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: releng/9.2/sys/vm/vm_pageout.c 240947 2012-09-26 03:54:55Z alc $");
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/racct.h>
90 #include <sys/resourcevar.h>
91 #include <sys/sched.h>
92 #include <sys/signalvar.h>
93 #include <sys/vnode.h>
94 #include <sys/vmmeter.h>
95 #include <sys/sx.h>
96 #include <sys/sysctl.h>
97
98 #include <vm/vm.h>
99 #include <vm/vm_param.h>
100 #include <vm/vm_object.h>
101 #include <vm/vm_page.h>
102 #include <vm/vm_map.h>
103 #include <vm/vm_pageout.h>
104 #include <vm/vm_pager.h>
105 #include <vm/swap_pager.h>
106 #include <vm/vm_extern.h>
107 #include <vm/uma.h>
108
109 /*
110 * System initialization
111 */
112
113 /* the kernel process "vm_pageout"*/
114 static void vm_pageout(void);
115 static int vm_pageout_clean(vm_page_t);
116 static void vm_pageout_scan(int pass);
117
118 struct proc *pageproc;
119
120 static struct kproc_desc page_kp = {
121 "pagedaemon",
122 vm_pageout,
123 &pageproc
124 };
125 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start,
126 &page_kp);
127
128 #if !defined(NO_SWAPPING)
129 /* the kernel process "vm_daemon"*/
130 static void vm_daemon(void);
131 static struct proc *vmproc;
132
133 static struct kproc_desc vm_kp = {
134 "vmdaemon",
135 vm_daemon,
136 &vmproc
137 };
138 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp);
139 #endif
140
141
142 int vm_pages_needed; /* Event on which pageout daemon sleeps */
143 int vm_pageout_deficit; /* Estimated number of pages deficit */
144 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */
145
146 #if !defined(NO_SWAPPING)
147 static int vm_pageout_req_swapout; /* XXX */
148 static int vm_daemon_needed;
149 static struct mtx vm_daemon_mtx;
150 /* Allow for use by vm_pageout before vm_daemon is initialized. */
151 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF);
152 #endif
153 static int vm_max_launder = 32;
154 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0;
155 static int vm_pageout_full_stats_interval = 0;
156 static int vm_pageout_algorithm=0;
157 static int defer_swap_pageouts=0;
158 static int disable_swap_pageouts=0;
159
160 #if defined(NO_SWAPPING)
161 static int vm_swap_enabled=0;
162 static int vm_swap_idle_enabled=0;
163 #else
164 static int vm_swap_enabled=1;
165 static int vm_swap_idle_enabled=0;
166 #endif
167
168 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm,
169 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt");
170
171 SYSCTL_INT(_vm, OID_AUTO, max_launder,
172 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout");
173
174 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max,
175 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length");
176
177 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval,
178 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan");
179
180 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval,
181 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan");
182
183 #if defined(NO_SWAPPING)
184 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
185 CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout");
186 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
187 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
188 #else
189 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
190 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout");
191 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
192 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
193 #endif
194
195 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts,
196 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem");
197
198 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts,
199 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages");
200
201 static int pageout_lock_miss;
202 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss,
203 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout");
204
205 #define VM_PAGEOUT_PAGE_COUNT 16
206 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
207
208 int vm_page_max_wired; /* XXX max # of wired pages system-wide */
209 SYSCTL_INT(_vm, OID_AUTO, max_wired,
210 CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count");
211
212 #if !defined(NO_SWAPPING)
213 static void vm_pageout_map_deactivate_pages(vm_map_t, long);
214 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long);
215 static void vm_req_vmdaemon(int req);
216 #endif
217 static void vm_pageout_page_stats(void);
218
219 /*
220 * Initialize a dummy page for marking the caller's place in the specified
221 * paging queue. In principle, this function only needs to set the flag
222 * PG_MARKER. Nonetheless, it sets the flag VPO_BUSY and initializes the hold
223 * count to one as safety precautions.
224 */
225 static void
226 vm_pageout_init_marker(vm_page_t marker, u_short queue)
227 {
228
229 bzero(marker, sizeof(*marker));
230 marker->flags = PG_MARKER;
231 marker->oflags = VPO_BUSY;
232 marker->queue = queue;
233 marker->hold_count = 1;
234 }
235
236 /*
237 * vm_pageout_fallback_object_lock:
238 *
239 * Lock vm object currently associated with `m'. VM_OBJECT_TRYLOCK is
240 * known to have failed and page queue must be either PQ_ACTIVE or
241 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues
242 * while locking the vm object. Use marker page to detect page queue
243 * changes and maintain notion of next page on page queue. Return
244 * TRUE if no changes were detected, FALSE otherwise. vm object is
245 * locked on return.
