FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_pageout.c
1 /*-
2 * Copyright (c) 1991 Regents of the University of California.
3 * All rights reserved.
4 * Copyright (c) 1994 John S. Dyson
5 * All rights reserved.
6 * Copyright (c) 1994 David Greenman
7 * All rights reserved.
8 * Copyright (c) 2005 Yahoo! Technologies Norway AS
9 * All rights reserved.
10 *
11 * This code is derived from software contributed to Berkeley by
12 * The Mach Operating System project at Carnegie-Mellon University.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
22 * 3. All advertising materials mentioning features or use of this software
23 * must display the following acknowledgement:
24 * This product includes software developed by the University of
25 * California, Berkeley and its contributors.
26 * 4. Neither the name of the University nor the names of its contributors
27 * may be used to endorse or promote products derived from this software
28 * without specific prior written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 * SUCH DAMAGE.
41 *
42 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
43 *
44 *
45 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
46 * All rights reserved.
47 *
48 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
49 *
50 * Permission to use, copy, modify and distribute this software and
51 * its documentation is hereby granted, provided that both the copyright
52 * notice and this permission notice appear in all copies of the
53 * software, derivative works or modified versions, and any portions
54 * thereof, and that both notices appear in supporting documentation.
55 *
56 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
57 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
58 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
59 *
60 * Carnegie Mellon requests users of this software to return to
61 *
62 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
63 * School of Computer Science
64 * Carnegie Mellon University
65 * Pittsburgh PA 15213-3890
66 *
67 * any improvements or extensions that they make and grant Carnegie the
68 * rights to redistribute these changes.
69 */
70
71 /*
72 * The proverbial page-out daemon.
73 */
74
75 #include <sys/cdefs.h>
76 __FBSDID("$FreeBSD$");
77
78 #include "opt_vm.h"
79 #include <sys/param.h>
80 #include <sys/systm.h>
81 #include <sys/kernel.h>
82 #include <sys/eventhandler.h>
83 #include <sys/lock.h>
84 #include <sys/mutex.h>
85 #include <sys/proc.h>
86 #include <sys/kthread.h>
87 #include <sys/ktr.h>
88 #include <sys/mount.h>
89 #include <sys/resourcevar.h>
90 #include <sys/sched.h>
91 #include <sys/signalvar.h>
92 #include <sys/vnode.h>
93 #include <sys/vmmeter.h>
94 #include <sys/sx.h>
95 #include <sys/sysctl.h>
96
97 #include <vm/vm.h>
98 #include <vm/vm_param.h>
99 #include <vm/vm_object.h>
100 #include <vm/vm_page.h>
101 #include <vm/vm_map.h>
102 #include <vm/vm_pageout.h>
103 #include <vm/vm_pager.h>
104 #include <vm/swap_pager.h>
105 #include <vm/vm_extern.h>
106 #include <vm/uma.h>
107
108 #include <machine/mutex.h>
109
110 /*
111 * System initialization
112 */
113
114 /* the kernel process "vm_pageout"*/
115 static void vm_pageout(void);
116 static int vm_pageout_clean(vm_page_t);
117 static void vm_pageout_scan(int pass);
118
119 struct proc *pageproc;
120
121 static struct kproc_desc page_kp = {
122 "pagedaemon",
123 vm_pageout,
124 &pageproc
125 };
126 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start,
127 &page_kp);
128
129 #if !defined(NO_SWAPPING)
130 /* the kernel process "vm_daemon"*/
131 static void vm_daemon(void);
132 static struct proc *vmproc;
133
134 static struct kproc_desc vm_kp = {
135 "vmdaemon",
136 vm_daemon,
137 &vmproc
138 };
139 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp);
140 #endif
141
142
143 int vm_pages_needed; /* Event on which pageout daemon sleeps */
144 int vm_pageout_deficit; /* Estimated number of pages deficit */
145 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */
146
147 #if !defined(NO_SWAPPING)
148 static int vm_pageout_req_swapout; /* XXX */
149 static int vm_daemon_needed;
150 static struct mtx vm_daemon_mtx;
151 /* Allow for use by vm_pageout before vm_daemon is initialized. */
152 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF);
153 #endif
154 static int vm_max_launder = 32;
155 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0;
156 static int vm_pageout_full_stats_interval = 0;
157 static int vm_pageout_algorithm=0;
158 static int defer_swap_pageouts=0;
159 static int disable_swap_pageouts=0;
160
161 #if defined(NO_SWAPPING)
162 static int vm_swap_enabled=0;
163 static int vm_swap_idle_enabled=0;
164 #else
165 static int vm_swap_enabled=1;
166 static int vm_swap_idle_enabled=0;
167 #endif
168
169 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm,
170 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt");
171
172 SYSCTL_INT(_vm, OID_AUTO, max_launder,
173 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout");
174
175 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max,
176 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length");
177
178 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval,
179 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan");
180
181 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval,
182 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan");
183
184 #if defined(NO_SWAPPING)
185 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
186 CTLFLAG_RD, &vm_swap_enabled, 0, "");
187 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
188 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "");
189 #else
190 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
191 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout");
192 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
193 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
194 #endif
195
196 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts,
197 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem");
198
199 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts,
200 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages");
201
202 static int pageout_lock_miss;
203 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss,
204 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout");
205
206 #define VM_PAGEOUT_PAGE_COUNT 16
207 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
208
209 int vm_page_max_wired; /* XXX max # of wired pages system-wide */
210 SYSCTL_INT(_vm, OID_AUTO, max_wired,
211 CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count");
212
213 #if !defined(NO_SWAPPING)
214 static void vm_pageout_map_deactivate_pages(vm_map_t, long);
215 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long);
216 static void vm_req_vmdaemon(int req);
217 #endif
218 static void vm_pageout_page_stats(void);
219
220 /*
221 * vm_pageout_fallback_object_lock:
222 *
223 * Lock vm object currently associated with `m'. VM_OBJECT_TRYLOCK is
224 * known to have failed and page queue must be either PQ_ACTIVE or
225 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues
226 * while locking the vm object. Use marker page to detect page queue
227 * changes and maintain notion of next page on page queue. Return
228 * TRUE if no changes were detected, FALSE otherwise. vm object is
229 * locked on return.
230 *
231 * This function depends on both the lock portion of struct vm_object
232 * and normal struct vm_page being type stable.
