FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_reserv.c
1 /*-
2 * Copyright (c) 2002-2006 Rice University
3 * Copyright (c) 2007-2011 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 * Any external functions defined by this module are only to be used by the
36 * virtual memory system.
37 */
38
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD: releng/11.0/sys/vm/vm_reserv.c 292469 2015-12-19 18:42:50Z alc $");
41
42 #include "opt_vm.h"
43
44 #include <sys/param.h>
45 #include <sys/kernel.h>
46 #include <sys/lock.h>
47 #include <sys/malloc.h>
48 #include <sys/mutex.h>
49 #include <sys/queue.h>
50 #include <sys/rwlock.h>
51 #include <sys/sbuf.h>
52 #include <sys/sysctl.h>
53 #include <sys/systm.h>
54
55 #include <vm/vm.h>
56 #include <vm/vm_param.h>
57 #include <vm/vm_object.h>
58 #include <vm/vm_page.h>
59 #include <vm/vm_phys.h>
60 #include <vm/vm_radix.h>
61 #include <vm/vm_reserv.h>
62
63 /*
64 * The reservation system supports the speculative allocation of large physical
65 * pages ("superpages"). Speculative allocation enables the fully-automatic
66 * utilization of superpages by the virtual memory system. In other words, no
67 * programmatic directives are required to use superpages.
68 */
69
70 #if VM_NRESERVLEVEL > 0
71
72 /*
73 * The number of small pages that are contained in a level 0 reservation
74 */
75 #define VM_LEVEL_0_NPAGES (1 << VM_LEVEL_0_ORDER)
76
77 /*
78 * The number of bits by which a physical address is shifted to obtain the
79 * reservation number
80 */
81 #define VM_LEVEL_0_SHIFT (VM_LEVEL_0_ORDER + PAGE_SHIFT)
82
83 /*
84 * The size of a level 0 reservation in bytes
85 */
86 #define VM_LEVEL_0_SIZE (1 << VM_LEVEL_0_SHIFT)
87
88 /*
89 * Computes the index of the small page underlying the given (object, pindex)
90 * within the reservation's array of small pages.
91 */
92 #define VM_RESERV_INDEX(object, pindex) \
93 (((object)->pg_color + (pindex)) & (VM_LEVEL_0_NPAGES - 1))
94
95 /*
96 * The size of a population map entry
97 */
98 typedef u_long popmap_t;
99
100 /*
101 * The number of bits in a population map entry
102 */
103 #define NBPOPMAP (NBBY * sizeof(popmap_t))
104
105 /*
106 * The number of population map entries in a reservation
107 */
108 #define NPOPMAP howmany(VM_LEVEL_0_NPAGES, NBPOPMAP)
109
110 /*
111 * Clear a bit in the population map.
112 */
113 static __inline void
114 popmap_clear(popmap_t popmap[], int i)
115 {
116
117 popmap[i / NBPOPMAP] &= ~(1UL << (i % NBPOPMAP));
118 }
119
120 /*
121 * Set a bit in the population map.
122 */
123 static __inline void
124 popmap_set(popmap_t popmap[], int i)
125 {
126
127 popmap[i / NBPOPMAP] |= 1UL << (i % NBPOPMAP);
128 }
129
130 /*
131 * Is a bit in the population map clear?
132 */
133 static __inline boolean_t
134 popmap_is_clear(popmap_t popmap[], int i)
135 {
136
137 return ((popmap[i / NBPOPMAP] & (1UL << (i % NBPOPMAP))) == 0);
138 }
139
140 /*
141 * Is a bit in the population map set?
142 */
143 static __inline boolean_t
144 popmap_is_set(popmap_t popmap[], int i)
145 {
146
147 return ((popmap[i / NBPOPMAP] & (1UL << (i % NBPOPMAP))) != 0);
148 }
149
150 /*
151 * The reservation structure
152 *
153 * A reservation structure is constructed whenever a large physical page is
154 * speculatively allocated to an object. The reservation provides the small
155 * physical pages for the range [pindex, pindex + VM_LEVEL_0_NPAGES) of offsets
156 * within that object. The reservation's "popcnt" tracks the number of these
157 * small physical pages that are in use at any given time. When and if the
158 * reservation is not fully utilized, it appears in the queue of partially-
159 * populated reservations. The reservation always appears on the containing
160 * object's list of reservations.
161 *
162 * A partially-populated reservation can be broken and reclaimed at any time.
163 */
164 struct vm_reserv {
165 TAILQ_ENTRY(vm_reserv) partpopq;
166 LIST_ENTRY(vm_reserv) objq;
167 vm_object_t object; /* containing object */
168 vm_pindex_t pindex; /* offset within object */
169 vm_page_t pages; /* first page of a superpage */
170 int popcnt; /* # of pages in use */
171 char inpartpopq;
172 popmap_t popmap[NPOPMAP]; /* bit vector of used pages */
173 };
174
175 /*
176 * The reservation array
177 *
178 * This array is analoguous in function to vm_page_array. It differs in the
179 * respect that it may contain a greater number of useful reservation
180 * structures than there are (physical) superpages. These "invalid"
181 * reservation structures exist to trade-off space for time in the
182 * implementation of vm_reserv_from_page(). Invalid reservation structures are
183 * distinguishable from "valid" reservation structures by inspecting the
184 * reservation's "pages" field. Invalid reservation structures have a NULL
185 * "pages" field.
