sys/vm/vm_reserv.c

   1 /*-
   2  * Copyright (c) 2002-2006 Rice University
   3  * Copyright (c) 2007-2008 Alan L. Cox <alc@cs.rice.edu>
   4  * All rights reserved.
   5  *
   6  * This software was developed for the FreeBSD Project by Alan L. Cox,
   7  * Olivier Crameri, Peter Druschel, Sitaram Iyer, and Juan Navarro.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21  * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
  22  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  24  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
  25  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  26  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
  28  * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 /*
  33  *      Superpage reservation management module
  34  */
  35
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD$");
  38
  39 #include "opt_vm.h"
  40
  41 #include <sys/param.h>
  42 #include <sys/kernel.h>
  43 #include <sys/lock.h>
  44 #include <sys/malloc.h>
  45 #include <sys/mutex.h>
  46 #include <sys/queue.h>
  47 #include <sys/sbuf.h>
  48 #include <sys/sysctl.h>
  49 #include <sys/systm.h>
  50
  51 #include <vm/vm.h>
  52 #include <vm/vm_param.h>
  53 #include <vm/vm_object.h>
  54 #include <vm/vm_page.h>
  55 #include <vm/vm_phys.h>
  56 #include <vm/vm_reserv.h>
  57
  58 /*
  59  * The reservation system supports the speculative allocation of large physical
  60  * pages ("superpages").  Speculative allocation enables the fully-automatic
  61  * utilization of superpages by the virtual memory system.  In other words, no
  62  * programmatic directives are required to use superpages.
  63  */
  64
  65 #if VM_NRESERVLEVEL > 0
  66
  67 /*
  68  * The number of small pages that are contained in a level 0 reservation
  69  */
  70 #define VM_LEVEL_0_NPAGES       (1 << VM_LEVEL_0_ORDER)
  71
  72 /*
  73  * The number of bits by which a physical address is shifted to obtain the
  74  * reservation number
  75  */
  76 #define VM_LEVEL_0_SHIFT        (VM_LEVEL_0_ORDER + PAGE_SHIFT)
  77
  78 /*
  79  * The size of a level 0 reservation in bytes
  80  */
  81 #define VM_LEVEL_0_SIZE         (1 << VM_LEVEL_0_SHIFT)
  82
  83 /*
  84  * Computes the index of the small page underlying the given (object, pindex)
  85  * within the reservation's array of small pages.
  86  */
  87 #define VM_RESERV_INDEX(object, pindex) \
  88     (((object)->pg_color + (pindex)) & (VM_LEVEL_0_NPAGES - 1))
  89
  90 /*
  91  * The reservation structure
  92  *
  93  * A reservation structure is constructed whenever a large physical page is
  94  * speculatively allocated to an object.  The reservation provides the small
  95  * physical pages for the range [pindex, pindex + VM_LEVEL_0_NPAGES) of offsets
  96  * within that object.  The reservation's "popcnt" tracks the number of these
  97  * small physical pages that are in use at any given time.  When and if the
  98  * reservation is not fully utilized, it appears in the queue of partially-
  99  * populated reservations.  The reservation always appears on the containing
 100  * object's list of reservations.
 101  *
 102  * A partially-populated reservation can be broken and reclaimed at any time.
 103  */
 104 struct vm_reserv {
 105         TAILQ_ENTRY(vm_reserv) partpopq;
 106         LIST_ENTRY(vm_reserv) objq;
 107         vm_object_t     object;                 /* containing object */
 108         vm_pindex_t     pindex;                 /* offset within object */
 109         vm_page_t       pages;                  /* first page of a superpage */
 110         int             popcnt;                 /* # of pages in use */
 111         char            inpartpopq;
 112 };
 113
 114 /*
 115  * The reservation array
 116  *
 117  * This array is analoguous in function to vm_page_array.  It differs in the
 118  * respect that it may contain a greater number of useful reservation
 119  * structures than there are (physical) superpages.  These "invalid"
 120  * reservation structures exist to trade-off space for time in the
 121  * implementation of vm_reserv_from_page().  Invalid reservation structures are
 122  * distinguishable from "valid" reservation structures by inspecting the
 123  * reservation's "pages" field.  Invalid reservation structures have a NULL
 124  * "pages" field.