233 */
234 boolean_t
235 vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next)
236 {
237 struct vm_page marker;
238 boolean_t unchanged;
239 u_short queue;
240 vm_object_t object;
241
242 /*
243 * Initialize our marker
244 */
245 bzero(&marker, sizeof(marker));
246 marker.flags = PG_FICTITIOUS | PG_MARKER;
247 marker.oflags = VPO_BUSY;
248 marker.queue = m->queue;
249 marker.wire_count = 1;
250
251 queue = m->queue;
252 object = m->object;
253
254 TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl,
255 m, &marker, pageq);
256 vm_page_unlock_queues();
257 VM_OBJECT_LOCK(object);
258 vm_page_lock_queues();
259
260 /* Page queue might have changed. */
261 *next = TAILQ_NEXT(&marker, pageq);
262 unchanged = (m->queue == queue &&
263 m->object == object &&
264 &marker == TAILQ_NEXT(m, pageq));
265 TAILQ_REMOVE(&vm_page_queues[queue].pl,
266 &marker, pageq);
267 return (unchanged);
268 }
269
270 /*
271 * vm_pageout_clean:
272 *
273 * Clean the page and remove it from the laundry.
274 *
275 * We set the busy bit to cause potential page faults on this page to
276 * block. Note the careful timing, however, the busy bit isn't set till
277 * late and we cannot do anything that will mess with the page.
278 */
279 static int
280 vm_pageout_clean(m)
281 vm_page_t m;
282 {
283 vm_object_t object;
284 vm_page_t mc[2*vm_pageout_page_count];
285 int pageout_count;
286 int ib, is, page_base;
287 vm_pindex_t pindex = m->pindex;
288
289 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
290 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
291
292 /*
293 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP
294 * with the new swapper, but we could have serious problems paging
295 * out other object types if there is insufficient memory.
296 *
297 * Unfortunately, checking free memory here is far too late, so the
298 * check has been moved up a procedural level.
299 */
300
301 /*
302 * Can't clean the page if it's busy or held.
303 */
304 if ((m->hold_count != 0) ||
305 ((m->busy != 0) || (m->oflags & VPO_BUSY))) {
306 return 0;
307 }
308
309 mc[vm_pageout_page_count] = m;
310 pageout_count = 1;
311 page_base = vm_pageout_page_count;
312 ib = 1;
313 is = 1;
314
315 /*
316 * Scan object for clusterable pages.
317 *
318 * We can cluster ONLY if: ->> the page is NOT
319 * clean, wired, busy, held, or mapped into a
320 * buffer, and one of the following:
321 * 1) The page is inactive, or a seldom used
322 * active page.
323 * -or-
324 * 2) we force the issue.
325 *
326 * During heavy mmap/modification loads the pageout
327 * daemon can really fragment the underlying file
328 * due to flushing pages out of order and not trying
329 * align the clusters (which leave sporatic out-of-order
330 * holes). To solve this problem we do the reverse scan
331 * first and attempt to align our cluster, then do a
332 * forward scan if room remains.
333 */
334 object = m->object;
335 more:
336 while (ib && pageout_count < vm_pageout_page_count) {
337 vm_page_t p;
338
339 if (ib > pindex) {
340 ib = 0;
341 break;
342 }
343
344 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) {
345 ib = 0;
346 break;
347 }
348 if ((p->oflags & VPO_BUSY) || p->busy) {
349 ib = 0;
350 break;
351 }
352 vm_page_test_dirty(p);
353 if ((p->dirty & p->valid) == 0 ||
354 p->queue != PQ_INACTIVE ||
355 p->wire_count != 0 || /* may be held by buf cache */
356 p->hold_count != 0) { /* may be undergoing I/O */
357 ib = 0;
358 break;
359 }
360 mc[--page_base] = p;
361 ++pageout_count;
362 ++ib;
363 /*
364 * alignment boundry, stop here and switch directions. Do
365 * not clear ib.
366 */
367 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0)
368 break;
369 }
370
371 while (pageout_count < vm_pageout_page_count &&
372 pindex + is < object->size) {
373 vm_page_t p;
374
375 if ((p = vm_page_lookup(object, pindex + is)) == NULL)
376 break;
377 if ((p->oflags & VPO_BUSY) || p->busy) {
378 break;
379 }
380 vm_page_test_dirty(p);
381 if ((p->dirty & p->valid) == 0 ||
382 p->queue != PQ_INACTIVE ||
383 p->wire_count != 0 || /* may be held by buf cache */
384 p->hold_count != 0) { /* may be undergoing I/O */
385 break;
386 }
387 mc[page_base + pageout_count] = p;
388 ++pageout_count;
389 ++is;
390 }
391
392 /*
393 * If we exhausted our forward scan, continue with the reverse scan
394 * when possible, even past a page boundry. This catches boundry
395 * conditions.
396 */
397 if (ib && pageout_count < vm_pageout_page_count)
398 goto more;
399
400 /*
401 * we allow reads during pageouts...
402 */
403 return (vm_pageout_flush(&mc[page_base], pageout_count, 0));
404 }
405
406 /*
407 * vm_pageout_flush() - launder the given pages
408 *
409 * The given pages are laundered. Note that we setup for the start of
410 * I/O ( i.e. busy the page ), mark it read-only, and bump the object
411 * reference count all in here rather then in the parent. If we want
412 * the parent to do more sophisticated things we may have to change
413 * the ordering.
414 */
415 int
416 vm_pageout_flush(vm_page_t *mc, int count, int flags)
417 {
418 vm_object_t object = mc[0]->object;
419 int pageout_status[count];
420 int numpagedout = 0;
421 int i;
422
423 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
424 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
425 /*
426 * Initiate I/O. Bump the vm_page_t->busy counter and
427 * mark the pages read-only.
428 *
429 * We do not have to fixup the clean/dirty bits here... we can
430 * allow the pager to do it after the I/O completes.
431 *
432 * NOTE! mc[i]->dirty may be partial or fragmented due to an
433 * edge case with file fragments.
434 */
435 for (i = 0; i < count; i++) {
436 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL,
437 ("vm_pageout_flush: partially invalid page %p index %d/%d",
438 mc[i], i, count));
439 vm_page_io_start(mc[i]);
440 pmap_remove_write(mc[i]);
441 }
442 vm_page_unlock_queues();
443 vm_object_pip_add(object, count);
444
445 vm_pager_put_pages(object, mc, count, flags, pageout_status);
446
447 vm_page_lock_queues();
448 for (i = 0; i < count; i++) {
449 vm_page_t mt = mc[i];
450
451 KASSERT(pageout_status[i] == VM_PAGER_PEND ||
452 (mt->flags & PG_WRITEABLE) == 0,
453 ("vm_pageout_flush: page %p is not write protected", mt));
454 switch (pageout_status[i]) {
455 case VM_PAGER_OK:
456 case VM_PAGER_PEND:
457 numpagedout++;
458 break;
459 case VM_PAGER_BAD:
460 /*
461 * Page outside of range of object. Right now we
462 * essentially lose the changes by pretending it
463 * worked.