186 *
187 * vm_reserv_from_page() maps a small (physical) page to an element of this
188 * array by computing a physical reservation number from the page's physical
189 * address. The physical reservation number is used as the array index.
190 *
191 * An "active" reservation is a valid reservation structure that has a non-NULL
192 * "object" field and a non-zero "popcnt" field. In other words, every active
193 * reservation belongs to a particular object. Moreover, every active
194 * reservation has an entry in the containing object's list of reservations.
195 */
196 static vm_reserv_t vm_reserv_array;
197
198 /*
199 * The partially-populated reservation queue
200 *
201 * This queue enables the fast recovery of an unused cached or free small page
202 * from a partially-populated reservation. The reservation at the head of
203 * this queue is the least-recently-changed, partially-populated reservation.
204 *
205 * Access to this queue is synchronized by the free page queue lock.
206 */
207 static TAILQ_HEAD(, vm_reserv) vm_rvq_partpop =
208 TAILQ_HEAD_INITIALIZER(vm_rvq_partpop);
209
210 static SYSCTL_NODE(_vm, OID_AUTO, reserv, CTLFLAG_RD, 0, "Reservation Info");
211
212 static long vm_reserv_broken;
213 SYSCTL_LONG(_vm_reserv, OID_AUTO, broken, CTLFLAG_RD,
214 &vm_reserv_broken, 0, "Cumulative number of broken reservations");
215
216 static long vm_reserv_freed;
217 SYSCTL_LONG(_vm_reserv, OID_AUTO, freed, CTLFLAG_RD,
218 &vm_reserv_freed, 0, "Cumulative number of freed reservations");
219
220 static int sysctl_vm_reserv_fullpop(SYSCTL_HANDLER_ARGS);
221
222 SYSCTL_PROC(_vm_reserv, OID_AUTO, fullpop, CTLTYPE_INT | CTLFLAG_RD, NULL, 0,
223 sysctl_vm_reserv_fullpop, "I", "Current number of full reservations");
224
225 static int sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS);
226
227 SYSCTL_OID(_vm_reserv, OID_AUTO, partpopq, CTLTYPE_STRING | CTLFLAG_RD, NULL, 0,
228 sysctl_vm_reserv_partpopq, "A", "Partially-populated reservation queues");
229
230 static long vm_reserv_reclaimed;
231 SYSCTL_LONG(_vm_reserv, OID_AUTO, reclaimed, CTLFLAG_RD,
232 &vm_reserv_reclaimed, 0, "Cumulative number of reclaimed reservations");
233
234 static void vm_reserv_break(vm_reserv_t rv, vm_page_t m);
235 static void vm_reserv_depopulate(vm_reserv_t rv, int index);
236 static vm_reserv_t vm_reserv_from_page(vm_page_t m);
237 static boolean_t vm_reserv_has_pindex(vm_reserv_t rv,
238 vm_pindex_t pindex);
239 static void vm_reserv_populate(vm_reserv_t rv, int index);
240 static void vm_reserv_reclaim(vm_reserv_t rv);
241
242 /*
243 * Returns the current number of full reservations.
244 *
245 * Since the number of full reservations is computed without acquiring the
246 * free page queue lock, the returned value may be inexact.
247 */
248 static int
249 sysctl_vm_reserv_fullpop(SYSCTL_HANDLER_ARGS)
250 {
251 vm_paddr_t paddr;
252 struct vm_phys_seg *seg;
253 vm_reserv_t rv;
254 int fullpop, segind;
255
256 fullpop = 0;
257 for (segind = 0; segind < vm_phys_nsegs; segind++) {
258 seg = &vm_phys_segs[segind];
259 paddr = roundup2(seg->start, VM_LEVEL_0_SIZE);
260 while (paddr + VM_LEVEL_0_SIZE <= seg->end) {
261 rv = &vm_reserv_array[paddr >> VM_LEVEL_0_SHIFT];
262 fullpop += rv->popcnt == VM_LEVEL_0_NPAGES;
263 paddr += VM_LEVEL_0_SIZE;
264 }
265 }
266 return (sysctl_handle_int(oidp, &fullpop, 0, req));
267 }
268
269 /*
270 * Describes the current state of the partially-populated reservation queue.
271 */
272 static int
273 sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS)
274 {
275 struct sbuf sbuf;
276 vm_reserv_t rv;
277 int counter, error, level, unused_pages;
278
279 error = sysctl_wire_old_buffer(req, 0);
280 if (error != 0)
281 return (error);
282 sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
283 sbuf_printf(&sbuf, "\nLEVEL SIZE NUMBER\n\n");
284 for (level = -1; level <= VM_NRESERVLEVEL - 2; level++) {
285 counter = 0;
286 unused_pages = 0;
287 mtx_lock(&vm_page_queue_free_mtx);
288 TAILQ_FOREACH(rv, &vm_rvq_partpop/*[level]*/, partpopq) {
289 counter++;
290 unused_pages += VM_LEVEL_0_NPAGES - rv->popcnt;
291 }
292 mtx_unlock(&vm_page_queue_free_mtx);
293 sbuf_printf(&sbuf, "%5d: %6dK, %6d\n", level,
294 unused_pages * ((int)PAGE_SIZE / 1024), counter);
295 }
296 error = sbuf_finish(&sbuf);
297 sbuf_delete(&sbuf);
298 return (error);
299 }
300
301 /*
302 * Reduces the given reservation's population count. If the population count
303 * becomes zero, the reservation is destroyed. Additionally, moves the
304 * reservation to the tail of the partially-populated reservation queue if the
305 * population count is non-zero.
