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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)vmmeter.h   8.2 (Berkeley) 7/10/94
  30  * $FreeBSD: src/sys/sys/vmmeter.h,v 1.21.2.2 2002/10/10 19:28:21 dillon Exp $
  31  */
  32
  33 #ifndef _VM_VM_PAGE2_H_
  34 #define _VM_VM_PAGE2_H_
  35
  36 #ifdef _KERNEL
  37
  38 #ifndef _SYS_VMMETER_H_
  39 #include <sys/vmmeter.h>
  40 #endif
  41 #ifndef _SYS_QUEUE_H_
  42 #include <sys/queue.h>
  43 #endif
  44 #ifndef _VM_VM_PAGE_H_
  45 #include <vm/vm_page.h>
  46 #endif
  47 #ifndef _SYS_SPINLOCK_H_
  48 #include <sys/spinlock.h>
  49 #endif
  50 #ifndef _SYS_SPINLOCK2_H_
  51 #include <sys/spinlock2.h>
  52 #endif
  53
  54 /*
  55  * SMP NOTE
  56  *
  57  * VM fault rates are highly dependent on SMP locking conflicts and, on
  58  * multi-socket systems, cache mastership changes for globals due to atomic
  59  * ops (even simple atomic_add_*() calls).  Cache mastership changes can
  60  * limit the aggregate fault rate.
  61  *
  62  * For this reason we go through some hoops to access VM statistics for
  63  * low-memory handling, pageout, and other triggers.  Each cpu collects
  64  * adjustments in gd->gd_vmstats_adj.  These get rolled up into the global
  65  * vmstats structure.  The global vmstats structure is then pulled into
  66  * gd->gd_vmstats by each cpu when it needs it.  Critical path checks always
  67  * use the pcpu gd->gd_vmstats structure.
  68  */
  69 /*
  70  * Return TRUE if we are under our severe low-free-pages threshold
  71  *
  72  * This causes user processes to stall to avoid exhausting memory that
  73  * the kernel might need.
  74  *
  75  * reserved < severe < minimum < target < paging_target
  76  */
  77 static __inline
  78 int
  79 vm_page_count_severe(void)
  80 {
  81     globaldata_t gd = mycpu;
  82
  83     return (gd->gd_vmstats.v_free_severe >
  84             gd->gd_vmstats.v_free_count + gd->gd_vmstats.v_cache_count ||
  85             gd->gd_vmstats.v_free_reserved > gd->gd_vmstats.v_free_count);
  86 }
  87
  88 /*
  89  * Return TRUE if we are under our minimum low-free-pages threshold.
  90  * This activates the pageout demon.  The pageout demon tries to
  91  * reach the target but may stop once it satisfies the minimum.
  92  *
  93  * reserved < severe < minimum < target < paging_target
  94  */
  95 static __inline
  96 int
  97 vm_page_count_min(int donotcount)
  98 {
  99     globaldata_t gd = mycpu;
 100
 101     return (gd->gd_vmstats.v_free_min + donotcount >
 102             (gd->gd_vmstats.v_free_count + gd->gd_vmstats.v_cache_count) ||
 103             gd->gd_vmstats.v_free_reserved > gd->gd_vmstats.v_free_count);
 104 }
 105
 106 /*
 107  * Return TRUE if we are under our free page target.  The pageout demon
 108  * tries to reach the target but may stop once it gets past the min.
 109  *
 110  * User threads doing normal allocations might wait based on this
 111  * function but MUST NOT wait in a loop based on this function as the
 112  * VM load may prevent the target from being reached.
 113  */
 114 static __inline
 115 int
 116 vm_page_count_target(void)
 117 {
 118     globaldata_t gd = mycpu;
 119
 120     return (gd->gd_vmstats.v_free_target >
 121             (gd->gd_vmstats.v_free_count + gd->gd_vmstats.v_cache_count) ||
 122             gd->gd_vmstats.v_free_reserved > gd->gd_vmstats.v_free_count);
 123 }
 124
 125 /*
 126  * Return the number of pages the pageout daemon needs to move into the
 127  * cache or free lists.  A negative number means we have sufficient free
 128  * pages.
 129  *
 130  * The target free+cache is greater than vm_page_count_target().  The
 131  * frontend uses vm_page_count_target() while the backend continue freeing
 132  * based on vm_paging_target().
 133  *
 134  * This function DOES NOT return TRUE or FALSE.