464 */
465 pmap_clear_modify(mt);
466 vm_page_undirty(mt);
467 break;
468 case VM_PAGER_ERROR:
469 case VM_PAGER_FAIL:
470 /*
471 * If page couldn't be paged out, then reactivate the
472 * page so it doesn't clog the inactive list. (We
473 * will try paging out it again later).
474 */
475 vm_page_activate(mt);
476 break;
477 case VM_PAGER_AGAIN:
478 break;
479 }
480
481 /*
482 * If the operation is still going, leave the page busy to
483 * block all other accesses. Also, leave the paging in
484 * progress indicator set so that we don't attempt an object
485 * collapse.
486 */
487 if (pageout_status[i] != VM_PAGER_PEND) {
488 vm_object_pip_wakeup(object);
489 vm_page_io_finish(mt);
490 if (vm_page_count_severe())
491 vm_page_try_to_cache(mt);
492 }
493 }
494 return numpagedout;
495 }
496
497 #if !defined(NO_SWAPPING)
498 /*
499 * vm_pageout_object_deactivate_pages
500 *
501 * deactivate enough pages to satisfy the inactive target
502 * requirements or if vm_page_proc_limit is set, then
503 * deactivate all of the pages in the object and its
504 * backing_objects.
505 *
506 * The object and map must be locked.
507 */
508 static void
509 vm_pageout_object_deactivate_pages(pmap, first_object, desired)
510 pmap_t pmap;
511 vm_object_t first_object;
512 long desired;
513 {
514 vm_object_t backing_object, object;
515 vm_page_t p, next;
516 int actcount, rcount, remove_mode;
517
518 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED);
519 if (first_object->type == OBJT_DEVICE || first_object->type == OBJT_PHYS)
520 return;
521 for (object = first_object;; object = backing_object) {
522 if (pmap_resident_count(pmap) <= desired)
523 goto unlock_return;
524 if (object->paging_in_progress)
525 goto unlock_return;
526
527 remove_mode = 0;
528 if (object->shadow_count > 1)
529 remove_mode = 1;
530 /*
531 * scan the objects entire memory queue
532 */
533 rcount = object->resident_page_count;
534 p = TAILQ_FIRST(&object->memq);
535 vm_page_lock_queues();
536 while (p && (rcount-- > 0)) {
537 if (pmap_resident_count(pmap) <= desired) {
538 vm_page_unlock_queues();
539 goto unlock_return;
540 }
541 next = TAILQ_NEXT(p, listq);
542 cnt.v_pdpages++;
543 if (p->wire_count != 0 ||
544 p->hold_count != 0 ||
545 p->busy != 0 ||
546 (p->oflags & VPO_BUSY) ||
547 (p->flags & PG_UNMANAGED) ||
548 !pmap_page_exists_quick(pmap, p)) {
549 p = next;
550 continue;
551 }
552 actcount = pmap_ts_referenced(p);
553 if (actcount) {
554 vm_page_flag_set(p, PG_REFERENCED);
555 } else if (p->flags & PG_REFERENCED) {
556 actcount = 1;
557 }
558 if ((p->queue != PQ_ACTIVE) &&
559 (p->flags & PG_REFERENCED)) {
560 vm_page_activate(p);
561 p->act_count += actcount;
562 vm_page_flag_clear(p, PG_REFERENCED);
563 } else if (p->queue == PQ_ACTIVE) {
564 if ((p->flags & PG_REFERENCED) == 0) {
565 p->act_count -= min(p->act_count, ACT_DECLINE);
566 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) {
567 pmap_remove_all(p);
568 vm_page_deactivate(p);
569 } else {
570 vm_pageq_requeue(p);
571 }
572 } else {
573 vm_page_activate(p);
574 vm_page_flag_clear(p, PG_REFERENCED);
575 if (p->act_count < (ACT_MAX - ACT_ADVANCE))
576 p->act_count += ACT_ADVANCE;
577 vm_pageq_requeue(p);
578 }
579 } else if (p->queue == PQ_INACTIVE) {
580 pmap_remove_all(p);
581 }
582 p = next;
583 }
584 vm_page_unlock_queues();
585 if ((backing_object = object->backing_object) == NULL)
586 goto unlock_return;
587 VM_OBJECT_LOCK(backing_object);
588 if (object != first_object)
589 VM_OBJECT_UNLOCK(object);
590 }
591 unlock_return:
592 if (object != first_object)
593 VM_OBJECT_UNLOCK(object);
594 }
595
596 /*
597 * deactivate some number of pages in a map, try to do it fairly, but
598 * that is really hard to do.
599 */
600 static void
601 vm_pageout_map_deactivate_pages(map, desired)
602 vm_map_t map;
603 long desired;
604 {
605 vm_map_entry_t tmpe;
606 vm_object_t obj, bigobj;
607 int nothingwired;
608
609 if (!vm_map_trylock(map))
610 return;
611
612 bigobj = NULL;
613 nothingwired = TRUE;
614
615 /*
616 * first, search out the biggest object, and try to free pages from
617 * that.
618 */
619 tmpe = map->header.next;
620 while (tmpe != &map->header) {
621 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
622 obj = tmpe->object.vm_object;
623 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) {
624 if (obj->shadow_count <= 1 &&
625 (bigobj == NULL ||
626 bigobj->resident_page_count < obj->resident_page_count)) {
627 if (bigobj != NULL)
628 VM_OBJECT_UNLOCK(bigobj);
629 bigobj = obj;
630 } else
631 VM_OBJECT_UNLOCK(obj);
632 }
633 }
634 if (tmpe->wired_count > 0)
635 nothingwired = FALSE;
636 tmpe = tmpe->next;
637 }
638
639 if (bigobj != NULL) {
640 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired);
641 VM_OBJECT_UNLOCK(bigobj);
642 }
643 /*
644 * Next, hunt around for other pages to deactivate. We actually
645 * do this search sort of wrong -- .text first is not the best idea.