306 *
307 * The free page queue lock must be held.
308 */
309 static void
310 vm_reserv_depopulate(vm_reserv_t rv, int index)
311 {
312
313 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
314 KASSERT(rv->object != NULL,
315 ("vm_reserv_depopulate: reserv %p is free", rv));
316 KASSERT(popmap_is_set(rv->popmap, index),
317 ("vm_reserv_depopulate: reserv %p's popmap[%d] is clear", rv,
318 index));
319 KASSERT(rv->popcnt > 0,
320 ("vm_reserv_depopulate: reserv %p's popcnt is corrupted", rv));
321 if (rv->inpartpopq) {
322 TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
323 rv->inpartpopq = FALSE;
324 } else {
325 KASSERT(rv->pages->psind == 1,
326 ("vm_reserv_depopulate: reserv %p is already demoted",
327 rv));
328 rv->pages->psind = 0;
329 }
330 popmap_clear(rv->popmap, index);
331 rv->popcnt--;
332 if (rv->popcnt == 0) {
333 LIST_REMOVE(rv, objq);
334 rv->object = NULL;
335 vm_phys_free_pages(rv->pages, VM_LEVEL_0_ORDER);
336 vm_reserv_freed++;
337 } else {
338 rv->inpartpopq = TRUE;
339 TAILQ_INSERT_TAIL(&vm_rvq_partpop, rv, partpopq);
340 }
341 }
342
343 /*
344 * Returns the reservation to which the given page might belong.
345 */
346 static __inline vm_reserv_t
347 vm_reserv_from_page(vm_page_t m)
348 {
349
350 return (&vm_reserv_array[VM_PAGE_TO_PHYS(m) >> VM_LEVEL_0_SHIFT]);
351 }
352
353 /*
354 * Returns TRUE if the given reservation contains the given page index and
355 * FALSE otherwise.
356 */
357 static __inline boolean_t
358 vm_reserv_has_pindex(vm_reserv_t rv, vm_pindex_t pindex)
359 {
360
361 return (((pindex - rv->pindex) & ~(VM_LEVEL_0_NPAGES - 1)) == 0);
362 }
363
364 /*
365 * Increases the given reservation's population count. Moves the reservation
366 * to the tail of the partially-populated reservation queue.
367 *
368 * The free page queue must be locked.
369 */
370 static void
371 vm_reserv_populate(vm_reserv_t rv, int index)
372 {
373
374 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
375 KASSERT(rv->object != NULL,
376 ("vm_reserv_populate: reserv %p is free", rv));
377 KASSERT(popmap_is_clear(rv->popmap, index),
378 ("vm_reserv_populate: reserv %p's popmap[%d] is set", rv,
379 index));
380 KASSERT(rv->popcnt < VM_LEVEL_0_NPAGES,
381 ("vm_reserv_populate: reserv %p is already full", rv));
382 KASSERT(rv->pages->psind == 0,
383 ("vm_reserv_populate: reserv %p is already promoted", rv));
384 if (rv->inpartpopq) {
385 TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
386 rv->inpartpopq = FALSE;
387 }
388 popmap_set(rv->popmap, index);
389 rv->popcnt++;
390 if (rv->popcnt < VM_LEVEL_0_NPAGES) {
391 rv->inpartpopq = TRUE;
392 TAILQ_INSERT_TAIL(&vm_rvq_partpop, rv, partpopq);
393 } else
394 rv->pages->psind = 1;
395 }
396
397 /*
398 * Allocates a contiguous set of physical pages of the given size "npages"
399 * from existing or newly created reservations. All of the physical pages
400 * must be at or above the given physical address "low" and below the given
401 * physical address "high". The given value "alignment" determines the
402 * alignment of the first physical page in the set. If the given value
403 * "boundary" is non-zero, then the set of physical pages cannot cross any
404 * physical address boundary that is a multiple of that value. Both
405 * "alignment" and "boundary" must be a power of two.
406 *
407 * The object and free page queue must be locked.
408 */
409 vm_page_t
410 vm_reserv_alloc_contig(vm_object_t object, vm_pindex_t pindex, u_long npages,
411 vm_paddr_t low, vm_paddr_t high, u_long alignment, vm_paddr_t boundary)
412 {
413 vm_paddr_t pa, size;
414 vm_page_t m, m_ret, mpred, msucc;
415 vm_pindex_t first, leftcap, rightcap;
416 vm_reserv_t rv;
417 u_long allocpages, maxpages, minpages;
418 int i, index, n;
419
420 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
421 VM_OBJECT_ASSERT_WLOCKED(object);
422 KASSERT(npages != 0, ("vm_reserv_alloc_contig: npages is 0"));
423
424 /*
425 * Is a reservation fundamentally impossible?
426 */
427 if (pindex < VM_RESERV_INDEX(object, pindex) ||
428 pindex + npages > object->size)
429 return (NULL);
430
431 /*
432 * All reservations of a particular size have the same alignment.
433 * Assuming that the first page is allocated from a reservation, the
434 * least significant bits of its physical address can be determined
435 * from its offset from the beginning of the reservation and the size
436 * of the reservation.
437 *
438 * Could the specified index within a reservation of the smallest
439 * possible size satisfy the alignment and boundary requirements?