246 *
247 * This function depends on both the lock portion of struct vm_object
248 * and normal struct vm_page being type stable.
249 */
250 boolean_t
251 vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next)
252 {
253 struct vm_page marker;
254 boolean_t unchanged;
255 u_short queue;
256 vm_object_t object;
257
258 queue = m->queue;
259 vm_pageout_init_marker(&marker, queue);
260 object = m->object;
261
262 TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl,
263 m, &marker, pageq);
264 vm_page_unlock_queues();
265 vm_page_unlock(m);
266 VM_OBJECT_LOCK(object);
267 vm_page_lock(m);
268 vm_page_lock_queues();
269
270 /* Page queue might have changed. */
271 *next = TAILQ_NEXT(&marker, pageq);
272 unchanged = (m->queue == queue &&
273 m->object == object &&
274 &marker == TAILQ_NEXT(m, pageq));
275 TAILQ_REMOVE(&vm_page_queues[queue].pl,
276 &marker, pageq);
277 return (unchanged);
278 }
279
280 /*
281 * Lock the page while holding the page queue lock. Use marker page
282 * to detect page queue changes and maintain notion of next page on
283 * page queue. Return TRUE if no changes were detected, FALSE
284 * otherwise. The page is locked on return. The page queue lock might
285 * be dropped and reacquired.
286 *
287 * This function depends on normal struct vm_page being type stable.
288 */
289 boolean_t
290 vm_pageout_page_lock(vm_page_t m, vm_page_t *next)
291 {
292 struct vm_page marker;
293 boolean_t unchanged;
294 u_short queue;
295
296 vm_page_lock_assert(m, MA_NOTOWNED);
297 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
298
299 if (vm_page_trylock(m))
300 return (TRUE);
301
302 queue = m->queue;
303 vm_pageout_init_marker(&marker, queue);
304
305 TAILQ_INSERT_AFTER(&vm_page_queues[queue].pl, m, &marker, pageq);
306 vm_page_unlock_queues();
307 vm_page_lock(m);
308 vm_page_lock_queues();
309
310 /* Page queue might have changed. */
311 *next = TAILQ_NEXT(&marker, pageq);
312 unchanged = (m->queue == queue && &marker == TAILQ_NEXT(m, pageq));
313 TAILQ_REMOVE(&vm_page_queues[queue].pl, &marker, pageq);
314 return (unchanged);
315 }
316
317 /*
318 * vm_pageout_clean:
319 *
320 * Clean the page and remove it from the laundry.
321 *
322 * We set the busy bit to cause potential page faults on this page to
323 * block. Note the careful timing, however, the busy bit isn't set till
324 * late and we cannot do anything that will mess with the page.
325 */
326 static int
327 vm_pageout_clean(vm_page_t m)
328 {
329 vm_object_t object;
330 vm_page_t mc[2*vm_pageout_page_count], pb, ps;
331 int pageout_count;
332 int ib, is, page_base;
333 vm_pindex_t pindex = m->pindex;
334
335 vm_page_lock_assert(m, MA_OWNED);
336 object = m->object;
337 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
338
339 /*
340 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP
341 * with the new swapper, but we could have serious problems paging
342 * out other object types if there is insufficient memory.
343 *
344 * Unfortunately, checking free memory here is far too late, so the
345 * check has been moved up a procedural level.
346 */
347
348 /*
349 * Can't clean the page if it's busy or held.
350 */
351 KASSERT(m->busy == 0 && (m->oflags & VPO_BUSY) == 0,
352 ("vm_pageout_clean: page %p is busy", m));
353 KASSERT(m->hold_count == 0, ("vm_pageout_clean: page %p is held", m));
354 vm_page_unlock(m);
355
356 mc[vm_pageout_page_count] = pb = ps = m;
357 pageout_count = 1;
358 page_base = vm_pageout_page_count;
359 ib = 1;
360 is = 1;
361
362 /*
363 * Scan object for clusterable pages.
364 *
365 * We can cluster ONLY if: ->> the page is NOT
366 * clean, wired, busy, held, or mapped into a
367 * buffer, and one of the following:
368 * 1) The page is inactive, or a seldom used
369 * active page.
370 * -or-
371 * 2) we force the issue.
372 *
373 * During heavy mmap/modification loads the pageout
374 * daemon can really fragment the underlying file
375 * due to flushing pages out of order and not trying
376 * align the clusters (which leave sporatic out-of-order
377 * holes). To solve this problem we do the reverse scan
378 * first and attempt to align our cluster, then do a
379 * forward scan if room remains.