646 */
647 tmpe = map->header.next;
648 while (tmpe != &map->header) {
649 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
650 break;
651 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
652 obj = tmpe->object.vm_object;
653 if (obj != NULL) {
654 VM_OBJECT_LOCK(obj);
655 vm_pageout_object_deactivate_pages(map->pmap, obj, desired);
656 VM_OBJECT_UNLOCK(obj);
657 }
658 }
659 tmpe = tmpe->next;
660 }
661
662 /*
663 * Remove all mappings if a process is swapped out, this will free page
664 * table pages.
665 */
666 if (desired == 0 && nothingwired) {
667 pmap_remove(vm_map_pmap(map), vm_map_min(map),
668 vm_map_max(map));
669 }
670 vm_map_unlock(map);
671 }
672 #endif /* !defined(NO_SWAPPING) */
673
674 /*
675 * vm_pageout_scan does the dirty work for the pageout daemon.
676 */
677 static void
678 vm_pageout_scan(int pass)
679 {
680 vm_page_t m, next;
681 struct vm_page marker;
682 int page_shortage, maxscan, pcount;
683 int addl_page_shortage, addl_page_shortage_init;
684 struct proc *p, *bigproc;
685 struct thread *td;
686 vm_offset_t size, bigsize;
687 vm_object_t object;
688 int actcount;
689 int vnodes_skipped = 0;
690 int maxlaunder;
691
692 /*
693 * Decrease registered cache sizes.
694 */
695 EVENTHANDLER_INVOKE(vm_lowmem, 0);
696 /*
697 * We do this explicitly after the caches have been drained above.
698 */
699 uma_reclaim();
700
701 addl_page_shortage_init = atomic_readandclear_int(&vm_pageout_deficit);
702
703 /*
704 * Calculate the number of pages we want to either free or move
705 * to the cache.
706 */
707 page_shortage = vm_paging_target() + addl_page_shortage_init;
708
709 /*
710 * Initialize our marker
711 */
712 bzero(&marker, sizeof(marker));
713 marker.flags = PG_FICTITIOUS | PG_MARKER;
714 marker.oflags = VPO_BUSY;
715 marker.queue = PQ_INACTIVE;
716 marker.wire_count = 1;
717
718 /*
719 * Start scanning the inactive queue for pages we can move to the
720 * cache or free. The scan will stop when the target is reached or
721 * we have scanned the entire inactive queue. Note that m->act_count
722 * is not used to form decisions for the inactive queue, only for the
723 * active queue.
724 *
725 * maxlaunder limits the number of dirty pages we flush per scan.
726 * For most systems a smaller value (16 or 32) is more robust under
727 * extreme memory and disk pressure because any unnecessary writes
728 * to disk can result in extreme performance degredation. However,
729 * systems with excessive dirty pages (especially when MAP_NOSYNC is
730 * used) will die horribly with limited laundering. If the pageout
731 * daemon cannot clean enough pages in the first pass, we let it go
732 * all out in succeeding passes.
733 */
734 if ((maxlaunder = vm_max_launder) <= 1)
735 maxlaunder = 1;
736 if (pass)
737 maxlaunder = 10000;
738 vm_page_lock_queues();
739 rescan0:
740 addl_page_shortage = addl_page_shortage_init;
741 maxscan = cnt.v_inactive_count;
742
743 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl);
744 m != NULL && maxscan-- > 0 && page_shortage > 0;
745 m = next) {
746
747 cnt.v_pdpages++;
748
749 if (VM_PAGE_GETQUEUE(m) != PQ_INACTIVE) {
750 goto rescan0;
751 }
752
753 next = TAILQ_NEXT(m, pageq);
754 object = m->object;
755
756 /*
757 * skip marker pages
758 */
759 if (m->flags & PG_MARKER)
760 continue;
761
762 /*
763 * A held page may be undergoing I/O, so skip it.
764 */
765 if (m->hold_count) {
766 vm_pageq_requeue(m);
767 addl_page_shortage++;
768 continue;
769 }
770 /*
771 * Don't mess with busy pages, keep in the front of the
772 * queue, most likely are being paged out.
773 */
774 if (!VM_OBJECT_TRYLOCK(object) &&
775 (!vm_pageout_fallback_object_lock(m, &next) ||
776 m->hold_count != 0)) {
777 VM_OBJECT_UNLOCK(object);
778 addl_page_shortage++;
779 continue;
780 }
781 if (m->busy || (m->oflags & VPO_BUSY)) {
782 VM_OBJECT_UNLOCK(object);
783 addl_page_shortage++;
784 continue;
785 }
786
787 /*
788 * If the object is not being used, we ignore previous
789 * references.
790 */
791 if (object->ref_count == 0) {
792 vm_page_flag_clear(m, PG_REFERENCED);
793 pmap_clear_reference(m);
794
795 /*
796 * Otherwise, if the page has been referenced while in the
797 * inactive queue, we bump the "activation count" upwards,
798 * making it less likely that the page will be added back to
799 * the inactive queue prematurely again. Here we check the
800 * page tables (or emulated bits, if any), given the upper
801 * level VM system not knowing anything about existing
802 * references.
803 */
804 } else if (((m->flags & PG_REFERENCED) == 0) &&
805 (actcount = pmap_ts_referenced(m))) {
806 vm_page_activate(m);
807 VM_OBJECT_UNLOCK(object);
808 m->act_count += (actcount + ACT_ADVANCE);
809 continue;
810 }
811
812 /*
813 * If the upper level VM system knows about any page
814 * references, we activate the page. We also set the
815 * "activation count" higher than normal so that we will less
816 * likely place pages back onto the inactive queue again.
817 */
818 if ((m->flags & PG_REFERENCED) != 0) {
819 vm_page_flag_clear(m, PG_REFERENCED);
820 actcount = pmap_ts_referenced(m);
821 vm_page_activate(m);
822 VM_OBJECT_UNLOCK(object);
823 m->act_count += (actcount + ACT_ADVANCE + 1);
824 continue;
825 }
826
827 /*
828 * If the upper level VM system doesn't know anything about
829 * the page being dirty, we have to check for it again. As
830 * far as the VM code knows, any partially dirty pages are
831 * fully dirty.
832 */
833 if (m->dirty == 0 && !pmap_is_modified(m)) {
834 /*
835 * Avoid a race condition: Unless write access is
836 * removed from the page, another processor could
837 * modify it before all access is removed by the call
838 * to vm_page_cache() below. If vm_page_cache() finds
839 * that the page has been modified when it removes all
840 * access, it panics because it cannot cache dirty
841 * pages. In principle, we could eliminate just write
842 * access here rather than all access. In the expected
843 * case, when there are no last instant modifications
844 * to the page, removing all access will be cheaper
845 * overall.