440 */
441 pa = VM_RESERV_INDEX(object, pindex) << PAGE_SHIFT;
442 if ((pa & (alignment - 1)) != 0)
443 return (NULL);
444 size = npages << PAGE_SHIFT;
445 if (((pa ^ (pa + size - 1)) & ~(boundary - 1)) != 0)
446 return (NULL);
447
448 /*
449 * Look for an existing reservation.
450 */
451 mpred = vm_radix_lookup_le(&object->rtree, pindex);
452 if (mpred != NULL) {
453 KASSERT(mpred->pindex < pindex,
454 ("vm_reserv_alloc_contig: pindex already allocated"));
455 rv = vm_reserv_from_page(mpred);
456 if (rv->object == object && vm_reserv_has_pindex(rv, pindex))
457 goto found;
458 msucc = TAILQ_NEXT(mpred, listq);
459 } else
460 msucc = TAILQ_FIRST(&object->memq);
461 if (msucc != NULL) {
462 KASSERT(msucc->pindex > pindex,
463 ("vm_reserv_alloc_contig: pindex already allocated"));
464 rv = vm_reserv_from_page(msucc);
465 if (rv->object == object && vm_reserv_has_pindex(rv, pindex))
466 goto found;
467 }
468
469 /*
470 * Could at least one reservation fit between the first index to the
471 * left that can be used ("leftcap") and the first index to the right
472 * that cannot be used ("rightcap")?
473 */
474 first = pindex - VM_RESERV_INDEX(object, pindex);
475 if (mpred != NULL) {
476 if ((rv = vm_reserv_from_page(mpred))->object != object)
477 leftcap = mpred->pindex + 1;
478 else
479 leftcap = rv->pindex + VM_LEVEL_0_NPAGES;
480 if (leftcap > first)
481 return (NULL);
482 }
483 minpages = VM_RESERV_INDEX(object, pindex) + npages;
484 maxpages = roundup2(minpages, VM_LEVEL_0_NPAGES);
485 allocpages = maxpages;
486 if (msucc != NULL) {
487 if ((rv = vm_reserv_from_page(msucc))->object != object)
488 rightcap = msucc->pindex;
489 else
490 rightcap = rv->pindex;
491 if (first + maxpages > rightcap) {
492 if (maxpages == VM_LEVEL_0_NPAGES)
493 return (NULL);
494
495 /*
496 * At least one reservation will fit between "leftcap"
497 * and "rightcap". However, a reservation for the
498 * last of the requested pages will not fit. Reduce
499 * the size of the upcoming allocation accordingly.
500 */
501 allocpages = minpages;
502 }
503 }
504
505 /*
506 * Would the last new reservation extend past the end of the object?
507 */
508 if (first + maxpages > object->size) {
509 /*
510 * Don't allocate the last new reservation if the object is a
511 * vnode or backed by another object that is a vnode.
512 */
513 if (object->type == OBJT_VNODE ||
514 (object->backing_object != NULL &&
515 object->backing_object->type == OBJT_VNODE)) {
516 if (maxpages == VM_LEVEL_0_NPAGES)
517 return (NULL);
518 allocpages = minpages;
519 }
520 /* Speculate that the object may grow. */
521 }
522
523 /*
524 * Allocate the physical pages. The alignment and boundary specified
525 * for this allocation may be different from the alignment and
526 * boundary specified for the requested pages. For instance, the
527 * specified index may not be the first page within the first new
528 * reservation.
529 */
530 m = vm_phys_alloc_contig(allocpages, low, high, ulmax(alignment,
531 VM_LEVEL_0_SIZE), boundary > VM_LEVEL_0_SIZE ? boundary : 0);
532 if (m == NULL)
533 return (NULL);
534
535 /*
536 * The allocated physical pages always begin at a reservation
537 * boundary, but they do not always end at a reservation boundary.
538 * Initialize every reservation that is completely covered by the
539 * allocated physical pages.
540 */
541 m_ret = NULL;
542 index = VM_RESERV_INDEX(object, pindex);
543 do {
544 rv = vm_reserv_from_page(m);
545 KASSERT(rv->pages == m,
546 ("vm_reserv_alloc_contig: reserv %p's pages is corrupted",
547 rv));
548 KASSERT(rv->object == NULL,
549 ("vm_reserv_alloc_contig: reserv %p isn't free", rv));
550 LIST_INSERT_HEAD(&object->rvq, rv, objq);
551 rv->object = object;
552 rv->pindex = first;
553 KASSERT(rv->popcnt == 0,
554 ("vm_reserv_alloc_contig: reserv %p's popcnt is corrupted",
555 rv));
556 KASSERT(!rv->inpartpopq,
557 ("vm_reserv_alloc_contig: reserv %p's inpartpopq is TRUE",
558 rv));
559 for (i = 0; i < NPOPMAP; i++)
560 KASSERT(rv->popmap[i] == 0,
561 ("vm_reserv_alloc_contig: reserv %p's popmap is corrupted",
562 rv));
563 n = ulmin(VM_LEVEL_0_NPAGES - index, npages);
564 for (i = 0; i < n; i++)
565 vm_reserv_populate(rv, index + i);
566 npages -= n;
567 if (m_ret == NULL) {
568 m_ret = &rv->pages[index];
569 index = 0;
570 }
571 m += VM_LEVEL_0_NPAGES;
572 first += VM_LEVEL_0_NPAGES;
573 allocpages -= VM_LEVEL_0_NPAGES;
574 } while (allocpages >= VM_LEVEL_0_NPAGES);
575 return (m_ret);
576
577 /*
578 * Found a matching reservation.
