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         int counter, error, level, unused_pages;
 184
 185         error = sysctl_wire_old_buffer(req, 0);
 186         if (error != 0)
 187                 return (error);
 188         sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
 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, "%5d: %6dK, %6d\n", level,
 200                     unused_pages * ((int)PAGE_SIZE / 1024), counter);
 201         }
 202         error = sbuf_finish(&sbuf);
 203         sbuf_delete(&sbuf);
 204         return (error);
 205 }
 206
 207 /*
 208  * Reduces the given reservation's population count.  If the population count
 209  * becomes zero, the reservation is destroyed.  Additionally, moves the
 210  * reservation to the tail of the partially-populated reservations queue if the
 211  * population count is non-zero.
 212  *
 213  * The free page queue lock must be held.
 214  */
 215 static void
 216 vm_reserv_depopulate(vm_reserv_t rv)
 217 {
 218
 219         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 220         KASSERT(rv->object != NULL,
 221             ("vm_reserv_depopulate: reserv %p is free", rv));
 222         KASSERT(rv->popcnt > 0,
 223             ("vm_reserv_depopulate: reserv %p's popcnt is corrupted", rv));
 224         if (rv->inpartpopq) {
 225                 TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
 226                 rv->inpartpopq = FALSE;
 227         }
 228         rv->popcnt--;
 229         if (rv->popcnt == 0) {
 230                 LIST_REMOVE(rv, objq);
 231                 rv->object = NULL;
 232                 vm_phys_free_pages(rv->pages, VM_LEVEL_0_ORDER);
 233                 vm_reserv_freed++;
 234         } else {
 235                 rv->inpartpopq = TRUE;
 236                 TAILQ_INSERT_TAIL(&vm_rvq_partpop, rv, partpopq);
 237         }
 238 }
 239
 240 /*
 241  * Returns the reservation to which the given page might belong.
 242  */
 243 static __inline vm_reserv_t
 244 vm_reserv_from_page(vm_page_t m)
 245 {
 246
 247         return (&vm_reserv_array[VM_PAGE_TO_PHYS(m) >> VM_LEVEL_0_SHIFT]);
 248 }
 249
 250 /*
 251  * Returns TRUE if the given reservation contains the given page index and
 252  * FALSE otherwise.
 253  */
 254 static __inline boolean_t
 255 vm_reserv_has_pindex(vm_reserv_t rv, vm_pindex_t pindex)
 256 {
 257
 258         return (((pindex - rv->pindex) & ~(VM_LEVEL_0_NPAGES - 1)) == 0);
 259 }
 260
 261 /*
 262  * Increases the given reservation's population count.  Moves the reservation
 263  * to the tail of the partially-populated reservation queue.
 264  *
 265  * The free page queue must be locked.
 266  */
 267 static void
 268 vm_reserv_populate(vm_reserv_t rv)
 269 {
 270
 271         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 272         KASSERT(rv->object != NULL,
 273             ("vm_reserv_populate: reserv %p is free", rv));
 274         KASSERT(rv->popcnt < VM_LEVEL_0_NPAGES,
 275             ("vm_reserv_populate: reserv %p is already full", rv));
 276         if (rv->inpartpopq) {
 277                 TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
 278                 rv->inpartpopq = FALSE;
 279         }
 280         rv->popcnt++;
 281         if (rv->popcnt < VM_LEVEL_0_NPAGES) {
 282                 rv->inpartpopq = TRUE;
 283                 TAILQ_INSERT_TAIL(&vm_rvq_partpop, rv, partpopq);
 284         }
 285 }
 286
 287 /*
 288  * Allocates a page from an existing or newly-created reservation.
 289  *
 290  * The object and free page queue must be locked.
 291  */
 292 vm_page_t
 293 vm_reserv_alloc_page(vm_object_t object, vm_pindex_t pindex)
 294 {
 295         vm_page_t m, mpred, msucc;
 296         vm_pindex_t first, leftcap, rightcap;
 297         vm_reserv_t rv;
 298
 299         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 300
 301         /*
 302          * Is a reservation fundamentally not possible?
 303          */
 304         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
 305         if (pindex < VM_RESERV_INDEX(object, pindex) ||
 306             pindex >= object->size)
 307                 return (NULL);
 308
 309         /*
 310          * Look for an existing reservation.