846 */
847 if ((m->flags & PG_WRITEABLE) != 0)
848 pmap_remove_all(m);
849 } else {
850 vm_page_dirty(m);
851 }
852
853 if (m->valid == 0) {
854 /*
855 * Invalid pages can be easily freed
856 */
857 vm_page_free(m);
858 cnt.v_dfree++;
859 --page_shortage;
860 } else if (m->dirty == 0) {
861 /*
862 * Clean pages can be placed onto the cache queue.
863 * This effectively frees them.
864 */
865 vm_page_cache(m);
866 --page_shortage;
867 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) {
868 /*
869 * Dirty pages need to be paged out, but flushing
870 * a page is extremely expensive verses freeing
871 * a clean page. Rather then artificially limiting
872 * the number of pages we can flush, we instead give
873 * dirty pages extra priority on the inactive queue
874 * by forcing them to be cycled through the queue
875 * twice before being flushed, after which the
876 * (now clean) page will cycle through once more
877 * before being freed. This significantly extends
878 * the thrash point for a heavily loaded machine.
879 */
880 vm_page_flag_set(m, PG_WINATCFLS);
881 vm_pageq_requeue(m);
882 } else if (maxlaunder > 0) {
883 /*
884 * We always want to try to flush some dirty pages if
885 * we encounter them, to keep the system stable.
886 * Normally this number is small, but under extreme
887 * pressure where there are insufficient clean pages
888 * on the inactive queue, we may have to go all out.
889 */
890 int swap_pageouts_ok, vfslocked = 0;
891 struct vnode *vp = NULL;
892 struct mount *mp = NULL;
893
894 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) {
895 swap_pageouts_ok = 1;
896 } else {
897 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts);
898 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts &&
899 vm_page_count_min());
900
901 }
902
903 /*
904 * We don't bother paging objects that are "dead".
905 * Those objects are in a "rundown" state.
906 */
907 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
908 VM_OBJECT_UNLOCK(object);
909 vm_pageq_requeue(m);
910 continue;
911 }
912
913 /*
914 * Following operations may unlock
915 * vm_page_queue_mtx, invalidating the 'next'
916 * pointer. To prevent an inordinate number
917 * of restarts we use our marker to remember
918 * our place.
919 *
920 */
921 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl,
922 m, &marker, pageq);
923 /*
924 * The object is already known NOT to be dead. It
925 * is possible for the vget() to block the whole
926 * pageout daemon, but the new low-memory handling
927 * code should prevent it.
928 *
929 * The previous code skipped locked vnodes and, worse,
930 * reordered pages in the queue. This results in
931 * completely non-deterministic operation and, on a
932 * busy system, can lead to extremely non-optimal
933 * pageouts. For example, it can cause clean pages
934 * to be freed and dirty pages to be moved to the end
935 * of the queue. Since dirty pages are also moved to
936 * the end of the queue once-cleaned, this gives
937 * way too large a weighting to defering the freeing
938 * of dirty pages.
939 *
940 * We can't wait forever for the vnode lock, we might
941 * deadlock due to a vn_read() getting stuck in
942 * vm_wait while holding this vnode. We skip the
943 * vnode if we can't get it in a reasonable amount
944 * of time.
945 */
946 if (object->type == OBJT_VNODE) {
947 vp = object->handle;
948 if (vp->v_type == VREG &&
949 vn_start_write(vp, &mp, V_NOWAIT) != 0) {
950 mp = NULL;
951 ++pageout_lock_miss;
952 if (object->flags & OBJ_MIGHTBEDIRTY)
953 vnodes_skipped++;
954 goto unlock_and_continue;
955 }
956 vm_page_unlock_queues();
957 vm_object_reference_locked(object);
958 VM_OBJECT_UNLOCK(object);
959 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
960 if (vget(vp, LK_EXCLUSIVE | LK_TIMELOCK,
961 curthread)) {
962 VM_OBJECT_LOCK(object);
963 vm_page_lock_queues();
964 ++pageout_lock_miss;
965 if (object->flags & OBJ_MIGHTBEDIRTY)
966 vnodes_skipped++;
967 vp = NULL;
968 goto unlock_and_continue;
969 }
970 VM_OBJECT_LOCK(object);
971 vm_page_lock_queues();
972 /*
973 * The page might have been moved to another
974 * queue during potential blocking in vget()
975 * above. The page might have been freed and
976 * reused for another vnode.
977 */
978 if (VM_PAGE_GETQUEUE(m) != PQ_INACTIVE ||
979 m->object != object ||
980 TAILQ_NEXT(m, pageq) != &marker) {
981 if (object->flags & OBJ_MIGHTBEDIRTY)
982 vnodes_skipped++;
983 goto unlock_and_continue;
984 }
985
986 /*
987 * The page may have been busied during the
988 * blocking in vget(). We don't move the
989 * page back onto the end of the queue so that
990 * statistics are more correct if we don't.
991 */
992 if (m->busy || (m->oflags & VPO_BUSY)) {
993 goto unlock_and_continue;
994 }
995
996 /*
997 * If the page has become held it might
998 * be undergoing I/O, so skip it
999 */
1000 if (m->hold_count) {
1001 vm_pageq_requeue(m);
1002 if (object->flags & OBJ_MIGHTBEDIRTY)
1003 vnodes_skipped++;
1004 goto unlock_and_continue;
1005 }
1006 }
1007
1008 /*
1009 * If a page is dirty, then it is either being washed
1010 * (but not yet cleaned) or it is still in the
1011 * laundry. If it is still in the laundry, then we
1012 * start the cleaning operation.
1013 *
1014 * decrement page_shortage on success to account for
1015 * the (future) cleaned page. Otherwise we could wind
1016 * up laundering or cleaning too many pages.
1017 */
1018 if (vm_pageout_clean(m) != 0) {
1019 --page_shortage;
1020 --maxlaunder;
1021 }
1022 unlock_and_continue:
1023 VM_OBJECT_UNLOCK(object);
1024 if (mp != NULL) {
1025 vm_page_unlock_queues();
1026 if (vp != NULL)
1027 vput(vp);
1028 VFS_UNLOCK_GIANT(vfslocked);
1029 vm_object_deallocate(object);
1030 vn_finished_write(mp);
1031 vm_page_lock_queues();
1032 }
1033 next = TAILQ_NEXT(&marker, pageq);
1034 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl,
1035 &marker, pageq);
1036 continue;
1037 }
1038 VM_OBJECT_UNLOCK(object);
1039 }
1040
1041 /*
1042 * Compute the number of pages we want to try to move from the
1043 * active queue to the inactive queue.