 125  *
 126  * vm_reserv_from_page() maps a small (physical) page to an element of this
 127  * array by computing a physical reservation number from the page's physical
 128  * address.  The physical reservation number is used as the array index.
 129  *
 130  * An "active" reservation is a valid reservation structure that has a non-NULL
 131  * "object" field and a non-zero "popcnt" field.  In other words, every active
 132  * reservation belongs to a particular object.  Moreover, every active
 133  * reservation has an entry in the containing object's list of reservations.
 134  */
 135 static vm_reserv_t vm_reserv_array;
 136
 137 /*
 138  * The partially-populated reservation queue
 139  *
 140  * This queue enables the fast recovery of an unused cached or free small page
 141  * from a partially-populated reservation.  The reservation at the head of
 142  * this queue is the least-recently-changed, partially-populated reservation.
 143  *
 144  * Access to this queue is synchronized by the free page queue lock.
 145  */
 146 static TAILQ_HEAD(, vm_reserv) vm_rvq_partpop =
 147                             TAILQ_HEAD_INITIALIZER(vm_rvq_partpop);
 148
 149 static SYSCTL_NODE(_vm, OID_AUTO, reserv, CTLFLAG_RD, 0, "Reservation Info");
 150
 151 static long vm_reserv_broken;
 152 SYSCTL_LONG(_vm_reserv, OID_AUTO, broken, CTLFLAG_RD,
 153     &vm_reserv_broken, 0, "Cumulative number of broken reservations");
 154
 155 static long vm_reserv_freed;
 156 SYSCTL_LONG(_vm_reserv, OID_AUTO, freed, CTLFLAG_RD,
 157     &vm_reserv_freed, 0, "Cumulative number of freed reservations");
 158
 159 static int sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS);
 160
 161 SYSCTL_OID(_vm_reserv, OID_AUTO, partpopq, CTLTYPE_STRING | CTLFLAG_RD, NULL, 0,
 162     sysctl_vm_reserv_partpopq, "A", "Partially-populated reservation queues");
 163
 164 static long vm_reserv_reclaimed;
 165 SYSCTL_LONG(_vm_reserv, OID_AUTO, reclaimed, CTLFLAG_RD,
 166     &vm_reserv_reclaimed, 0, "Cumulative number of reclaimed reservations");
 167
 168 static void             vm_reserv_depopulate(vm_reserv_t rv);
 169 static vm_reserv_t      vm_reserv_from_page(vm_page_t m);
 170 static boolean_t        vm_reserv_has_pindex(vm_reserv_t rv,
 171                             vm_pindex_t pindex);
 172 static void             vm_reserv_populate(vm_reserv_t rv);
 173 static void             vm_reserv_reclaim(vm_reserv_t rv);
 174
 175 /*
 176  * Describes the current state of the partially-populated reservation queue.
 177  */
 178 static int
 179 sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS)
 180 {
 181         struct sbuf sbuf;
 182         vm_reserv_t rv;
 183         char *cbuf;
 184         const int cbufsize = (VM_NRESERVLEVEL + 1) * 81;
 185         int counter, error, level, unused_pages;
 186
 187         cbuf = malloc(cbufsize, M_TEMP, M_WAITOK | M_ZERO);
 188         sbuf_new(&sbuf, cbuf, cbufsize, SBUF_FIXEDLEN);
 189         sbuf_printf(&sbuf, "\nLEVEL     SIZE  NUMBER\n\n");
 190         for (level = -1; level <= VM_NRESERVLEVEL - 2; level++) {
 191                 counter = 0;
 192                 unused_pages = 0;
 193                 mtx_lock(&vm_page_queue_free_mtx);
 194                 TAILQ_FOREACH(rv, &vm_rvq_partpop/*[level]*/, partpopq) {
 195                         counter++;
 196                         unused_pages += VM_LEVEL_0_NPAGES - rv->popcnt;
 197                 }
 198                 mtx_unlock(&vm_page_queue_free_mtx);
 199                 sbuf_printf(&sbuf, "%5.5d: %6.6dK, %6.6d\n", level,
 200                     unused_pages * (PAGE_SIZE / 1024), counter);
 201         }
 202         sbuf_finish(&sbuf);
 203         error = SYSCTL_OUT(req, sbuf_data(&sbuf), sbuf_len(&sbuf));
 204         sbuf_delete(&sbuf);
 205         free(cbuf, M_TEMP);
 206         return (error);
 207 }
 208
 209 /*
 210  * Reduces the given reservation's population count.  If the population count
 211  * becomes zero, the reservation is destroyed.  Additionally, moves the
 212  * reservation to the tail of the partially-populated reservations queue if the
 213  * population count is non-zero.