 311          */
 312         msucc = NULL;
 313         mpred = object->root;
 314         while (mpred != NULL) {
 315                 KASSERT(mpred->pindex != pindex,
 316                     ("vm_reserv_alloc_page: pindex already allocated"));
 317                 rv = vm_reserv_from_page(mpred);
 318                 if (rv->object == object && vm_reserv_has_pindex(rv, pindex)) {
 319                         m = &rv->pages[VM_RESERV_INDEX(object, pindex)];
 320                         /* Handle vm_page_rename(m, new_object, ...). */
 321                         if ((m->flags & (PG_CACHED | PG_FREE)) == 0)
 322                                 return (NULL);
 323                         vm_reserv_populate(rv);
 324                         return (m);
 325                 } else if (mpred->pindex < pindex) {
 326                         if (msucc != NULL ||
 327                             (msucc = TAILQ_NEXT(mpred, listq)) == NULL)
 328                                 break;
 329                         KASSERT(msucc->pindex != pindex,
 330                             ("vm_reserv_alloc_page: pindex already allocated"));
 331                         rv = vm_reserv_from_page(msucc);
 332                         if (rv->object == object &&
 333                             vm_reserv_has_pindex(rv, pindex)) {
 334                                 m = &rv->pages[VM_RESERV_INDEX(object, pindex)];
 335                                 /* Handle vm_page_rename(m, new_object, ...). */
 336                                 if ((m->flags & (PG_CACHED | PG_FREE)) == 0)
 337                                         return (NULL);
 338                                 vm_reserv_populate(rv);
 339                                 return (m);
 340                         } else if (pindex < msucc->pindex)
 341                                 break;
 342                 } else if (msucc == NULL) {
 343                         msucc = mpred;
 344                         mpred = TAILQ_PREV(msucc, pglist, listq);
 345                         continue;
 346                 }
 347                 msucc = NULL;
 348                 mpred = object->root = vm_page_splay(pindex, object->root);
 349         }
 350
 351         /*
 352          * Determine the first index to the left that can be used.
 353          */
 354         if (mpred == NULL)
 355                 leftcap = 0;
 356         else if ((rv = vm_reserv_from_page(mpred))->object != object)
 357                 leftcap = mpred->pindex + 1;
 358         else
 359                 leftcap = rv->pindex + VM_LEVEL_0_NPAGES;
 360
 361         /*
 362          * Determine the first index to the right that cannot be used.
 363          */
 364         if (msucc == NULL)
 365                 rightcap = pindex + VM_LEVEL_0_NPAGES;
 366         else if ((rv = vm_reserv_from_page(msucc))->object != object)
 367                 rightcap = msucc->pindex;
 368         else
 369                 rightcap = rv->pindex;
 370
 371         /*
 372          * Determine if a reservation fits between the first index to
 373          * the left that can be used and the first index to the right
 374          * that cannot be used.
 375          */
 376         first = pindex - VM_RESERV_INDEX(object, pindex);
 377         if (first < leftcap || first + VM_LEVEL_0_NPAGES > rightcap)
 378                 return (NULL);
 379
 380         /*
 381          * Would a new reservation extend past the end of the given object?
 382          */
 383         if (object->size < first + VM_LEVEL_0_NPAGES) {
 384                 /*
 385                  * Don't allocate a new reservation if the object is a vnode or
 386                  * backed by another object that is a vnode.
 387                  */
 388                 if (object->type == OBJT_VNODE ||
 389                     (object->backing_object != NULL &&
 390                     object->backing_object->type == OBJT_VNODE))
 391                         return (NULL);
 392                 /* Speculate that the object may grow. */
 393         }
 394
 395         /*
 396          * Allocate a new reservation.