1044 */
1045 page_shortage = vm_paging_target() +
1046 cnt.v_inactive_target - cnt.v_inactive_count;
1047 page_shortage += addl_page_shortage;
1048
1049 /*
1050 * Scan the active queue for things we can deactivate. We nominally
1051 * track the per-page activity counter and use it to locate
1052 * deactivation candidates.
1053 */
1054 pcount = cnt.v_active_count;
1055 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1056
1057 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) {
1058
1059 KASSERT(VM_PAGE_INQUEUE2(m, PQ_ACTIVE),
1060 ("vm_pageout_scan: page %p isn't active", m));
1061
1062 next = TAILQ_NEXT(m, pageq);
1063 object = m->object;
1064 if ((m->flags & PG_MARKER) != 0) {
1065 m = next;
1066 continue;
1067 }
1068 if (!VM_OBJECT_TRYLOCK(object) &&
1069 !vm_pageout_fallback_object_lock(m, &next)) {
1070 VM_OBJECT_UNLOCK(object);
1071 m = next;
1072 continue;
1073 }
1074
1075 /*
1076 * Don't deactivate pages that are busy.
1077 */
1078 if ((m->busy != 0) ||
1079 (m->oflags & VPO_BUSY) ||
1080 (m->hold_count != 0)) {
1081 VM_OBJECT_UNLOCK(object);
1082 vm_pageq_requeue(m);
1083 m = next;
1084 continue;
1085 }
1086
1087 /*
1088 * The count for pagedaemon pages is done after checking the
1089 * page for eligibility...
1090 */
1091 cnt.v_pdpages++;
1092
1093 /*
1094 * Check to see "how much" the page has been used.
1095 */
1096 actcount = 0;
1097 if (object->ref_count != 0) {
1098 if (m->flags & PG_REFERENCED) {
1099 actcount += 1;
1100 }
1101 actcount += pmap_ts_referenced(m);
1102 if (actcount) {
1103 m->act_count += ACT_ADVANCE + actcount;
1104 if (m->act_count > ACT_MAX)
1105 m->act_count = ACT_MAX;
1106 }
1107 }
1108
1109 /*
1110 * Since we have "tested" this bit, we need to clear it now.
1111 */
1112 vm_page_flag_clear(m, PG_REFERENCED);
1113
1114 /*
1115 * Only if an object is currently being used, do we use the
1116 * page activation count stats.
1117 */
1118 if (actcount && (object->ref_count != 0)) {
1119 vm_pageq_requeue(m);
1120 } else {
1121 m->act_count -= min(m->act_count, ACT_DECLINE);
1122 if (vm_pageout_algorithm ||
1123 object->ref_count == 0 ||
1124 m->act_count == 0) {
1125 page_shortage--;
1126 if (object->ref_count == 0) {
1127 pmap_remove_all(m);
1128 if (m->dirty == 0)
1129 vm_page_cache(m);
1130 else
1131 vm_page_deactivate(m);
1132 } else {
1133 vm_page_deactivate(m);
1134 }
1135 } else {
1136 vm_pageq_requeue(m);
1137 }
1138 }
1139 VM_OBJECT_UNLOCK(object);
1140 m = next;
1141 }
1142 vm_page_unlock_queues();
1143 #if !defined(NO_SWAPPING)
1144 /*
1145 * Idle process swapout -- run once per second.
1146 */
1147 if (vm_swap_idle_enabled) {
1148 static long lsec;
1149 if (time_second != lsec) {
1150 vm_req_vmdaemon(VM_SWAP_IDLE);
1151 lsec = time_second;
1152 }
1153 }
1154 #endif
1155
1156 /*
1157 * If we didn't get enough free pages, and we have skipped a vnode
1158 * in a writeable object, wakeup the sync daemon. And kick swapout
1159 * if we did not get enough free pages.
1160 */
1161 if (vm_paging_target() > 0) {
1162 if (vnodes_skipped && vm_page_count_min())
1163 (void) speedup_syncer();
1164 #if !defined(NO_SWAPPING)
1165 if (vm_swap_enabled && vm_page_count_target())
1166 vm_req_vmdaemon(VM_SWAP_NORMAL);
1167 #endif
1168 }
1169
1170 /*
1171 * If we are critically low on one of RAM or swap and low on
1172 * the other, kill the largest process. However, we avoid
1173 * doing this on the first pass in order to give ourselves a
1174 * chance to flush out dirty vnode-backed pages and to allow
1175 * active pages to be moved to the inactive queue and reclaimed.
1176 *
1177 * We keep the process bigproc locked once we find it to keep anyone
1178 * from messing with it; however, there is a possibility of
1179 * deadlock if process B is bigproc and one of it's child processes
1180 * attempts to propagate a signal to B while we are waiting for A's
1181 * lock while walking this list. To avoid this, we don't block on
1182 * the process lock but just skip a process if it is already locked.
1183 */
1184 if (pass != 0 &&
1185 ((swap_pager_avail < 64 && vm_page_count_min()) ||
1186 (swap_pager_full && vm_paging_target() > 0))) {
1187 bigproc = NULL;
1188 bigsize = 0;
1189 sx_slock(&allproc_lock);
1190 FOREACH_PROC_IN_SYSTEM(p) {
1191 int breakout;
1192
1193 if (PROC_TRYLOCK(p) == 0)
1194 continue;
1195 /*
1196 * If this is a system or protected process, skip it.
1197 */
1198 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) ||
1199 (p->p_flag & P_PROTECTED) ||
1200 ((p->p_pid < 48) && (swap_pager_avail != 0))) {
1201 PROC_UNLOCK(p);
1202 continue;
1203 }
1204 /*
1205 * If the process is in a non-running type state,
1206 * don't touch it. Check all the threads individually.
1207 */
1208 PROC_SLOCK(p);
1209 breakout = 0;
1210 FOREACH_THREAD_IN_PROC(p, td) {
1211 thread_lock(td);
1212 if (!TD_ON_RUNQ(td) &&
1213 !TD_IS_RUNNING(td) &&
1214 !TD_IS_SLEEPING(td)) {
1215 thread_unlock(td);
1216 breakout = 1;
1217 break;
1218 }
1219 thread_unlock(td);
1220 }
1221 PROC_SUNLOCK(p);
1222 if (breakout) {
1223 PROC_UNLOCK(p);
1224 continue;
1225 }
1226 /*
1227 * get the process size
1228 */
1229 if (!vm_map_trylock_read(&p->p_vmspace->vm_map)) {
1230 PROC_UNLOCK(p);
1231 continue;
1232 }
1233 size = vmspace_swap_count(p->p_vmspace);
1234 vm_map_unlock_read(&p->p_vmspace->vm_map);
1235 size += vmspace_resident_count(p->p_vmspace);
1236 /*
1237 * if the this process is bigger than the biggest one
1238 * remember it.
