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 #ifndef _SYS_SPINLOCK_H_
  51 #include <sys/spinlock.h>
  52 #endif
  53 #ifndef _SYS_SPINLOCK2_H_
  54 #include <sys/spinlock2.h>
  55 #endif
  56
  57 #ifdef _KERNEL
  58
  59 /*
  60  * Return TRUE if we are under our severe low-free-pages threshold
  61  *
  62  * This causes user processes to stall to avoid exhausting memory that
  63  * the kernel might need.
  64  *
  65  * reserved < severe < minimum < target < paging_target
  66  */
  67 static __inline
  68 int
  69 vm_page_count_severe(void)
  70 {
  71     return (vmstats.v_free_severe >
  72             vmstats.v_free_count + vmstats.v_cache_count ||
  73             vmstats.v_free_reserved > vmstats.v_free_count);
  74 }
  75
  76 /*
  77  * Return TRUE if we are under our minimum low-free-pages threshold.
  78  * This activates the pageout demon.  The pageout demon tries to
  79  * reach the target but may stop once it satisfies the minimum.
  80  *
  81  * reserved < severe < minimum < target < paging_target
  82  */
  83 static __inline
  84 int
  85 vm_page_count_min(int donotcount)
  86 {
  87     return (vmstats.v_free_min + donotcount >
  88             (vmstats.v_free_count + vmstats.v_cache_count) ||
  89             vmstats.v_free_reserved > vmstats.v_free_count);
  90 }
  91
  92 /*
  93  * Return TRUE if we are under our free page target.  The pageout demon
  94  * tries to reach the target but may stop once it gets past the min.
  95  */
  96 static __inline
  97 int
  98 vm_page_count_target(void)
  99 {
 100     return (vmstats.v_free_target >
 101             (vmstats.v_free_count + vmstats.v_cache_count) ||
 102             vmstats.v_free_reserved > vmstats.v_free_count);
 103 }
 104
 105 /*
 106  * Return the number of pages the pageout daemon needs to move into the
 107  * cache or free lists.  A negative number means we have sufficient free
 108  * pages.
 109  *
 110  * The target free+cache is greater than vm_page_count_target().  The
 111  * frontend uses vm_page_count_target() while the backend continue freeing
 112  * based on vm_paging_target().
 113  *
 114  * This function DOES NOT return TRUE or FALSE.
 115  */
 116 static __inline
 117 int
 118 vm_paging_target(void)
 119 {
 120     return (
 121         (vmstats.v_free_target + vmstats.v_cache_min) -
 122         (vmstats.v_free_count + vmstats.v_cache_count)
 123     );
 124 }
 125
 126 /*
 127  * Return TRUE if hysteresis dictates we should nominally wakeup the
 128  * pageout daemon to start working on freeing up some memory.  This
 129  * routine should NOT be used to determine when to block on the VM system.
 130  * We want to wakeup the pageout daemon before we might otherwise block.
 131  *
 132  * Paging begins when cache+free drops below cache_min + free_min.
 133  */
 134 static __inline
 135 int
 136 vm_paging_needed(void)
 137 {
 138     if (vmstats.v_free_min + vmstats.v_cache_min >
 139         vmstats.v_free_count + vmstats.v_cache_count) {
 140                 return 1;
 141     }
 142     if (vmstats.v_free_min > vmstats.v_free_count)
 143                 return 1;
 144     return 0;
 145 }
 146
 147 static __inline
 148 void
 149 vm_page_event(vm_page_t m, vm_page_event_t event)
 150 {
 151     if (m->flags & PG_ACTIONLIST)
 152         vm_page_event_internal(m, event);
 153 }
 154
 155 static __inline
 156 void
 157 vm_page_init_action(vm_page_t m, vm_page_action_t action,
 158                     void (*func)(vm_page_t, vm_page_action_t), void *data)
 159 {
 160     action->m = m;
 161     action->func = func;
 162     action->data = data;
 163 }
 164
 165 /*
 166  * Clear dirty bits in the VM page but truncate the
 167  * end to a DEV_BSIZE'd boundary.
 168  *
 169  * Used when reading data in, typically via getpages.
 170  * The partial device block at the end of the truncation
 171  * range should not lose its dirty bit.
 172  *
 173  * NOTE: This function does not clear the pmap modified bit.
 174  */
 175 static __inline
 176 void
 177 vm_page_clear_dirty_end_nonincl(vm_page_t m, int base, int size)
 178 {
 179     size = (base + size) & ~DEV_BMASK;
 180     if (base < size)
 181         vm_page_clear_dirty(m, base, size - base);
 182 }
 183
 184 /*
 185  * Clear dirty bits in the VM page but truncate the
 186  * beginning to a DEV_BSIZE'd boundary.
 187  *
 188  * Used when truncating a buffer.  The partial device
 189  * block at the beginning of the truncation range
 190  * should not lose its dirty bit.
 191  *
 192  * NOTE: This function does not clear the pmap modified bit.
 193  */
 194 static __inline
 195 void
 196 vm_page_clear_dirty_beg_nonincl(vm_page_t m, int base, int size)
 197 {
 198     size += base;
 199     base = (base + DEV_BMASK) & ~DEV_BMASK;
 200     if (base < size)
 201         vm_page_clear_dirty(m, base, size - base);
 202 }
 203
 204 static __inline
 205 void
 206 vm_page_spin_lock(vm_page_t m)
 207 {
 208     spin_pool_lock(m);
 209 }
 210
 211 static __inline
 212 void
 213 vm_page_spin_unlock(vm_page_t m)
 214 {
 215     spin_pool_unlock(m);
 216 }
 217
 218 /*
 219  * Wire a vm_page that is already wired.  Does not require a busied
 220  * page.
 221  */
 222 static __inline
 223 void
 224 vm_page_wire_quick(vm_page_t m)
 225 {
 226     if (atomic_fetchadd_int(&m->wire_count, 1) == 0)
 227         panic("vm_page_wire_quick: wire_count was 0");
 228 }
 229
 230 /*
 231  * Unwire a vm_page quickly, does not require a busied page.
 232  *
 233  * This routine refuses to drop the wire_count to 0 and will return
 234  * TRUE if it would have had to (instead of decrementing it to 0).
 235  * The caller can then busy the page and deal with it.
 236  */
 237 static __inline
 238 int
 239 vm_page_unwire_quick(vm_page_t m)
 240 {
 241     KKASSERT(m->wire_count > 0);
 242     for (;;) {
 243         u_int wire_count = m->wire_count;
 244
 245         cpu_ccfence();
 246         if (wire_count == 1)
 247                 return TRUE;
 248         if (atomic_cmpset_int(&m->wire_count, wire_count, wire_count - 1))
 249                 return FALSE;
 250     }
 251 }
 252
 253 #endif  /* _KERNEL */
 254 #endif  /* _VM_VM_PAGE2_H_ */
 255