380 */
381 more:
382 while (ib && pageout_count < vm_pageout_page_count) {
383 vm_page_t p;
384
385 if (ib > pindex) {
386 ib = 0;
387 break;
388 }
389
390 if ((p = vm_page_prev(pb)) == NULL ||
391 (p->oflags & VPO_BUSY) != 0 || p->busy != 0) {
392 ib = 0;
393 break;
394 }
395 vm_page_lock(p);
396 vm_page_test_dirty(p);
397 if (p->dirty == 0 ||
398 p->queue != PQ_INACTIVE ||
399 p->hold_count != 0) { /* may be undergoing I/O */
400 vm_page_unlock(p);
401 ib = 0;
402 break;
403 }
404 vm_page_unlock(p);
405 mc[--page_base] = pb = p;
406 ++pageout_count;
407 ++ib;
408 /*
409 * alignment boundry, stop here and switch directions. Do
410 * not clear ib.
411 */
412 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0)
413 break;
414 }
415
416 while (pageout_count < vm_pageout_page_count &&
417 pindex + is < object->size) {
418 vm_page_t p;
419
420 if ((p = vm_page_next(ps)) == NULL ||
421 (p->oflags & VPO_BUSY) != 0 || p->busy != 0)
422 break;
423 vm_page_lock(p);
424 vm_page_test_dirty(p);
425 if (p->dirty == 0 ||
426 p->queue != PQ_INACTIVE ||
427 p->hold_count != 0) { /* may be undergoing I/O */
428 vm_page_unlock(p);
429 break;
430 }
431 vm_page_unlock(p);
432 mc[page_base + pageout_count] = ps = p;
433 ++pageout_count;
434 ++is;
435 }
436
437 /*
438 * If we exhausted our forward scan, continue with the reverse scan
439 * when possible, even past a page boundry. This catches boundry
440 * conditions.
441 */
442 if (ib && pageout_count < vm_pageout_page_count)
443 goto more;
444
445 /*
446 * we allow reads during pageouts...
447 */
448 return (vm_pageout_flush(&mc[page_base], pageout_count, 0, 0, NULL,
449 NULL));
450 }
451
452 /*
453 * vm_pageout_flush() - launder the given pages
454 *
455 * The given pages are laundered. Note that we setup for the start of
456 * I/O ( i.e. busy the page ), mark it read-only, and bump the object
457 * reference count all in here rather then in the parent. If we want
458 * the parent to do more sophisticated things we may have to change
459 * the ordering.
460 *
461 * Returned runlen is the count of pages between mreq and first
462 * page after mreq with status VM_PAGER_AGAIN.
463 * *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL
464 * for any page in runlen set.
465 */
466 int
467 vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen,
468 boolean_t *eio)
469 {
470 vm_object_t object = mc[0]->object;
471 int pageout_status[count];
472 int numpagedout = 0;
473 int i, runlen;
474
475 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
476 mtx_assert(&vm_page_queue_mtx, MA_NOTOWNED);
477
478 /*
479 * Initiate I/O. Bump the vm_page_t->busy counter and
480 * mark the pages read-only.
481 *
482 * We do not have to fixup the clean/dirty bits here... we can
483 * allow the pager to do it after the I/O completes.
484 *
485 * NOTE! mc[i]->dirty may be partial or fragmented due to an
486 * edge case with file fragments.
487 */
488 for (i = 0; i < count; i++) {
489 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL,
490 ("vm_pageout_flush: partially invalid page %p index %d/%d",
491 mc[i], i, count));
492 vm_page_io_start(mc[i]);
493 pmap_remove_write(mc[i]);
494 }
495 vm_object_pip_add(object, count);
496
497 vm_pager_put_pages(object, mc, count, flags, pageout_status);
498
499 runlen = count - mreq;
500 if (eio != NULL)
501 *eio = FALSE;
502 for (i = 0; i < count; i++) {
503 vm_page_t mt = mc[i];
504
505 KASSERT(pageout_status[i] == VM_PAGER_PEND ||
506 !pmap_page_is_write_mapped(mt),
507 ("vm_pageout_flush: page %p is not write protected", mt));
508 switch (pageout_status[i]) {
509 case VM_PAGER_OK:
510 case VM_PAGER_PEND:
511 numpagedout++;
512 break;
513 case VM_PAGER_BAD:
514 /*
515 * Page outside of range of object. Right now we
516 * essentially lose the changes by pretending it
517 * worked.