1239 */
1240 if (size > bigsize) {
1241 if (bigproc != NULL)
1242 PROC_UNLOCK(bigproc);
1243 bigproc = p;
1244 bigsize = size;
1245 } else
1246 PROC_UNLOCK(p);
1247 }
1248 sx_sunlock(&allproc_lock);
1249 if (bigproc != NULL) {
1250 killproc(bigproc, "out of swap space");
1251 PROC_SLOCK(bigproc);
1252 sched_nice(bigproc, PRIO_MIN);
1253 PROC_SUNLOCK(bigproc);
1254 PROC_UNLOCK(bigproc);
1255 wakeup(&cnt.v_free_count);
1256 }
1257 }
1258 }
1259
1260 /*
1261 * This routine tries to maintain the pseudo LRU active queue,
1262 * so that during long periods of time where there is no paging,
1263 * that some statistic accumulation still occurs. This code
1264 * helps the situation where paging just starts to occur.
1265 */
1266 static void
1267 vm_pageout_page_stats()
1268 {
1269 vm_object_t object;
1270 vm_page_t m,next;
1271 int pcount,tpcount; /* Number of pages to check */
1272 static int fullintervalcount = 0;
1273 int page_shortage;
1274
1275 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
1276 page_shortage =
1277 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) -
1278 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count);
1279
1280 if (page_shortage <= 0)
1281 return;
1282
1283 pcount = cnt.v_active_count;
1284 fullintervalcount += vm_pageout_stats_interval;
1285 if (fullintervalcount < vm_pageout_full_stats_interval) {
1286 tpcount = (int64_t)vm_pageout_stats_max * cnt.v_active_count /
1287 cnt.v_page_count;
1288 if (pcount > tpcount)
1289 pcount = tpcount;
1290 } else {
1291 fullintervalcount = 0;
1292 }
1293
1294 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1295 while ((m != NULL) && (pcount-- > 0)) {
1296 int actcount;
1297
1298 KASSERT(VM_PAGE_INQUEUE2(m, PQ_ACTIVE),
1299 ("vm_pageout_page_stats: page %p isn't active", m));
1300
1301 next = TAILQ_NEXT(m, pageq);
1302 object = m->object;
1303
1304 if ((m->flags & PG_MARKER) != 0) {
1305 m = next;
1306 continue;
1307 }
1308 if (!VM_OBJECT_TRYLOCK(object) &&
1309 !vm_pageout_fallback_object_lock(m, &next)) {
1310 VM_OBJECT_UNLOCK(object);
1311 m = next;
1312 continue;
1313 }
1314
1315 /*
1316 * Don't deactivate pages that are busy.
1317 */
1318 if ((m->busy != 0) ||
1319 (m->oflags & VPO_BUSY) ||
1320 (m->hold_count != 0)) {
1321 VM_OBJECT_UNLOCK(object);
1322 vm_pageq_requeue(m);
1323 m = next;
1324 continue;
1325 }
1326
1327 actcount = 0;
1328 if (m->flags & PG_REFERENCED) {
1329 vm_page_flag_clear(m, PG_REFERENCED);
1330 actcount += 1;
1331 }
1332
1333 actcount += pmap_ts_referenced(m);
1334 if (actcount) {
1335 m->act_count += ACT_ADVANCE + actcount;
1336 if (m->act_count > ACT_MAX)
1337 m->act_count = ACT_MAX;
1338 vm_pageq_requeue(m);
1339 } else {
1340 if (m->act_count == 0) {
1341 /*
1342 * We turn off page access, so that we have
1343 * more accurate RSS stats. We don't do this
1344 * in the normal page deactivation when the
1345 * system is loaded VM wise, because the
1346 * cost of the large number of page protect
1347 * operations would be higher than the value
1348 * of doing the operation.
1349 */
1350 pmap_remove_all(m);
1351 vm_page_deactivate(m);
1352 } else {
1353 m->act_count -= min(m->act_count, ACT_DECLINE);
1354 vm_pageq_requeue(m);
1355 }
1356 }
1357 VM_OBJECT_UNLOCK(object);
1358 m = next;
1359 }
1360 }
1361
1362 /*
1363 * vm_pageout is the high level pageout daemon.
1364 */
1365 static void
1366 vm_pageout()
1367 {
1368 int error, pass;
1369
1370 /*
1371 * Initialize some paging parameters.
1372 */
1373 cnt.v_interrupt_free_min = 2;
1374 if (cnt.v_page_count < 2000)
1375 vm_pageout_page_count = 8;
1376
1377 /*
1378 * v_free_reserved needs to include enough for the largest
1379 * swap pager structures plus enough for any pv_entry structs
1380 * when paging.
1381 */
1382 if (cnt.v_page_count > 1024)
1383 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200;
1384 else
1385 cnt.v_free_min = 4;
1386 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE +
1387 cnt.v_interrupt_free_min;
1388 cnt.v_free_reserved = vm_pageout_page_count +
1389 cnt.v_pageout_free_min + (cnt.v_page_count / 768);
1390 cnt.v_free_severe = cnt.v_free_min / 2;
1391 cnt.v_free_min += cnt.v_free_reserved;
1392 cnt.v_free_severe += cnt.v_free_reserved;
1393
1394 /*
1395 * v_free_target and v_cache_min control pageout hysteresis. Note
1396 * that these are more a measure of the VM cache queue hysteresis
1397 * then the VM free queue. Specifically, v_free_target is the
1398 * high water mark (free+cache pages).
1399 *
1400 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the
1401 * low water mark, while v_free_min is the stop. v_cache_min must
1402 * be big enough to handle memory needs while the pageout daemon
1403 * is signalled and run to free more pages.