 214  *
 215  * The free page queue lock must be held.
 216  */
 217 static void
 218 vm_reserv_depopulate(vm_reserv_t rv)
 219 {
 220
 221         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 222         KASSERT(rv->object != NULL,
 223             ("vm_reserv_depopulate: reserv %p is free", rv));
 224         KASSERT(rv->popcnt > 0,
 225             ("vm_reserv_depopulate: reserv %p's popcnt is corrupted", rv));
 226         if (rv->inpartpopq) {
 227                 TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
 228                 rv->inpartpopq = FALSE;
 229         }
 230         rv->popcnt--;
 231         if (rv->popcnt == 0) {
 232                 LIST_REMOVE(rv, objq);
 233                 rv->object = NULL;
 234                 vm_phys_free_pages(rv->pages, VM_LEVEL_0_ORDER);
 235                 vm_reserv_freed++;
 236         } else {
 237                 rv->inpartpopq = TRUE;
 238                 TAILQ_INSERT_TAIL(&vm_rvq_partpop, rv, partpopq);
 239         }
 240 }
 241
 242 /*
 243  * Returns the reservation to which the given page might belong.
 244  */
 245 static __inline vm_reserv_t
 246 vm_reserv_from_page(vm_page_t m)
 247 {
 248
 249         return (&vm_reserv_array[VM_PAGE_TO_PHYS(m) >> VM_LEVEL_0_SHIFT]);
 250 }
 251
 252 /*
 253  * Returns TRUE if the given reservation contains the given page index and
 254  * FALSE otherwise.
 255  */
 256 static __inline boolean_t
 257 vm_reserv_has_pindex(vm_reserv_t rv, vm_pindex_t pindex)
 258 {
 259
 260         return (((pindex - rv->pindex) & ~(VM_LEVEL_0_NPAGES - 1)) == 0);
 261 }
 262
 263 /*
 264  * Increases the given reservation's population count.  Moves the reservation
 265  * to the tail of the partially-populated reservation queue.
 266  *
 267  * The free page queue must be locked.
 268  */
 269 static void
 270 vm_reserv_populate(vm_reserv_t rv)
 271 {
 272
 273         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 274         KASSERT(rv->object != NULL,
 275             ("vm_reserv_populate: reserv %p is free", rv));
 276         KASSERT(rv->popcnt < VM_LEVEL_0_NPAGES,
 277             ("vm_reserv_populate: reserv %p is already full", rv));
 278         if (rv->inpartpopq) {
 279                 TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
 280                 rv->inpartpopq = FALSE;
 281         }
 282         rv->popcnt++;
 283         if (rv->popcnt < VM_LEVEL_0_NPAGES) {
 284                 rv->inpartpopq = TRUE;
 285                 TAILQ_INSERT_TAIL(&vm_rvq_partpop, rv, partpopq);
 286         }
 287 }
 288
 289 /*
 290  * Allocates a page from an existing or newly-created reservation.
 291  *
 292  * The object and free page queue must be locked.
 293  */
 294 vm_page_t
 295 vm_reserv_alloc_page(vm_object_t object, vm_pindex_t pindex)
 296 {
 297         vm_page_t m, mpred, msucc;
 298         vm_pindex_t first, leftcap, rightcap;
 299         vm_reserv_t rv;
 300
 301         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 302
 303         /*
 304          * Is a reservation fundamentally not possible?
 305          */
 306         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
 307         if (pindex < VM_RESERV_INDEX(object, pindex) ||
 308             pindex >= object->size)
 309                 return (NULL);
 310
 311         /*
 312          * Look for an existing reservation.