518 */
519 vm_page_undirty(mt);
520 break;
521 case VM_PAGER_ERROR:
522 case VM_PAGER_FAIL:
523 /*
524 * If page couldn't be paged out, then reactivate the
525 * page so it doesn't clog the inactive list. (We
526 * will try paging out it again later).
527 */
528 vm_page_lock(mt);
529 vm_page_activate(mt);
530 vm_page_unlock(mt);
531 if (eio != NULL && i >= mreq && i - mreq < runlen)
532 *eio = TRUE;
533 break;
534 case VM_PAGER_AGAIN:
535 if (i >= mreq && i - mreq < runlen)
536 runlen = i - mreq;
537 break;
538 }
539
540 /*
541 * If the operation is still going, leave the page busy to
542 * block all other accesses. Also, leave the paging in
543 * progress indicator set so that we don't attempt an object
544 * collapse.
545 */
546 if (pageout_status[i] != VM_PAGER_PEND) {
547 vm_object_pip_wakeup(object);
548 vm_page_io_finish(mt);
549 if (vm_page_count_severe()) {
550 vm_page_lock(mt);
551 vm_page_try_to_cache(mt);
552 vm_page_unlock(mt);
553 }
554 }
555 }
556 if (prunlen != NULL)
557 *prunlen = runlen;
558 return (numpagedout);
559 }
560
561 #if !defined(NO_SWAPPING)
562 /*
563 * vm_pageout_object_deactivate_pages
564 *
565 * Deactivate enough pages to satisfy the inactive target
566 * requirements.
567 *
568 * The object and map must be locked.
569 */
570 static void
571 vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object,
572 long desired)
573 {
574 vm_object_t backing_object, object;
575 vm_page_t p;
576 int actcount, remove_mode;
577
578 VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED);
579 if (first_object->type == OBJT_DEVICE ||
580 first_object->type == OBJT_SG)
581 return;
582 for (object = first_object;; object = backing_object) {
583 if (pmap_resident_count(pmap) <= desired)
584 goto unlock_return;
585 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
586 if (object->type == OBJT_PHYS || object->paging_in_progress)
587 goto unlock_return;
588
589 remove_mode = 0;
590 if (object->shadow_count > 1)
591 remove_mode = 1;
592 /*
593 * Scan the object's entire memory queue.
594 */
595 TAILQ_FOREACH(p, &object->memq, listq) {
596 if (pmap_resident_count(pmap) <= desired)
597 goto unlock_return;
598 if ((p->oflags & VPO_BUSY) != 0 || p->busy != 0)
599 continue;
600 PCPU_INC(cnt.v_pdpages);
601 vm_page_lock(p);
602 if (p->wire_count != 0 || p->hold_count != 0 ||
603 !pmap_page_exists_quick(pmap, p)) {
604 vm_page_unlock(p);
605 continue;
606 }
607 actcount = pmap_ts_referenced(p);
608 if ((p->aflags & PGA_REFERENCED) != 0) {
609 if (actcount == 0)
610 actcount = 1;
611 vm_page_aflag_clear(p, PGA_REFERENCED);
612 }
613 if (p->queue != PQ_ACTIVE && actcount != 0) {
614 vm_page_activate(p);
615 p->act_count += actcount;
616 } else if (p->queue == PQ_ACTIVE) {
617 if (actcount == 0) {
618 p->act_count -= min(p->act_count,
619 ACT_DECLINE);
620 if (!remove_mode &&
621 (vm_pageout_algorithm ||
622 p->act_count == 0)) {
623 pmap_remove_all(p);
624 vm_page_deactivate(p);
625 } else {
626 vm_page_lock_queues();
627 vm_page_requeue(p);
628 vm_page_unlock_queues();
629 }
630 } else {
631 vm_page_activate(p);
632 if (p->act_count < ACT_MAX -
633 ACT_ADVANCE)
634 p->act_count += ACT_ADVANCE;
635 vm_page_lock_queues();
636 vm_page_requeue(p);
637 vm_page_unlock_queues();
638 }
639 } else if (p->queue == PQ_INACTIVE)
640 pmap_remove_all(p);
641 vm_page_unlock(p);
642 }
643 if ((backing_object = object->backing_object) == NULL)
644 goto unlock_return;
645 VM_OBJECT_LOCK(backing_object);
646 if (object != first_object)
647 VM_OBJECT_UNLOCK(object);
648 }
649 unlock_return:
650 if (object != first_object)
651 VM_OBJECT_UNLOCK(object);
652 }
653
654 /*
655 * deactivate some number of pages in a map, try to do it fairly, but
656 * that is really hard to do.