 397          */
 398         m = vm_phys_alloc_pages(VM_FREEPOOL_DEFAULT, VM_LEVEL_0_ORDER);
 399         if (m != NULL) {
 400                 rv = vm_reserv_from_page(m);
 401                 KASSERT(rv->pages == m,
 402                     ("vm_reserv_alloc_page: reserv %p's pages is corrupted",
 403                     rv));
 404                 KASSERT(rv->object == NULL,
 405                     ("vm_reserv_alloc_page: reserv %p isn't free", rv));
 406                 LIST_INSERT_HEAD(&object->rvq, rv, objq);
 407                 rv->object = object;
 408                 rv->pindex = first;
 409                 KASSERT(rv->popcnt == 0,
 410                     ("vm_reserv_alloc_page: reserv %p's popcnt is corrupted",
 411                     rv));
 412                 KASSERT(!rv->inpartpopq,
 413                     ("vm_reserv_alloc_page: reserv %p's inpartpopq is TRUE",
 414                     rv));
 415                 vm_reserv_populate(rv);
 416                 m = &rv->pages[VM_RESERV_INDEX(object, pindex)];
 417         }
 418         return (m);
 419 }
 420
 421 /*
 422  * Breaks all reservations belonging to the given object.
 423  */
 424 void
 425 vm_reserv_break_all(vm_object_t object)
 426 {
 427         vm_reserv_t rv;
 428         int i;
 429
 430         mtx_lock(&vm_page_queue_free_mtx);
 431         while ((rv = LIST_FIRST(&object->rvq)) != NULL) {
 432                 KASSERT(rv->object == object,
 433                     ("vm_reserv_break_all: reserv %p is corrupted", rv));
 434                 if (rv->inpartpopq) {
 435                         TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
 436                         rv->inpartpopq = FALSE;
 437                 }
 438                 LIST_REMOVE(rv, objq);
 439                 rv->object = NULL;
 440                 for (i = 0; i < VM_LEVEL_0_NPAGES; i++) {
 441                         if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
 442                                 vm_phys_free_pages(&rv->pages[i], 0);
 443                         else
 444                                 rv->popcnt--;
 445                 }
 446                 KASSERT(rv->popcnt == 0,
 447                     ("vm_reserv_break_all: reserv %p's popcnt is corrupted",
 448                     rv));
 449                 vm_reserv_broken++;
 450         }
 451         mtx_unlock(&vm_page_queue_free_mtx);
 452 }
 453
 454 /*
 455  * Frees the given page if it belongs to a reservation.  Returns TRUE if the
 456  * page is freed and FALSE otherwise.
 457  *
 458  * The free page queue lock must be held.
 459  */
 460 boolean_t
 461 vm_reserv_free_page(vm_page_t m)
 462 {
 463         vm_reserv_t rv;
 464
 465         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 466         rv = vm_reserv_from_page(m);
 467         if (rv->object != NULL) {
 468                 vm_reserv_depopulate(rv);
 469                 return (TRUE);
 470         }
 471         return (FALSE);
 472 }
 473
 474 /*
 475  * Initializes the reservation management system.  Specifically, initializes
 476  * the reservation array.
 477  *
 478  * Requires that vm_page_array and first_page are initialized!
 479  */
 480 void
 481 vm_reserv_init(void)
 482 {
 483         vm_paddr_t paddr;
 484         int i;
 485
 486         /*
 487          * Initialize the reservation array.  Specifically, initialize the
 488          * "pages" field for every element that has an underlying superpage.
 489          */
 490         for (i = 0; phys_avail[i + 1] != 0; i += 2) {
 491                 paddr = roundup2(phys_avail[i], VM_LEVEL_0_SIZE);
 492                 while (paddr + VM_LEVEL_0_SIZE <= phys_avail[i + 1]) {
 493                         vm_reserv_array[paddr >> VM_LEVEL_0_SHIFT].pages =
 494                             PHYS_TO_VM_PAGE(paddr);
 495                         paddr += VM_LEVEL_0_SIZE;
 496                 }
 497         }
 498 }
 499
 500 /*
 501  * Returns a reservation level if the given page belongs to a fully-populated
 502  * reservation and -1 otherwise.
 503  */
 504 int
 505 vm_reserv_level_iffullpop(vm_page_t m)
 506 {
 507         vm_reserv_t rv;
 508
 509         rv = vm_reserv_from_page(m);
 510         return (rv->popcnt == VM_LEVEL_0_NPAGES ? 0 : -1);
 511 }
 512
 513 /*
 514  * Prepare for the reactivation of a cached page.
 515  *
 516  * First, suppose that the given page "m" was allocated individually, i.e., not
 517  * as part of a reservation, and cached.  Then, suppose a reservation
 518  * containing "m" is allocated by the same object.  Although "m" and the
 519  * reservation belong to the same object, "m"'s pindex may not match the
 520  * reservation's.