 313          */
 314         msucc = NULL;
 315         mpred = object->root;
 316         while (mpred != NULL) {
 317                 KASSERT(mpred->pindex != pindex,
 318                     ("vm_reserv_alloc_page: pindex already allocated"));
 319                 rv = vm_reserv_from_page(mpred);
 320                 if (rv->object == object && vm_reserv_has_pindex(rv, pindex)) {
 321                         m = &rv->pages[VM_RESERV_INDEX(object, pindex)];
 322                         /* Handle vm_page_rename(m, new_object, ...). */
 323                         if ((m->flags & (PG_CACHED | PG_FREE)) == 0)
 324                                 return (NULL);
 325                         vm_reserv_populate(rv);
 326                         return (m);
 327                 } else if (mpred->pindex < pindex) {
 328                         if (msucc != NULL ||
 329                             (msucc = TAILQ_NEXT(mpred, listq)) == NULL)
 330                                 break;
 331                         KASSERT(msucc->pindex != pindex,
 332                             ("vm_reserv_alloc_page: pindex already allocated"));
 333                         rv = vm_reserv_from_page(msucc);
 334                         if (rv->object == object &&
 335                             vm_reserv_has_pindex(rv, pindex)) {
 336                                 m = &rv->pages[VM_RESERV_INDEX(object, pindex)];
 337                                 /* Handle vm_page_rename(m, new_object, ...). */
 338                                 if ((m->flags & (PG_CACHED | PG_FREE)) == 0)
 339                                         return (NULL);
 340                                 vm_reserv_populate(rv);
 341                                 return (m);
 342                         } else if (pindex < msucc->pindex)
 343                                 break;
 344                 } else if (msucc == NULL) {
 345                         msucc = mpred;
 346                         mpred = TAILQ_PREV(msucc, pglist, listq);
 347                         continue;
 348                 }
 349                 msucc = NULL;
 350                 mpred = object->root = vm_page_splay(pindex, object->root);
 351         }
 352
 353         /*
 354          * Determine the first index to the left that can be used.
 355          */
 356         if (mpred == NULL)
 357                 leftcap = 0;
 358         else if ((rv = vm_reserv_from_page(mpred))->object != object)
 359                 leftcap = mpred->pindex + 1;
 360         else
 361                 leftcap = rv->pindex + VM_LEVEL_0_NPAGES;
 362
 363         /*
 364          * Determine the first index to the right that cannot be used.
 365          */
 366         if (msucc == NULL)
 367                 rightcap = pindex + VM_LEVEL_0_NPAGES;
 368         else if ((rv = vm_reserv_from_page(msucc))->object != object)
 369                 rightcap = msucc->pindex;
 370         else
 371                 rightcap = rv->pindex;
 372
 373         /*
 374          * Determine if a reservation fits between the first index to
 375          * the left that can be used and the first index to the right
 376          * that cannot be used.
 377          */
 378         first = pindex - VM_RESERV_INDEX(object, pindex);
 379         if (first < leftcap || first + VM_LEVEL_0_NPAGES > rightcap)
 380                 return (NULL);
 381
 382         /*
 383          * Would a new reservation extend past the end of the given object?
 384          */
 385         if (object->size < first + VM_LEVEL_0_NPAGES) {
 386                 /*
 387                  * Don't allocate a new reservation if the object is a vnode or
 388                  * backed by another object that is a vnode.
 389                  */
 390                 if (object->type == OBJT_VNODE ||
 391                     (object->backing_object != NULL &&
 392                     object->backing_object->type == OBJT_VNODE))
 393                         return (NULL);
 394                 /* Speculate that the object may grow. */
 395         }
 396
 397         /*
 398          * Allocate a new reservation.