657 */
658 static void
659 vm_pageout_map_deactivate_pages(map, desired)
660 vm_map_t map;
661 long desired;
662 {
663 vm_map_entry_t tmpe;
664 vm_object_t obj, bigobj;
665 int nothingwired;
666
667 if (!vm_map_trylock(map))
668 return;
669
670 bigobj = NULL;
671 nothingwired = TRUE;
672
673 /*
674 * first, search out the biggest object, and try to free pages from
675 * that.
676 */
677 tmpe = map->header.next;
678 while (tmpe != &map->header) {
679 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
680 obj = tmpe->object.vm_object;
681 if (obj != NULL && VM_OBJECT_TRYLOCK(obj)) {
682 if (obj->shadow_count <= 1 &&
683 (bigobj == NULL ||
684 bigobj->resident_page_count < obj->resident_page_count)) {
685 if (bigobj != NULL)
686 VM_OBJECT_UNLOCK(bigobj);
687 bigobj = obj;
688 } else
689 VM_OBJECT_UNLOCK(obj);
690 }
691 }
692 if (tmpe->wired_count > 0)
693 nothingwired = FALSE;
694 tmpe = tmpe->next;
695 }
696
697 if (bigobj != NULL) {
698 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired);
699 VM_OBJECT_UNLOCK(bigobj);
700 }
701 /*
702 * Next, hunt around for other pages to deactivate. We actually
703 * do this search sort of wrong -- .text first is not the best idea.
704 */
705 tmpe = map->header.next;
706 while (tmpe != &map->header) {
707 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
708 break;
709 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
710 obj = tmpe->object.vm_object;
711 if (obj != NULL) {
712 VM_OBJECT_LOCK(obj);
713 vm_pageout_object_deactivate_pages(map->pmap, obj, desired);
714 VM_OBJECT_UNLOCK(obj);
715 }
716 }
717 tmpe = tmpe->next;
718 }
719
720 /*
721 * Remove all mappings if a process is swapped out, this will free page
722 * table pages.
723 */
724 if (desired == 0 && nothingwired) {
725 pmap_remove(vm_map_pmap(map), vm_map_min(map),
726 vm_map_max(map));
727 }
728 vm_map_unlock(map);
729 }
730 #endif /* !defined(NO_SWAPPING) */
731
732 /*
733 * vm_pageout_scan does the dirty work for the pageout daemon.
734 */
735 static void
736 vm_pageout_scan(int pass)
737 {
738 vm_page_t m, next;
739 struct vm_page marker;
740 int page_shortage, maxscan, pcount;
741 int addl_page_shortage;
742 vm_object_t object;
743 int actcount;
744 int vnodes_skipped = 0;
745 int maxlaunder;
746 boolean_t queues_locked;
747
748 /*
749 * Decrease registered cache sizes.
750 */
751 EVENTHANDLER_INVOKE(vm_lowmem, 0);
752 /*
753 * We do this explicitly after the caches have been drained above.
754 */
755 uma_reclaim();
756
757 /*
758 * The addl_page_shortage is the number of temporarily
759 * stuck pages in the inactive queue. In other words, the
760 * number of pages from cnt.v_inactive_count that should be
761 * discounted in setting the target for the active queue scan.
762 */
763 addl_page_shortage = atomic_readandclear_int(&vm_pageout_deficit);
764
765 /*
766 * Calculate the number of pages we want to either free or move
767 * to the cache.
768 */
769 page_shortage = vm_paging_target() + addl_page_shortage;
770
771 vm_pageout_init_marker(&marker, PQ_INACTIVE);
772
773 /*
774 * Start scanning the inactive queue for pages we can move to the
775 * cache or free. The scan will stop when the target is reached or
776 * we have scanned the entire inactive queue. Note that m->act_count
777 * is not used to form decisions for the inactive queue, only for the
778 * active queue.
779 *
780 * maxlaunder limits the number of dirty pages we flush per scan.
781 * For most systems a smaller value (16 or 32) is more robust under
782 * extreme memory and disk pressure because any unnecessary writes
783 * to disk can result in extreme performance degredation. However,
784 * systems with excessive dirty pages (especially when MAP_NOSYNC is
785 * used) will die horribly with limited laundering. If the pageout
786 * daemon cannot clean enough pages in the first pass, we let it go
787 * all out in succeeding passes.