 521  *
 522  * The free page queue must be locked.
 523  */
 524 boolean_t
 525 vm_reserv_reactivate_page(vm_page_t m)
 526 {
 527         vm_reserv_t rv;
 528         int i, m_index;
 529
 530         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 531         rv = vm_reserv_from_page(m);
 532         if (rv->object == NULL)
 533                 return (FALSE);
 534         KASSERT((m->flags & PG_CACHED) != 0,
 535             ("vm_reserv_uncache_page: page %p is not cached", m));
 536         if (m->object == rv->object &&
 537             m->pindex - rv->pindex == VM_RESERV_INDEX(m->object, m->pindex))
 538                 vm_reserv_populate(rv);
 539         else {
 540                 KASSERT(rv->inpartpopq,
 541                     ("vm_reserv_uncache_page: reserv %p's inpartpopq is FALSE",
 542                     rv));
 543                 TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
 544                 rv->inpartpopq = FALSE;
 545                 LIST_REMOVE(rv, objq);
 546                 rv->object = NULL;
 547                 /* Don't vm_phys_free_pages(m, 0). */
 548                 m_index = m - rv->pages;
 549                 for (i = 0; i < m_index; i++) {
 550                         if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
 551                                 vm_phys_free_pages(&rv->pages[i], 0);
 552                         else
 553                                 rv->popcnt--;
 554                 }
 555                 for (i++; i < VM_LEVEL_0_NPAGES; i++) {
 556                         if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
 557                                 vm_phys_free_pages(&rv->pages[i], 0);
 558                         else
 559                                 rv->popcnt--;
 560                 }
 561                 KASSERT(rv->popcnt == 0,
 562                     ("vm_reserv_uncache_page: reserv %p's popcnt is corrupted",
 563                     rv));
 564                 vm_reserv_broken++;
 565         }
 566         return (TRUE);
 567 }
 568
 569 /*
 570  * Breaks the given partially-populated reservation, releasing its cached and
 571  * free pages to the physical memory allocator.
 572  *
 573  * The free page queue lock must be held.
 574  */
 575 static void
 576 vm_reserv_reclaim(vm_reserv_t rv)
 577 {
 578         int i;
 579
 580         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 581         KASSERT(rv->inpartpopq,
 582             ("vm_reserv_reclaim: reserv %p's inpartpopq is corrupted", rv));
 583         TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
 584         rv->inpartpopq = FALSE;
 585         KASSERT(rv->object != NULL,
 586             ("vm_reserv_reclaim: reserv %p is free", rv));
 587         LIST_REMOVE(rv, objq);
 588         rv->object = NULL;
 589         for (i = 0; i < VM_LEVEL_0_NPAGES; i++) {
 590                 if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0)
 591                         vm_phys_free_pages(&rv->pages[i], 0);
 592                 else
 593                         rv->popcnt--;
 594         }
 595         KASSERT(rv->popcnt == 0,
 596             ("vm_reserv_reclaim: reserv %p's popcnt is corrupted", rv));
 597         vm_reserv_reclaimed++;
 598 }
 599
 600 /*
 601  * Breaks the reservation at the head of the partially-populated reservation
 602  * queue, releasing its cached and free pages to the physical memory
 603  * allocator.  Returns TRUE if a reservation is broken and FALSE otherwise.
 604  *
 605  * The free page queue lock must be held.
 606  */
 607 boolean_t
 608 vm_reserv_reclaim_inactive(void)
 609 {
 610         vm_reserv_t rv;
 611
 612         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 613         if ((rv = TAILQ_FIRST(&vm_rvq_partpop)) != NULL) {
 614                 vm_reserv_reclaim(rv);
 615                 return (TRUE);
 616         }
 617         return (FALSE);
 618 }
 619
 620 /*
 621  * Searches the partially-populated reservation queue for the least recently
 622  * active reservation with unused pages, i.e., cached or free, that satisfy the
 623  * given request for contiguous physical memory.  If a satisfactory reservation
 624  * is found, it is broken.  Returns TRUE if a reservation is broken and FALSE
 625  * otherwise.
 626  *
 627  * The free page queue lock must be held.