 399          */
 400         m = vm_phys_alloc_pages(VM_FREEPOOL_DEFAULT, VM_LEVEL_0_ORDER);
 401         if (m != NULL) {
 402                 rv = vm_reserv_from_page(m);
 403                 KASSERT(rv->pages == m,
 404                     ("vm_reserv_alloc_page: reserv %p's pages is corrupted",
 405                     rv));
 406                 KASSERT(rv->object == NULL,
 407                     ("vm_reserv_alloc_page: reserv %p isn't free", rv));
 408                 LIST_INSERT_HEAD(&object->rvq, rv, objq);
 409                 rv->object = object;
 410                 rv->pindex = first;
 411                 KASSERT(rv->popcnt == 0,
 412                     ("vm_reserv_alloc_page: reserv %p's popcnt is corrupted",
 413                     rv));
 414                 KASSERT(!rv->inpartpopq,
 415                     ("vm_reserv_alloc_page: reserv %p's inpartpopq is TRUE",
 416                     rv));
 417                 vm_reserv_populate(rv);
 418                 m = &rv->pages[VM_RESERV_INDEX(object, pindex)];
 419         }
 420         return (m);
 421 }
 422
 423 /*
 424  * Breaks all reservations belonging to the given object.
 425  */
 426 void
 427 vm_reserv_break_all(vm_object_t object)
 428 {
 429         vm_reserv_t rv;
 430         int i;
 431
 432         mtx_lock(&vm_page_queue_free_mtx);
 433         while ((rv = LIST_FIRST(&object->rvq)) != NULL) {
 434                 KASSERT(rv->object == object,
 435                     ("vm_reserv_break_all: reserv %p is corrupted", rv));
 436                 if (rv->inpartpopq) {
 437                         TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
 438                         rv->inpartpopq = FALSE;
 439                 }
 440                 LIST_REMOVE(rv, objq);
 441                 rv->object = NULL;
 442                 for (i = 0; i < VM_LEVEL_0_NPAGES; i++) {
 443                         if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
 444                                 vm_phys_free_pages(&rv->pages[i], 0);
 445                         else
 446                                 rv->popcnt--;
 447                 }
 448                 KASSERT(rv->popcnt == 0,
 449                     ("vm_reserv_break_all: reserv %p's popcnt is corrupted",
 450                     rv));
 451                 vm_reserv_broken++;
 452         }
 453         mtx_unlock(&vm_page_queue_free_mtx);
 454 }
 455
 456 /*
 457  * Frees the given page if it belongs to a reservation.  Returns TRUE if the
 458  * page is freed and FALSE otherwise.
 459  *
 460  * The free page queue lock must be held.
 461  */
 462 boolean_t
 463 vm_reserv_free_page(vm_page_t m)
 464 {
 465         vm_reserv_t rv;
 466
 467         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 468         rv = vm_reserv_from_page(m);
 469         if (rv->object != NULL) {
 470                 vm_reserv_depopulate(rv);
 471                 return (TRUE);
 472         }
 473         return (FALSE);
 474 }
 475
 476 /*
 477  * Initializes the reservation management system.  Specifically, initializes
 478  * the reservation array.
 479  *
 480  * Requires that vm_page_array and first_page are initialized!
 481  */
 482 void
 483 vm_reserv_init(void)
 484 {
 485         vm_paddr_t paddr;
 486         int i;
 487
 488         /*
 489          * Initialize the reservation array.  Specifically, initialize the
 490          * "pages" field for every element that has an underlying superpage.
 491          */
 492         for (i = 0; phys_avail[i + 1] != 0; i += 2) {
 493                 paddr = roundup2(phys_avail[i], VM_LEVEL_0_SIZE);
 494                 while (paddr + VM_LEVEL_0_SIZE <= phys_avail[i + 1]) {
 495                         vm_reserv_array[paddr >> VM_LEVEL_0_SHIFT].pages =
 496                             PHYS_TO_VM_PAGE(paddr);
 497                         paddr += VM_LEVEL_0_SIZE;
 498                 }
 499         }
 500 }
 501
 502 /*
 503  * Returns a reservation level if the given page belongs to a fully-populated
 504  * reservation and -1 otherwise.
 505  */
 506 int
 507 vm_reserv_level_iffullpop(vm_page_t m)
 508 {
 509         vm_reserv_t rv;
 510
 511         rv = vm_reserv_from_page(m);
 512         return (rv->popcnt == VM_LEVEL_0_NPAGES ? 0 : -1);
 513 }
 514
 515 /*
 516  * Prepare for the reactivation of a cached page.
 517  *
 518  * First, suppose that the given page "m" was allocated individually, i.e., not
 519  * as part of a reservation, and cached.  Then, suppose a reservation
 520  * containing "m" is allocated by the same object.  Although "m" and the
 521  * reservation belong to the same object, "m"'s pindex may not match the
 522  * reservation's.