579 */
580 found:
581 index = VM_RESERV_INDEX(object, pindex);
582 /* Does the allocation fit within the reservation? */
583 if (index + npages > VM_LEVEL_0_NPAGES)
584 return (NULL);
585 m = &rv->pages[index];
586 pa = VM_PAGE_TO_PHYS(m);
587 if (pa < low || pa + size > high || (pa & (alignment - 1)) != 0 ||
588 ((pa ^ (pa + size - 1)) & ~(boundary - 1)) != 0)
589 return (NULL);
590 /* Handle vm_page_rename(m, new_object, ...). */
591 for (i = 0; i < npages; i++)
592 if (popmap_is_set(rv->popmap, index + i))
593 return (NULL);
594 for (i = 0; i < npages; i++)
595 vm_reserv_populate(rv, index + i);
596 return (m);
597 }
598
599 /*
600 * Allocates a page from an existing or newly-created reservation.
601 *
602 * The page "mpred" must immediately precede the offset "pindex" within the
603 * specified object.
604 *
605 * The object and free page queue must be locked.
606 */
607 vm_page_t
608 vm_reserv_alloc_page(vm_object_t object, vm_pindex_t pindex, vm_page_t mpred)
609 {
610 vm_page_t m, msucc;
611 vm_pindex_t first, leftcap, rightcap;
612 vm_reserv_t rv;
613 int i, index;
614
615 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
616 VM_OBJECT_ASSERT_WLOCKED(object);
617
618 /*
619 * Is a reservation fundamentally impossible?
620 */
621 if (pindex < VM_RESERV_INDEX(object, pindex) ||
622 pindex >= object->size)
623 return (NULL);
624
625 /*
626 * Look for an existing reservation.
627 */
628 if (mpred != NULL) {
629 KASSERT(mpred->object == object,
630 ("vm_reserv_alloc_page: object doesn't contain mpred"));
631 KASSERT(mpred->pindex < pindex,
632 ("vm_reserv_alloc_page: mpred doesn't precede pindex"));
633 rv = vm_reserv_from_page(mpred);
634 if (rv->object == object && vm_reserv_has_pindex(rv, pindex))
635 goto found;
636 msucc = TAILQ_NEXT(mpred, listq);
637 } else
638 msucc = TAILQ_FIRST(&object->memq);
639 if (msucc != NULL) {
640 KASSERT(msucc->pindex > pindex,
641 ("vm_reserv_alloc_page: msucc doesn't succeed pindex"));
642 rv = vm_reserv_from_page(msucc);
643 if (rv->object == object && vm_reserv_has_pindex(rv, pindex))
644 goto found;
645 }
646
647 /*
648 * Could a reservation fit between the first index to the left that
649 * can be used and the first index to the right that cannot be used?
650 */
651 first = pindex - VM_RESERV_INDEX(object, pindex);
652 if (mpred != NULL) {
653 if ((rv = vm_reserv_from_page(mpred))->object != object)
654 leftcap = mpred->pindex + 1;
655 else
656 leftcap = rv->pindex + VM_LEVEL_0_NPAGES;
657 if (leftcap > first)
658 return (NULL);
659 }
660 if (msucc != NULL) {
661 if ((rv = vm_reserv_from_page(msucc))->object != object)
662 rightcap = msucc->pindex;
663 else
664 rightcap = rv->pindex;
665 if (first + VM_LEVEL_0_NPAGES > rightcap)
666 return (NULL);
667 }
668
669 /*
670 * Would a new reservation extend past the end of the object?
671 */
672 if (first + VM_LEVEL_0_NPAGES > object->size) {
673 /*
674 * Don't allocate a new reservation if the object is a vnode or
675 * backed by another object that is a vnode.
676 */
677 if (object->type == OBJT_VNODE ||
678 (object->backing_object != NULL &&
679 object->backing_object->type == OBJT_VNODE))
680 return (NULL);
681 /* Speculate that the object may grow. */
682 }
683
684 /*
685 * Allocate and populate the new reservation.
686 */
687 m = vm_phys_alloc_pages(VM_FREEPOOL_DEFAULT, VM_LEVEL_0_ORDER);
688 if (m == NULL)
689 return (NULL);
690 rv = vm_reserv_from_page(m);
691 KASSERT(rv->pages == m,
692 ("vm_reserv_alloc_page: reserv %p's pages is corrupted", rv));
693 KASSERT(rv->object == NULL,
694 ("vm_reserv_alloc_page: reserv %p isn't free", rv));
695 LIST_INSERT_HEAD(&object->rvq, rv, objq);
696 rv->object = object;
697 rv->pindex = first;
698 KASSERT(rv->popcnt == 0,
699 ("vm_reserv_alloc_page: reserv %p's popcnt is corrupted", rv));
700 KASSERT(!rv->inpartpopq,
701 ("vm_reserv_alloc_page: reserv %p's inpartpopq is TRUE", rv));
702 for (i = 0; i < NPOPMAP; i++)
703 KASSERT(rv->popmap[i] == 0,
704 ("vm_reserv_alloc_page: reserv %p's popmap is corrupted",
705 rv));
706 index = VM_RESERV_INDEX(object, pindex);
707 vm_reserv_populate(rv, index);
708 return (&rv->pages[index]);
709
710 /*
711 * Found a matching reservation.