 628  */
 629 boolean_t
 630 vm_reserv_reclaim_contig(vm_paddr_t size, vm_paddr_t low, vm_paddr_t high,
 631     unsigned long alignment, unsigned long boundary)
 632 {
 633         vm_paddr_t pa, pa_length;
 634         vm_reserv_t rv;
 635         int i;
 636
 637         mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
 638         if (size > VM_LEVEL_0_SIZE - PAGE_SIZE)
 639                 return (FALSE);
 640         TAILQ_FOREACH(rv, &vm_rvq_partpop, partpopq) {
 641                 pa = VM_PAGE_TO_PHYS(&rv->pages[VM_LEVEL_0_NPAGES - 1]);
 642                 if (pa + PAGE_SIZE - size < low) {
 643                         /* this entire reservation is too low; go to next */
 644                         continue;
 645                 }
 646                 pa_length = 0;
 647                 for (i = 0; i < VM_LEVEL_0_NPAGES; i++)
 648                         if ((rv->pages[i].flags & (PG_CACHED | PG_FREE)) != 0) {
 649                                 pa_length += PAGE_SIZE;
 650                                 if (pa_length == PAGE_SIZE) {
 651                                         pa = VM_PAGE_TO_PHYS(&rv->pages[i]);
 652                                         if (pa + size > high) {
 653                                                 /* skip to next reservation */
 654                                                 break;
 655                                         } else if (pa < low ||
 656                                             (pa & (alignment - 1)) != 0 ||
 657                                             ((pa ^ (pa + size - 1)) &
 658                                             ~(boundary - 1)) != 0)
 659                                                 pa_length = 0;
 660                                 }
 661                                 if (pa_length >= size) {
 662                                         vm_reserv_reclaim(rv);
 663                                         return (TRUE);
 664                                 }
 665                         } else
 666                                 pa_length = 0;
 667         }
 668         return (FALSE);
 669 }
 670
 671 /*
 672  * Transfers the reservation underlying the given page to a new object.
 673  *
 674  * The object must be locked.
 675  */
 676 void
 677 vm_reserv_rename(vm_page_t m, vm_object_t new_object, vm_object_t old_object,
 678     vm_pindex_t old_object_offset)
 679 {
 680         vm_reserv_t rv;
 681
 682         VM_OBJECT_LOCK_ASSERT(new_object, MA_OWNED);
 683         rv = vm_reserv_from_page(m);
 684         if (rv->object == old_object) {
 685                 mtx_lock(&vm_page_queue_free_mtx);
 686                 if (rv->object == old_object) {
 687                         LIST_REMOVE(rv, objq);
 688                         LIST_INSERT_HEAD(&new_object->rvq, rv, objq);
 689                         rv->object = new_object;
 690                         rv->pindex -= old_object_offset;
 691                 }
 692                 mtx_unlock(&vm_page_queue_free_mtx);
 693         }
 694 }
 695
 696 /*
 697  * Allocates the virtual and physical memory required by the reservation
 698  * management system's data structures, in particular, the reservation array.
 699  */
 700 vm_paddr_t
 701 vm_reserv_startup(vm_offset_t *vaddr, vm_paddr_t end, vm_paddr_t high_water)
 702 {
 703         vm_paddr_t new_end;
 704         size_t size;
 705
 706         /*
 707          * Calculate the size (in bytes) of the reservation array.  Round up
 708          * from "high_water" because every small page is mapped to an element
 709          * in the reservation array based on its physical address.  Thus, the
 710          * number of elements in the reservation array can be greater than the
 711          * number of superpages.
 712          */
 713         size = howmany(high_water, VM_LEVEL_0_SIZE) * sizeof(struct vm_reserv);
 714
 715         /*
 716          * Allocate and map the physical memory for the reservation array.  The
 717          * next available virtual address is returned by reference.
 718          */
 719         new_end = end - round_page(size);
 720         vm_reserv_array = (void *)(uintptr_t)pmap_map(vaddr, new_end, end,
 721             VM_PROT_READ | VM_PROT_WRITE);
 722         bzero(vm_reserv_array, size);
 723
 724         /*
 725          * Return the next available physical address.
 726          */
 727         return (new_end);
 728 }
 729
 730 #endif  /* VM_NRESERVLEVEL > 0 */