 523  *
 524  * The free page queue must be locked.
 525  */
 526 boolean_t
 527 vm_reserv_reactivate_page(vm_page_t m)
 528 {
 529         vm_reserv_t rv;
 530         int i, m_index;
 531
 532         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 533         rv = vm_reserv_from_page(m);
 534         if (rv->object == NULL)
 535                 return (FALSE);
 536         KASSERT((m->flags & PG_CACHED) != 0,
 537             ("vm_reserv_uncache_page: page %p is not cached", m));
 538         if (m->object == rv->object &&
 539             m->pindex - rv->pindex == VM_RESERV_INDEX(m->object, m->pindex))
 540                 vm_reserv_populate(rv);
 541         else {
 542                 KASSERT(rv->inpartpopq,
 543                     ("vm_reserv_uncache_page: reserv %p's inpartpopq is FALSE",
 544                     rv));
 545                 TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
 546                 rv->inpartpopq = FALSE;
 547                 LIST_REMOVE(rv, objq);
 548                 rv->object = NULL;
 549                 /* Don't vm_phys_free_pages(m, 0). */
 550                 m_index = m - rv->pages;
 551                 for (i = 0; i < m_index; i++) {
 552                         if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
 553                                 vm_phys_free_pages(&rv->pages[i], 0);
 554                         else
 555                                 rv->popcnt--;
 556                 }
 557                 for (i++; i < VM_LEVEL_0_NPAGES; i++) {
 558                         if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
 559                                 vm_phys_free_pages(&rv->pages[i], 0);
 560                         else
 561                                 rv->popcnt--;
 562                 }
 563                 KASSERT(rv->popcnt == 0,
 564                     ("vm_reserv_uncache_page: reserv %p's popcnt is corrupted",
 565                     rv));
 566                 vm_reserv_broken++;
 567         }
 568         return (TRUE);
 569 }
 570
 571 /*
 572  * Breaks the given partially-populated reservation, releasing its cached and
 573  * free pages to the physical memory allocator.
 574  *
 575  * The free page queue lock must be held.
 576  */
 577 static void
 578 vm_reserv_reclaim(vm_reserv_t rv)
 579 {
 580         int i;
 581
 582         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 583         KASSERT(rv->inpartpopq,
 584             ("vm_reserv_reclaim: reserv %p's inpartpopq is corrupted", rv));
 585         TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
 586         rv->inpartpopq = FALSE;
 587         KASSERT(rv->object != NULL,
 588             ("vm_reserv_reclaim: reserv %p is free", rv));
 589         LIST_REMOVE(rv, objq);
 590         rv->object = NULL;
 591         for (i = 0; i < VM_LEVEL_0_NPAGES; i++) {
 592                 if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
 593                         vm_phys_free_pages(&rv->pages[i], 0);
 594                 else
 595                         rv->popcnt--;
 596         }
 597         KASSERT(rv->popcnt == 0,
 598             ("vm_reserv_reclaim: reserv %p's popcnt is corrupted", rv));
 599         vm_reserv_reclaimed++;
 600 }
 601
 602 /*
 603  * Breaks the reservation at the head of the partially-populated reservation
 604  * queue, releasing its cached and free pages to the physical memory
 605  * allocator.  Returns TRUE if a reservation is broken and FALSE otherwise.
 606  *
 607  * The free page queue lock must be held.
 608  */
 609 boolean_t
 610 vm_reserv_reclaim_inactive(void)
 611 {
 612         vm_reserv_t rv;
 613
 614         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 615         if ((rv = TAILQ_FIRST(&vm_rvq_partpop)) != NULL) {
 616                 vm_reserv_reclaim(rv);
 617                 return (TRUE);
 618         }
 619         return (FALSE);
 620 }
 621
 622 /*
 623  * Searches the partially-populated reservation queue for the least recently
 624  * active reservation with unused pages, i.e., cached or free, that satisfy the
 625  * given request for contiguous physical memory.  If a satisfactory reservation
 626  * is found, it is broken.  Returns TRUE if a reservation is broken and FALSE
 627  * otherwise.