788 */
789 if ((maxlaunder = vm_max_launder) <= 1)
790 maxlaunder = 1;
791 if (pass)
792 maxlaunder = 10000;
793 vm_page_lock_queues();
794 queues_locked = TRUE;
795 maxscan = cnt.v_inactive_count;
796
797 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl);
798 m != NULL && maxscan-- > 0 && page_shortage > 0;
799 m = next) {
800 KASSERT(queues_locked, ("unlocked queues"));
801 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
802 KASSERT(m->queue == PQ_INACTIVE, ("Inactive queue %p", m));
803
804 cnt.v_pdpages++;
805 next = TAILQ_NEXT(m, pageq);
806
807 /*
808 * skip marker pages
809 */
810 if (m->flags & PG_MARKER)
811 continue;
812
813 KASSERT((m->flags & PG_FICTITIOUS) == 0,
814 ("Fictitious page %p cannot be in inactive queue", m));
815 KASSERT((m->oflags & VPO_UNMANAGED) == 0,
816 ("Unmanaged page %p cannot be in inactive queue", m));
817
818 /*
819 * The page or object lock acquisitions fail if the
820 * page was removed from the queue or moved to a
821 * different position within the queue. In either
822 * case, addl_page_shortage should not be incremented.
823 */
824 if (!vm_pageout_page_lock(m, &next)) {
825 vm_page_unlock(m);
826 continue;
827 }
828 object = m->object;
829 if (!VM_OBJECT_TRYLOCK(object) &&
830 !vm_pageout_fallback_object_lock(m, &next)) {
831 vm_page_unlock(m);
832 VM_OBJECT_UNLOCK(object);
833 continue;
834 }
835
836 /*
837 * Don't mess with busy pages, keep them at at the
838 * front of the queue, most likely they are being
839 * paged out. Increment addl_page_shortage for busy
840 * pages, because they may leave the inactive queue
841 * shortly after page scan is finished.
842 */
843 if (m->busy != 0 || (m->oflags & VPO_BUSY) != 0) {
844 vm_page_unlock(m);
845 VM_OBJECT_UNLOCK(object);
846 addl_page_shortage++;
847 continue;
848 }
849
850 /*
851 * We unlock vm_page_queue_mtx, invalidating the
852 * 'next' pointer. Use our marker to remember our
853 * place.
854 */
855 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl,
856 m, &marker, pageq);
857 vm_page_unlock_queues();
858 queues_locked = FALSE;
859
860 /*
861 * If the object is not being used, we ignore previous
862 * references.
863 */
864 if (object->ref_count == 0) {
865 vm_page_aflag_clear(m, PGA_REFERENCED);
866 KASSERT(!pmap_page_is_mapped(m),
867 ("vm_pageout_scan: page %p is mapped", m));
868
869 /*
870 * Otherwise, if the page has been referenced while in the
871 * inactive queue, we bump the "activation count" upwards,
872 * making it less likely that the page will be added back to
873 * the inactive queue prematurely again. Here we check the
874 * page tables (or emulated bits, if any), given the upper
875 * level VM system not knowing anything about existing
876 * references.
877 */
878 } else if ((m->aflags & PGA_REFERENCED) == 0 &&
879 (actcount = pmap_ts_referenced(m)) != 0) {
880 vm_page_activate(m);
881 vm_page_unlock(m);
882 m->act_count += actcount + ACT_ADVANCE;
883 VM_OBJECT_UNLOCK(object);
884 goto relock_queues;
885 }
886
887 /*
888 * If the upper level VM system knows about any page
889 * references, we activate the page. We also set the
890 * "activation count" higher than normal so that we will less
891 * likely place pages back onto the inactive queue again.
892 */
893 if ((m->aflags & PGA_REFERENCED) != 0) {
894 vm_page_aflag_clear(m, PGA_REFERENCED);
895 actcount = pmap_ts_referenced(m);
896 vm_page_activate(m);
897 vm_page_unlock(m);
898 m->act_count += actcount + ACT_ADVANCE + 1;
899 VM_OBJECT_UNLOCK(object);
900 goto relock_queues;
901 }
902
903 if (m->hold_count != 0) {
904 vm_page_unlock(m);
905 VM_OBJECT_UNLOCK(object);
906
907 /*
908 * Held pages are essentially stuck in the
909 * queue. So, they ought to be discounted
910 * from cnt.v_inactive_count. See the
911 * calculation of the page_shortage for the
912 * loop over the active queue below.
913 */
914 addl_page_shortage++;
915 goto relock_queues;
916 }
917
918 /*
919 * If the upper level VM system does not believe that the page
920 * is fully dirty, but it is mapped for write access, then we
921 * consult the pmap to see if the page's dirty status should
922 * be updated.