1404 */
1405 if (cnt.v_free_count > 6144)
1406 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved;
1407 else
1408 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved;
1409
1410 if (cnt.v_free_count > 2048) {
1411 cnt.v_cache_min = cnt.v_free_target;
1412 cnt.v_cache_max = 2 * cnt.v_cache_min;
1413 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2;
1414 } else {
1415 cnt.v_cache_min = 0;
1416 cnt.v_cache_max = 0;
1417 cnt.v_inactive_target = cnt.v_free_count / 4;
1418 }
1419 if (cnt.v_inactive_target > cnt.v_free_count / 3)
1420 cnt.v_inactive_target = cnt.v_free_count / 3;
1421
1422 /* XXX does not really belong here */
1423 if (vm_page_max_wired == 0)
1424 vm_page_max_wired = cnt.v_free_count / 3;
1425
1426 if (vm_pageout_stats_max == 0)
1427 vm_pageout_stats_max = cnt.v_free_target;
1428
1429 /*
1430 * Set interval in seconds for stats scan.
1431 */
1432 if (vm_pageout_stats_interval == 0)
1433 vm_pageout_stats_interval = 5;
1434 if (vm_pageout_full_stats_interval == 0)
1435 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4;
1436
1437 swap_pager_swap_init();
1438 pass = 0;
1439 /*
1440 * The pageout daemon is never done, so loop forever.
1441 */
1442 while (TRUE) {
1443 /*
1444 * If we have enough free memory, wakeup waiters. Do
1445 * not clear vm_pages_needed until we reach our target,
1446 * otherwise we may be woken up over and over again and
1447 * waste a lot of cpu.
1448 */
1449 mtx_lock(&vm_page_queue_free_mtx);
1450 if (vm_pages_needed && !vm_page_count_min()) {
1451 if (!vm_paging_needed())
1452 vm_pages_needed = 0;
1453 wakeup(&cnt.v_free_count);
1454 }
1455 if (vm_pages_needed) {
1456 /*
1457 * Still not done, take a second pass without waiting
1458 * (unlimited dirty cleaning), otherwise sleep a bit
1459 * and try again.
1460 */
1461 ++pass;
1462 if (pass > 1)
1463 msleep(&vm_pages_needed,
1464 &vm_page_queue_free_mtx, PVM, "psleep",
1465 hz / 2);
1466 } else {
1467 /*
1468 * Good enough, sleep & handle stats. Prime the pass
1469 * for the next run.
1470 */
1471 if (pass > 1)
1472 pass = 1;
1473 else
1474 pass = 0;
1475 error = msleep(&vm_pages_needed,
1476 &vm_page_queue_free_mtx, PVM, "psleep",
1477 vm_pageout_stats_interval * hz);
1478 if (error && !vm_pages_needed) {
1479 mtx_unlock(&vm_page_queue_free_mtx);
1480 pass = 0;
1481 vm_page_lock_queues();
1482 vm_pageout_page_stats();
1483 vm_page_unlock_queues();
1484 continue;
1485 }
1486 }
1487 if (vm_pages_needed)
1488 cnt.v_pdwakeups++;
1489 mtx_unlock(&vm_page_queue_free_mtx);
1490 vm_pageout_scan(pass);
1491 }
1492 }
1493
1494 /*
1495 * Unless the free page queue lock is held by the caller, this function
1496 * should be regarded as advisory. Specifically, the caller should
1497 * not msleep() on &cnt.v_free_count following this function unless
1498 * the free page queue lock is held until the msleep() is performed.
1499 */
1500 void
1501 pagedaemon_wakeup()
1502 {
1503
1504 if (!vm_pages_needed && curthread->td_proc != pageproc) {
1505 vm_pages_needed = 1;
1506 wakeup(&vm_pages_needed);
1507 }
1508 }
1509
1510 #if !defined(NO_SWAPPING)
1511 static void
1512 vm_req_vmdaemon(int req)
1513 {
1514 static int lastrun = 0;
1515
1516 mtx_lock(&vm_daemon_mtx);
1517 vm_pageout_req_swapout |= req;
1518 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
1519 wakeup(&vm_daemon_needed);
1520 lastrun = ticks;
1521 }
1522 mtx_unlock(&vm_daemon_mtx);
1523 }
1524
1525 static void
1526 vm_daemon()
1527 {
1528 struct rlimit rsslim;
1529 struct proc *p;
1530 struct thread *td;
1531 int breakout, swapout_flags;
1532
1533 while (TRUE) {
1534 mtx_lock(&vm_daemon_mtx);
1535 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0);
1536 swapout_flags = vm_pageout_req_swapout;
1537 vm_pageout_req_swapout = 0;
1538 mtx_unlock(&vm_daemon_mtx);
1539 if (swapout_flags)
1540 swapout_procs(swapout_flags);
1541
1542 /*
1543 * scan the processes for exceeding their rlimits or if
1544 * process is swapped out -- deactivate pages
1545 */
1546 sx_slock(&allproc_lock);
1547 FOREACH_PROC_IN_SYSTEM(p) {
1548 vm_pindex_t limit, size;
1549
1550 /*
1551 * if this is a system process or if we have already
1552 * looked at this process, skip it.
1553 */
1554 PROC_LOCK(p);
1555 if (p->p_flag & (P_SYSTEM | P_WEXIT)) {
1556 PROC_UNLOCK(p);
1557 continue;
1558 }
1559 /*
1560 * if the process is in a non-running type state,
1561 * don't touch it.
1562 */
1563 PROC_SLOCK(p);
1564 breakout = 0;
1565 FOREACH_THREAD_IN_PROC(p, td) {
1566 thread_lock(td);
1567 if (!TD_ON_RUNQ(td) &&
1568 !TD_IS_RUNNING(td) &&
1569 !TD_IS_SLEEPING(td)) {
1570 thread_unlock(td);
1571 breakout = 1;
1572 break;
1573 }
1574 thread_unlock(td);
1575 }
1576 PROC_SUNLOCK(p);
1577 if (breakout) {
1578 PROC_UNLOCK(p);
1579 continue;
1580 }
1581 /*
1582 * get a limit
1583 */
1584 lim_rlimit(p, RLIMIT_RSS, &rsslim);
1585 limit = OFF_TO_IDX(
1586 qmin(rsslim.rlim_cur, rsslim.rlim_max));
1587
1588 /*
1589 * let processes that are swapped out really be
1590 * swapped out set the limit to nothing (will force a
1591 * swap-out.)
1592 */
1593 if ((p->p_flag & P_INMEM) == 0)
1594 limit = 0; /* XXX */
1595 PROC_UNLOCK(p);
1596
1597 size = vmspace_resident_count(p->p_vmspace);
1598 if (limit >= 0 && size >= limit) {
1599 vm_pageout_map_deactivate_pages(
1600 &p->p_vmspace->vm_map, limit);
1601 }
1602 }
1603 sx_sunlock(&allproc_lock);
1604 }
1605 }
1606 #endif /* !defined(NO_SWAPPING) */
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