 135  */
 136 static __inline
 137 int
 138 vm_paging_target(void)
 139 {
 140     globaldata_t gd = mycpu;
 141
 142     return ((gd->gd_vmstats.v_free_target + gd->gd_vmstats.v_cache_min) -
 143             (gd->gd_vmstats.v_free_count + gd->gd_vmstats.v_cache_count));
 144 }
 145
 146 /*
 147  * Return TRUE if hysteresis dictates we should nominally wakeup the
 148  * pageout daemon to start working on freeing up some memory.  This
 149  * routine should NOT be used to determine when to block on the VM system.
 150  * We want to wakeup the pageout daemon before we might otherwise block.
 151  *
 152  * Paging begins when cache+free drops below cache_min + free_min.
 153  */
 154 static __inline
 155 int
 156 vm_paging_needed(void)
 157 {
 158     globaldata_t gd = mycpu;
 159
 160     if (gd->gd_vmstats.v_free_min + gd->gd_vmstats.v_cache_min >
 161         gd->gd_vmstats.v_free_count + gd->gd_vmstats.v_cache_count) {
 162                 return 1;
 163     }
 164     if (gd->gd_vmstats.v_free_min > gd->gd_vmstats.v_free_count)
 165                 return 1;
 166     return 0;
 167 }
 168
 169 static __inline
 170 void
 171 vm_page_event(vm_page_t m, vm_page_event_t event)
 172 {
 173     if (m->flags & PG_ACTIONLIST)
 174         vm_page_event_internal(m, event);
 175 }
 176
 177 static __inline
 178 void
 179 vm_page_init_action(vm_page_t m, vm_page_action_t action,
 180                     void (*func)(vm_page_t, vm_page_action_t), void *data)
 181 {
 182     action->m = m;
 183     action->func = func;
 184     action->data = data;
 185 }
 186
 187 /*
 188  * Clear dirty bits in the VM page but truncate the
 189  * end to a DEV_BSIZE'd boundary.
 190  *
 191  * Used when reading data in, typically via getpages.
 192  * The partial device block at the end of the truncation
 193  * range should not lose its dirty bit.
 194  *
 195  * NOTE: This function does not clear the pmap modified bit.
 196  */
 197 static __inline
 198 void
 199 vm_page_clear_dirty_end_nonincl(vm_page_t m, int base, int size)
 200 {
 201     size = (base + size) & ~DEV_BMASK;
 202     if (base < size)
 203         vm_page_clear_dirty(m, base, size - base);
 204 }
 205
 206 /*
 207  * Clear dirty bits in the VM page but truncate the
 208  * beginning to a DEV_BSIZE'd boundary.
 209  *
 210  * Used when truncating a buffer.  The partial device
 211  * block at the beginning of the truncation range
 212  * should not lose its dirty bit.
 213  *
 214  * NOTE: This function does not clear the pmap modified bit.
 215  */
 216 static __inline
 217 void
 218 vm_page_clear_dirty_beg_nonincl(vm_page_t m, int base, int size)
 219 {
 220     size += base;
 221     base = (base + DEV_BMASK) & ~DEV_BMASK;
 222     if (base < size)
 223         vm_page_clear_dirty(m, base, size - base);
 224 }
 225
 226 static __inline
 227 void
 228 vm_page_spin_lock(vm_page_t m)
 229 {
 230     spin_lock(&m->spin);
 231 }
 232
 233 static __inline
 234 void
 235 vm_page_spin_unlock(vm_page_t m)
 236 {
 237     spin_unlock(&m->spin);
 238 }
 239
 240 /*
 241  * Wire a vm_page that is already wired.  Does not require a busied
 242  * page.
 243  */
 244 static __inline
 245 void
 246 vm_page_wire_quick(vm_page_t m)
 247 {
 248     if (atomic_fetchadd_int(&m->wire_count, 1) == 0)
 249         panic("vm_page_wire_quick: wire_count was 0");
 250 }
 251
 252 /*
 253  * Unwire a vm_page quickly, does not require a busied page.
 254  *
 255  * This routine refuses to drop the wire_count to 0 and will return
 256  * TRUE if it would have had to (instead of decrementing it to 0).
 257  * The caller can then busy the page and deal with it.
 258  */
 259 static __inline
 260 int
 261 vm_page_unwire_quick(vm_page_t m)
 262 {
 263     KKASSERT(m->wire_count > 0);
 264     for (;;) {
 265         u_int wire_count = m->wire_count;
 266
 267         cpu_ccfence();
 268         if (wire_count == 1)
 269                 return TRUE;
 270         if (atomic_cmpset_int(&m->wire_count, wire_count, wire_count - 1))
 271                 return FALSE;
 272     }
 273 }
 274
 275 /*
 276  *      Functions implemented as macros
 277  */
 278
 279 static __inline void
 280 vm_page_flag_set(vm_page_t m, unsigned int bits)
 281 {
 282         atomic_set_int(&(m)->flags, bits);
 283 }
 284
 285 static __inline void
 286 vm_page_flag_clear(vm_page_t m, unsigned int bits)
 287 {
 288         atomic_clear_int(&(m)->flags, bits);
 289 }
 290
 291 /*
 292  * Wakeup anyone waiting for the page after potentially unbusying
 293  * (hard or soft) or doing other work on a page that might make a
 294  * waiter ready.  The setting of PG_WANTED is integrated into the
 295  * related flags and it can't be set once the flags are already
 296  * clear, so there should be no races here.