712 */
713 found:
714 index = VM_RESERV_INDEX(object, pindex);
715 m = &rv->pages[index];
716 /* Handle vm_page_rename(m, new_object, ...). */
717 if (popmap_is_set(rv->popmap, index))
718 return (NULL);
719 vm_reserv_populate(rv, index);
720 return (m);
721 }
722
723 /*
724 * Breaks the given reservation. Except for the specified cached or free
725 * page, all cached and free pages in the reservation are returned to the
726 * physical memory allocator. The reservation's population count and map are
727 * reset to their initial state.
728 *
729 * The given reservation must not be in the partially-populated reservation
730 * queue. The free page queue lock must be held.
731 */
732 static void
733 vm_reserv_break(vm_reserv_t rv, vm_page_t m)
734 {
735 int begin_zeroes, hi, i, lo;
736
737 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
738 KASSERT(rv->object != NULL,
739 ("vm_reserv_break: reserv %p is free", rv));
740 KASSERT(!rv->inpartpopq,
741 ("vm_reserv_break: reserv %p's inpartpopq is TRUE", rv));
742 LIST_REMOVE(rv, objq);
743 rv->object = NULL;
744 if (m != NULL) {
745 /*
746 * Since the reservation is being broken, there is no harm in
747 * abusing the population map to stop "m" from being returned
748 * to the physical memory allocator.
749 */
750 i = m - rv->pages;
751 KASSERT(popmap_is_clear(rv->popmap, i),
752 ("vm_reserv_break: reserv %p's popmap is corrupted", rv));
753 popmap_set(rv->popmap, i);
754 rv->popcnt++;
755 }
756 i = hi = 0;
757 do {
758 /* Find the next 0 bit. Any previous 0 bits are < "hi". */
759 lo = ffsl(~(((1UL << hi) - 1) | rv->popmap[i]));
760 if (lo == 0) {
761 /* Redundantly clears bits < "hi". */
762 rv->popmap[i] = 0;
763 rv->popcnt -= NBPOPMAP - hi;
764 while (++i < NPOPMAP) {
765 lo = ffsl(~rv->popmap[i]);
766 if (lo == 0) {
767 rv->popmap[i] = 0;
768 rv->popcnt -= NBPOPMAP;
769 } else
770 break;
771 }
772 if (i == NPOPMAP)
773 break;
774 hi = 0;
775 }
776 KASSERT(lo > 0, ("vm_reserv_break: lo is %d", lo));
777 /* Convert from ffsl() to ordinary bit numbering. */
778 lo--;
779 if (lo > 0) {
780 /* Redundantly clears bits < "hi". */
781 rv->popmap[i] &= ~((1UL << lo) - 1);
782 rv->popcnt -= lo - hi;
783 }
784 begin_zeroes = NBPOPMAP * i + lo;
785 /* Find the next 1 bit. */
786 do
787 hi = ffsl(rv->popmap[i]);
788 while (hi == 0 && ++i < NPOPMAP);
789 if (i != NPOPMAP)
790 /* Convert from ffsl() to ordinary bit numbering. */
791 hi--;
792 vm_phys_free_contig(&rv->pages[begin_zeroes], NBPOPMAP * i +
793 hi - begin_zeroes);
794 } while (i < NPOPMAP);
795 KASSERT(rv->popcnt == 0,
796 ("vm_reserv_break: reserv %p's popcnt is corrupted", rv));
797 vm_reserv_broken++;
798 }
799
800 /*
801 * Breaks all reservations belonging to the given object.
802 */
803 void
804 vm_reserv_break_all(vm_object_t object)
805 {
806 vm_reserv_t rv;
807
808 mtx_lock(&vm_page_queue_free_mtx);
809 while ((rv = LIST_FIRST(&object->rvq)) != NULL) {
810 KASSERT(rv->object == object,
811 ("vm_reserv_break_all: reserv %p is corrupted", rv));
812 if (rv->inpartpopq) {
813 TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
814 rv->inpartpopq = FALSE;
815 }
816 vm_reserv_break(rv, NULL);
817 }
818 mtx_unlock(&vm_page_queue_free_mtx);
819 }
820
821 /*
822 * Frees the given page if it belongs to a reservation. Returns TRUE if the
823 * page is freed and FALSE otherwise.
824 *
825 * The free page queue lock must be held.
826 */
827 boolean_t
828 vm_reserv_free_page(vm_page_t m)
829 {
830 vm_reserv_t rv;
831
832 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
833 rv = vm_reserv_from_page(m);
834 if (rv->object == NULL)
835 return (FALSE);
836 vm_reserv_depopulate(rv, m - rv->pages);
837 return (TRUE);
838 }
839
840 /*
841 * Initializes the reservation management system. Specifically, initializes
842 * the reservation array.
843 *
844 * Requires that vm_page_array and first_page are initialized!
845 */
846 void
847 vm_reserv_init(void)
848 {
849 vm_paddr_t paddr;
850 struct vm_phys_seg *seg;
851 int segind;
852
853 /*
854 * Initialize the reservation array. Specifically, initialize the
855 * "pages" field for every element that has an underlying superpage.
