126 vm_paging_needed(void)
 127 {
 128     return (
 129         (vmstats.v_free_reserved + vmstats.v_cache_min) >
 130         (vmstats.v_free_count + vmstats.v_cache_count)
 131     );
 132 }
 133
 134 #endif  /* _KERNEL */
 135 #endif  /* _VM_VM_PAGE2_H_ */
 136