 297  */
 298
 299 static __inline void
 300 vm_page_flash(vm_page_t m)
 301 {
 302         if (m->flags & PG_WANTED) {
 303                 vm_page_flag_clear(m, PG_WANTED);
 304                 wakeup(m);
 305         }
 306 }
 307
 308 /*
 309  * Reduce the protection of a page.  This routine never raises the
 310  * protection and therefore can be safely called if the page is already
 311  * at VM_PROT_NONE (it will be a NOP effectively ).
 312  *
 313  * VM_PROT_NONE will remove all user mappings of a page.  This is often
 314  * necessary when a page changes state (for example, turns into a copy-on-write
 315  * page or needs to be frozen for write I/O) in order to force a fault, or
 316  * to force a page's dirty bits to be synchronized and avoid hardware
 317  * (modified/accessed) bit update races with pmap changes.
 318  *
 319  * Since 'prot' is usually a constant, this inline usually winds up optimizing
 320  * out the primary conditional.
 321  *
 322  * WARNING: VM_PROT_NONE can block, but will loop until all mappings have
 323  * been cleared.  Callers should be aware that other page related elements
 324  * might have changed, however.
 325  */
 326 static __inline void
 327 vm_page_protect(vm_page_t m, int prot)
 328 {
 329         KKASSERT(m->flags & PG_BUSY);
 330         if (prot == VM_PROT_NONE) {
 331                 if (m->flags & (PG_WRITEABLE|PG_MAPPED)) {
 332                         pmap_page_protect(m, VM_PROT_NONE);
 333                         /* PG_WRITEABLE & PG_MAPPED cleared by call */
 334                 }
 335         } else if ((prot == VM_PROT_READ) && (m->flags & PG_WRITEABLE)) {
 336                 pmap_page_protect(m, VM_PROT_READ);
 337                 /* PG_WRITEABLE cleared by call */
 338         }
 339 }
 340
 341 /*
 342  * Zero-fill the specified page.  The entire contents of the page will be
 343  * zero'd out.
 344  */
 345 static __inline boolean_t
 346 vm_page_zero_fill(vm_page_t m)
 347 {
 348         pmap_zero_page(VM_PAGE_TO_PHYS(m));
 349         return (TRUE);
 350 }
 351
 352 /*
 353  * Copy the contents of src_m to dest_m.  The pages must be stable but spl
 354  * and other protections depend on context.
 355  */
 356 static __inline void
 357 vm_page_copy(vm_page_t src_m, vm_page_t dest_m)
 358 {
 359         pmap_copy_page(VM_PAGE_TO_PHYS(src_m), VM_PAGE_TO_PHYS(dest_m));
 360         dest_m->valid = VM_PAGE_BITS_ALL;
 361         dest_m->dirty = VM_PAGE_BITS_ALL;
 362 }
 363
 364 /*
 365  * Free a page.  The page must be marked BUSY.
 366  */
 367 static __inline void
 368 vm_page_free(vm_page_t m)
 369 {
 370         vm_page_free_toq(m);
 371 }
 372
 373 /*
 374  * Free a page to the zerod-pages queue.  The caller must ensure that the
 375  * page has been zerod.
 376  */
 377 static __inline void
 378 vm_page_free_zero(vm_page_t m)
 379 {
 380 #ifdef PMAP_DEBUG
 381 #ifdef PHYS_TO_DMAP
 382         char *p = (char *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m));
 383         int i;
 384
 385         for (i = 0; i < PAGE_SIZE; i++) {
 386                 if (p[i] != 0) {
 387                         panic("non-zero page in vm_page_free_zero()");
 388                 }
 389         }
 390 #endif
 391 #endif
 392         vm_page_free_toq(m);
 393 }
 394
 395 /*
 396  * Set page to not be dirty.  Note: does not clear pmap modify bits .
 397  */
 398 static __inline void
 399 vm_page_undirty(vm_page_t m)
 400 {
 401         m->dirty = 0;
 402 }
 403
 404 #endif  /* _KERNEL */
 405 #endif  /* _VM_VM_PAGE2_H_ */
 406