856 */
857 for (segind = 0; segind < vm_phys_nsegs; segind++) {
858 seg = &vm_phys_segs[segind];
859 paddr = roundup2(seg->start, VM_LEVEL_0_SIZE);
860 while (paddr + VM_LEVEL_0_SIZE <= seg->end) {
861 vm_reserv_array[paddr >> VM_LEVEL_0_SHIFT].pages =
862 PHYS_TO_VM_PAGE(paddr);
863 paddr += VM_LEVEL_0_SIZE;
864 }
865 }
866 }
867
868 /*
869 * Returns true if the given page belongs to a reservation and that page is
870 * free. Otherwise, returns false.
871 */
872 bool
873 vm_reserv_is_page_free(vm_page_t m)
874 {
875 vm_reserv_t rv;
876
877 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
878 rv = vm_reserv_from_page(m);
879 if (rv->object == NULL)
880 return (false);
881 return (popmap_is_clear(rv->popmap, m - rv->pages));
882 }
883
884 /*
885 * If the given page belongs to a reservation, returns the level of that
886 * reservation. Otherwise, returns -1.
887 */
888 int
889 vm_reserv_level(vm_page_t m)
890 {
891 vm_reserv_t rv;
892
893 rv = vm_reserv_from_page(m);
894 return (rv->object != NULL ? 0 : -1);
895 }
896
897 /*
898 * Returns a reservation level if the given page belongs to a fully-populated
899 * reservation and -1 otherwise.
900 */
901 int
902 vm_reserv_level_iffullpop(vm_page_t m)
903 {
904 vm_reserv_t rv;
905
906 rv = vm_reserv_from_page(m);
907 return (rv->popcnt == VM_LEVEL_0_NPAGES ? 0 : -1);
908 }
909
910 /*
911 * Prepare for the reactivation of a cached page.
912 *
913 * First, suppose that the given page "m" was allocated individually, i.e., not
914 * as part of a reservation, and cached. Then, suppose a reservation
915 * containing "m" is allocated by the same object. Although "m" and the
916 * reservation belong to the same object, "m"'s pindex may not match the
917 * reservation's.
918 *
919 * The free page queue must be locked.
920 */
921 boolean_t
922 vm_reserv_reactivate_page(vm_page_t m)
923 {
924 vm_reserv_t rv;
925 int index;
926
927 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
928 rv = vm_reserv_from_page(m);
929 if (rv->object == NULL)
930 return (FALSE);
931 KASSERT((m->flags & PG_CACHED) != 0,
932 ("vm_reserv_reactivate_page: page %p is not cached", m));
933 if (m->object == rv->object &&
934 m->pindex - rv->pindex == (index = VM_RESERV_INDEX(m->object,
935 m->pindex)))
936 vm_reserv_populate(rv, index);
937 else {
938 KASSERT(rv->inpartpopq,
939 ("vm_reserv_reactivate_page: reserv %p's inpartpopq is FALSE",
940 rv));
941 TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
942 rv->inpartpopq = FALSE;
943 /* Don't release "m" to the physical memory allocator. */
944 vm_reserv_break(rv, m);
945 }
946 return (TRUE);
947 }
948
949 /*
950 * Breaks the given partially-populated reservation, releasing its cached and
951 * free pages to the physical memory allocator.
952 *
953 * The free page queue lock must be held.
954 */
955 static void
956 vm_reserv_reclaim(vm_reserv_t rv)
957 {
958
959 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
960 KASSERT(rv->inpartpopq,
961 ("vm_reserv_reclaim: reserv %p's inpartpopq is FALSE", rv));
962 TAILQ_REMOVE(&vm_rvq_partpop, rv, partpopq);
963 rv->inpartpopq = FALSE;
964 vm_reserv_break(rv, NULL);
965 vm_reserv_reclaimed++;
966 }
967
968 /*
969 * Breaks the reservation at the head of the partially-populated reservation
970 * queue, releasing its cached and free pages to the physical memory
971 * allocator. Returns TRUE if a reservation is broken and FALSE otherwise.
972 *
973 * The free page queue lock must be held.
974 */
975 boolean_t
976 vm_reserv_reclaim_inactive(void)
977 {
978 vm_reserv_t rv;
979
980 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
981 if ((rv = TAILQ_FIRST(&vm_rvq_partpop)) != NULL) {
982 vm_reserv_reclaim(rv);
983 return (TRUE);
984 }
985 return (FALSE);
986 }
987
988 /*
989 * Searches the partially-populated reservation queue for the least recently
990 * active reservation with unused pages, i.e., cached or free, that satisfy the
991 * given request for contiguous physical memory. If a satisfactory reservation
992 * is found, it is broken. Returns TRUE if a reservation is broken and FALSE
993 * otherwise.
994 *
995 * The free page queue lock must be held.