923 */
924 if (m->dirty != VM_PAGE_BITS_ALL &&
925 pmap_page_is_write_mapped(m)) {
926 /*
927 * Avoid a race condition: Unless write access is
928 * removed from the page, another processor could
929 * modify it before all access is removed by the call
930 * to vm_page_cache() below. If vm_page_cache() finds
931 * that the page has been modified when it removes all
932 * access, it panics because it cannot cache dirty
933 * pages. In principle, we could eliminate just write
934 * access here rather than all access. In the expected
935 * case, when there are no last instant modifications
936 * to the page, removing all access will be cheaper
937 * overall.
938 */
939 if (pmap_is_modified(m))
940 vm_page_dirty(m);
941 else if (m->dirty == 0)
942 pmap_remove_all(m);
943 }
944
945 if (m->valid == 0) {
946 /*
947 * Invalid pages can be easily freed
948 */
949 vm_page_free(m);
950 PCPU_INC(cnt.v_dfree);
951 --page_shortage;
952 } else if (m->dirty == 0) {
953 /*
954 * Clean pages can be placed onto the cache queue.
955 * This effectively frees them.
956 */
957 vm_page_cache(m);
958 --page_shortage;
959 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) {
960 /*
961 * Dirty pages need to be paged out, but flushing
962 * a page is extremely expensive verses freeing
963 * a clean page. Rather then artificially limiting
964 * the number of pages we can flush, we instead give
965 * dirty pages extra priority on the inactive queue
966 * by forcing them to be cycled through the queue
967 * twice before being flushed, after which the
968 * (now clean) page will cycle through once more
969 * before being freed. This significantly extends
970 * the thrash point for a heavily loaded machine.
971 */
972 m->flags |= PG_WINATCFLS;
973 vm_page_lock_queues();
974 queues_locked = TRUE;
975 vm_page_requeue(m);
976 } else if (maxlaunder > 0) {
977 /*
978 * We always want to try to flush some dirty pages if
979 * we encounter them, to keep the system stable.
980 * Normally this number is small, but under extreme
981 * pressure where there are insufficient clean pages
982 * on the inactive queue, we may have to go all out.
983 */
984 int swap_pageouts_ok, vfslocked = 0;
985 struct vnode *vp = NULL;
986 struct mount *mp = NULL;
987
988 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) {
989 swap_pageouts_ok = 1;
990 } else {
991 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts);
992 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts &&
993 vm_page_count_min());
994
995 }
996
997 /*
998 * We don't bother paging objects that are "dead".
999 * Those objects are in a "rundown" state.
1000 */
1001 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
1002 vm_page_lock_queues();
1003 vm_page_unlock(m);
1004 VM_OBJECT_UNLOCK(object);
1005 queues_locked = TRUE;
1006 vm_page_requeue(m);
1007 goto relock_queues;
1008 }
1009
1010 /*
1011 * The object is already known NOT to be dead. It
1012 * is possible for the vget() to block the whole
1013 * pageout daemon, but the new low-memory handling
1014 * code should prevent it.
1015 *
1016 * The previous code skipped locked vnodes and, worse,
1017 * reordered pages in the queue. This results in
1018 * completely non-deterministic operation and, on a
1019 * busy system, can lead to extremely non-optimal
1020 * pageouts. For example, it can cause clean pages
1021 * to be freed and dirty pages to be moved to the end
1022 * of the queue. Since dirty pages are also moved to
1023 * the end of the queue once-cleaned, this gives
1024 * way too large a weighting to defering the freeing
1025 * of dirty pages.
1026 *
1027 * We can't wait forever for the vnode lock, we might
1028 * deadlock due to a vn_read() getting stuck in
1029 * vm_wait while holding this vnode. We skip the
1030 * vnode if we can't get it in a reasonable amount
1031 * of time.
1032 */
1033 if (object->type == OBJT_VNODE) {
1034 vm_page_unlock(m);
1035 vp = object->handle;
1036 if (vp->v_type == VREG &&
1037 vn_start_write(vp, &mp, V_NOWAIT) != 0) {
1038 mp = NULL;
1039 ++pageout_lock_miss;
1040 if (object->flags & OBJ_MIGHTBEDIRTY)
1041 vnodes_skipped++;
1042 goto unlock_and_continue;
1043 }
1044 KASSERT(mp != NULL,
1045 ("vp %p with NULL v_mount", vp));
1046 vm_object_reference_locked(object);
1047 VM_OBJECT_UNLOCK(object);
1048 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
1049 if (vget(vp, LK_EXCLUSIVE | LK_TIMELOCK,
1050 curthread)) {
1051 VM_OBJECT_LOCK(object);
1052 ++pageout_lock_miss;
1053 if (object->flags & OBJ_MIGHTBEDIRTY)
1054 vnodes_skipped++;
1055 vp = NULL;
1056 goto unlock_and_continue;
1057 }
1058 VM_OBJECT_LOCK(object);
1059 vm_page_lock(m);
1060 vm_page_lock_queues();
1061 queues_locked = TRUE;
1062 /*
1063 * The page might have been moved to another
1064 * queue during potential blocking in vget()
1065 * above. The page might have been freed and
1066 * reused for another vnode.