 628  *
 629  * The free page queue lock must be held.
 630  */
 631 boolean_t
 632 vm_reserv_reclaim_contig(vm_paddr_t size, vm_paddr_t low, vm_paddr_t high,
 633     unsigned long alignment, unsigned long boundary)
 634 {
 635         vm_paddr_t pa, pa_length;
 636         vm_reserv_t rv;
 637         int i;
 638
 639         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 640         if (size > VM_LEVEL_0_SIZE - PAGE_SIZE)
 641                 return (FALSE);
 642         TAILQ_FOREACH(rv, &vm_rvq_partpop, partpopq) {
 643                 pa = VM_PAGE_TO_PHYS(&rv->pages[VM_LEVEL_0_NPAGES - 1]);
 644                 if (pa + PAGE_SIZE - size < low) {
 645                         /* this entire reservation is too low; go to next */
 646                         continue;
 647                 }
 648                 pa_length = 0;
 649                 for (i = 0; i < VM_LEVEL_0_NPAGES; i++)
 650                         if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0) {
 651                                 pa_length += PAGE_SIZE;
 652                                 if (pa_length == PAGE_SIZE) {
 653                                         pa = VM_PAGE_TO_PHYS(&rv->pages[i]);
 654                                         if (pa + size > high) {
 655                                                 /* skip to next reservation */
 656                                                 break;
 657                                         } else if (pa < low ||
 658                                             (pa & (alignment - 1)) != 0 ||
 659                                             ((pa ^ (pa + size - 1)) &
 660                                             ~(boundary - 1)) != 0)
 661                                                 pa_length = 0;
 662                                 } else if (pa_length >= size) {
 663                                         vm_reserv_reclaim(rv);
 664                                         return (TRUE);
 665                                 }
 666                         } else
 667                                 pa_length = 0;
 668         }
 669         return (FALSE);
 670 }
 671
 672 /*
 673  * Transfers the reservation underlying the given page to a new object.
 674  *
 675  * The object must be locked.
 676  */
 677 void
 678 vm_reserv_rename(vm_page_t m, vm_object_t new_object, vm_object_t old_object,
 679     vm_pindex_t old_object_offset)
 680 {
 681         vm_reserv_t rv;
 682
 683         VM_OBJECT_LOCK_ASSERT(new_object, MA_OWNED);
 684         rv = vm_reserv_from_page(m);
 685         if (rv->object == old_object) {
 686                 mtx_lock(&vm_page_queue_free_mtx);
 687                 if (rv->object == old_object) {
 688                         LIST_REMOVE(rv, objq);
 689                         LIST_INSERT_HEAD(&new_object->rvq, rv, objq);
 690                         rv->object = new_object;
 691                         rv->pindex -= old_object_offset;
 692                 }
 693                 mtx_unlock(&vm_page_queue_free_mtx);
 694         }
 695 }
 696
 697 /*
 698  * Allocates the virtual and physical memory required by the reservation
 699  * management system's data structures, in particular, the reservation array.
 700  */
 701 vm_paddr_t
 702 vm_reserv_startup(vm_offset_t *vaddr, vm_paddr_t end, vm_paddr_t high_water)
 703 {
 704         vm_paddr_t new_end;
 705         size_t size;
 706
 707         /*
 708          * Calculate the size (in bytes) of the reservation array.  Round up
 709          * from "high_water" because every small page is mapped to an element
 710          * in the reservation array based on its physical address.  Thus, the
 711          * number of elements in the reservation array can be greater than the
 712          * number of superpages.
 713          */
 714         size = howmany(high_water, VM_LEVEL_0_SIZE) * sizeof(struct vm_reserv);
 715
 716         /*
 717          * Allocate and map the physical memory for the reservation array.  The
 718          * next available virtual address is returned by reference.
 719          */
 720         new_end = end - round_page(size);
 721         vm_reserv_array = (void *)(uintptr_t)pmap_map(vaddr, new_end, end,
 722             VM_PROT_READ | VM_PROT_WRITE);
 723         bzero(vm_reserv_array, size);
 724
 725         /*
 726          * Return the next available physical address.
 727          */
 728         return (new_end);
 729 }
 730
 731 #endif  /* VM_NRESERVLEVEL > 0 */