996 */
997 boolean_t
998 vm_reserv_reclaim_contig(u_long npages, vm_paddr_t low, vm_paddr_t high,
999 u_long alignment, vm_paddr_t boundary)
1000 {
1001 vm_paddr_t pa, size;
1002 vm_reserv_t rv;
1003 int hi, i, lo, low_index, next_free;
1004
1005 mtx_assert(&vm_page_queue_free_mtx, MA_OWNED);
1006 if (npages > VM_LEVEL_0_NPAGES - 1)
1007 return (FALSE);
1008 size = npages << PAGE_SHIFT;
1009 TAILQ_FOREACH(rv, &vm_rvq_partpop, partpopq) {
1010 pa = VM_PAGE_TO_PHYS(&rv->pages[VM_LEVEL_0_NPAGES - 1]);
1011 if (pa + PAGE_SIZE - size < low) {
1012 /* This entire reservation is too low; go to next. */
1013 continue;
1014 }
1015 pa = VM_PAGE_TO_PHYS(&rv->pages[0]);
1016 if (pa + size > high) {
1017 /* This entire reservation is too high; go to next. */
1018 continue;
1019 }
1020 if (pa < low) {
1021 /* Start the search for free pages at "low". */
1022 low_index = (low + PAGE_MASK - pa) >> PAGE_SHIFT;
1023 i = low_index / NBPOPMAP;
1024 hi = low_index % NBPOPMAP;
1025 } else
1026 i = hi = 0;
1027 do {
1028 /* Find the next free page. */
1029 lo = ffsl(~(((1UL << hi) - 1) | rv->popmap[i]));
1030 while (lo == 0 && ++i < NPOPMAP)
1031 lo = ffsl(~rv->popmap[i]);
1032 if (i == NPOPMAP)
1033 break;
1034 /* Convert from ffsl() to ordinary bit numbering. */
1035 lo--;
1036 next_free = NBPOPMAP * i + lo;
1037 pa = VM_PAGE_TO_PHYS(&rv->pages[next_free]);
1038 KASSERT(pa >= low,
1039 ("vm_reserv_reclaim_contig: pa is too low"));
1040 if (pa + size > high) {
1041 /* The rest of this reservation is too high. */
1042 break;
1043 } else if ((pa & (alignment - 1)) != 0 ||
1044 ((pa ^ (pa + size - 1)) & ~(boundary - 1)) != 0) {
1045 /*
1046 * The current page doesn't meet the alignment
1047 * and/or boundary requirements. Continue
1048 * searching this reservation until the rest
1049 * of its free pages are either excluded or
1050 * exhausted.
1051 */
1052 hi = lo + 1;
1053 if (hi >= NBPOPMAP) {
1054 hi = 0;
1055 i++;
1056 }
1057 continue;
1058 }
1059 /* Find the next used page. */
1060 hi = ffsl(rv->popmap[i] & ~((1UL << lo) - 1));
1061 while (hi == 0 && ++i < NPOPMAP) {
1062 if ((NBPOPMAP * i - next_free) * PAGE_SIZE >=
1063 size) {
1064 vm_reserv_reclaim(rv);
1065 return (TRUE);
1066 }
1067 hi = ffsl(rv->popmap[i]);
1068 }
1069 /* Convert from ffsl() to ordinary bit numbering. */
1070 if (i != NPOPMAP)
1071 hi--;
1072 if ((NBPOPMAP * i + hi - next_free) * PAGE_SIZE >=
1073 size) {
1074 vm_reserv_reclaim(rv);
1075 return (TRUE);
1076 }
1077 } while (i < NPOPMAP);
1078 }
1079 return (FALSE);
1080 }
1081
1082 /*
1083 * Transfers the reservation underlying the given page to a new object.
1084 *
1085 * The object must be locked.
1086 */
1087 void
1088 vm_reserv_rename(vm_page_t m, vm_object_t new_object, vm_object_t old_object,
1089 vm_pindex_t old_object_offset)
1090 {
1091 vm_reserv_t rv;
1092
1093 VM_OBJECT_ASSERT_WLOCKED(new_object);
1094 rv = vm_reserv_from_page(m);
1095 if (rv->object == old_object) {
1096 mtx_lock(&vm_page_queue_free_mtx);
1097 if (rv->object == old_object) {
1098 LIST_REMOVE(rv, objq);
1099 LIST_INSERT_HEAD(&new_object->rvq, rv, objq);
1100 rv->object = new_object;
1101 rv->pindex -= old_object_offset;
1102 }
1103 mtx_unlock(&vm_page_queue_free_mtx);
1104 }
1105 }
1106
1107 /*
1108 * Returns the size (in bytes) of a reservation of the specified level.
1109 */
1110 int
1111 vm_reserv_size(int level)
1112 {
1113
1114 switch (level) {
1115 case 0:
1116 return (VM_LEVEL_0_SIZE);
1117 case -1:
1118 return (PAGE_SIZE);
1119 default:
1120 return (0);
1121 }
1122 }
1123
1124 /*
1125 * Allocates the virtual and physical memory required by the reservation
1126 * management system's data structures, in particular, the reservation array.
1127 */
1128 vm_paddr_t
1129 vm_reserv_startup(vm_offset_t *vaddr, vm_paddr_t end, vm_paddr_t high_water)
1130 {
1131 vm_paddr_t new_end;
1132 size_t size;
1133
1134 /*
1135 * Calculate the size (in bytes) of the reservation array. Round up
1136 * from "high_water" because every small page is mapped to an element
1137 * in the reservation array based on its physical address. Thus, the
1138 * number of elements in the reservation array can be greater than the
1139 * number of superpages.
1140 */
1141 size = howmany(high_water, VM_LEVEL_0_SIZE) * sizeof(struct vm_reserv);
1142
1143 /*
1144 * Allocate and map the physical memory for the reservation array. The
1145 * next available virtual address is returned by reference.
1146 */
1147 new_end = end - round_page(size);
1148 vm_reserv_array = (void *)(uintptr_t)pmap_map(vaddr, new_end, end,
1149 VM_PROT_READ | VM_PROT_WRITE);
1150 bzero(vm_reserv_array, size);
1151
1152 /*
1153 * Return the next available physical address.
1154 */
1155 return (new_end);
1156 }
1157
1158 #endif /* VM_NRESERVLEVEL > 0 */
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