1067 */
1068 if (m->queue != PQ_INACTIVE ||
1069 m->object != object ||
1070 TAILQ_NEXT(m, pageq) != &marker) {
1071 vm_page_unlock(m);
1072 if (object->flags & OBJ_MIGHTBEDIRTY)
1073 vnodes_skipped++;
1074 goto unlock_and_continue;
1075 }
1076
1077 /*
1078 * The page may have been busied during the
1079 * blocking in vget(). We don't move the
1080 * page back onto the end of the queue so that
1081 * statistics are more correct if we don't.
1082 */
1083 if (m->busy || (m->oflags & VPO_BUSY)) {
1084 vm_page_unlock(m);
1085 goto unlock_and_continue;
1086 }
1087
1088 /*
1089 * If the page has become held it might
1090 * be undergoing I/O, so skip it
1091 */
1092 if (m->hold_count) {
1093 vm_page_unlock(m);
1094 vm_page_requeue(m);
1095 if (object->flags & OBJ_MIGHTBEDIRTY)
1096 vnodes_skipped++;
1097 goto unlock_and_continue;
1098 }
1099 vm_page_unlock_queues();
1100 queues_locked = FALSE;
1101 }
1102
1103 /*
1104 * If a page is dirty, then it is either being washed
1105 * (but not yet cleaned) or it is still in the
1106 * laundry. If it is still in the laundry, then we
1107 * start the cleaning operation.
1108 *
1109 * decrement page_shortage on success to account for
1110 * the (future) cleaned page. Otherwise we could wind
1111 * up laundering or cleaning too many pages.
1112 */
1113 if (vm_pageout_clean(m) != 0) {
1114 --page_shortage;
1115 --maxlaunder;
1116 }
1117 unlock_and_continue:
1118 vm_page_lock_assert(m, MA_NOTOWNED);
1119 VM_OBJECT_UNLOCK(object);
1120 if (mp != NULL) {
1121 if (queues_locked) {
1122 vm_page_unlock_queues();
1123 queues_locked = FALSE;
1124 }
1125 if (vp != NULL)
1126 vput(vp);
1127 VFS_UNLOCK_GIANT(vfslocked);
1128 vm_object_deallocate(object);
1129 vn_finished_write(mp);
1130 }
1131 vm_page_lock_assert(m, MA_NOTOWNED);
1132 goto relock_queues;
1133 }
1134 vm_page_unlock(m);
1135 VM_OBJECT_UNLOCK(object);
1136 relock_queues:
1137 if (!queues_locked) {
1138 vm_page_lock_queues();
1139 queues_locked = TRUE;
1140 }
1141 next = TAILQ_NEXT(&marker, pageq);
1142 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl,
1143 &marker, pageq);
1144 }
1145
1146 /*
1147 * Compute the number of pages we want to try to move from the
1148 * active queue to the inactive queue.
1149 */
1150 page_shortage = vm_paging_target() +
1151 cnt.v_inactive_target - cnt.v_inactive_count;
1152 page_shortage += addl_page_shortage;
1153
1154 /*
1155 * Scan the active queue for things we can deactivate. We nominally
1156 * track the per-page activity counter and use it to locate
1157 * deactivation candidates.
1158 */
1159 pcount = cnt.v_active_count;
1160 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1161 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
1162
1163 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) {
1164
1165 KASSERT(m->queue == PQ_ACTIVE,
1166 ("vm_pageout_scan: page %p isn't active", m));
1167
1168 next = TAILQ_NEXT(m, pageq);
1169 if ((m->flags & PG_MARKER) != 0) {
1170 m = next;
1171 continue;
1172 }
1173 KASSERT((m->flags & PG_FICTITIOUS) == 0,
1174 ("Fictitious page %p cannot be in active queue", m));
1175 KASSERT((m->oflags & VPO_UNMANAGED) == 0,
1176 ("Unmanaged page %p cannot be in active queue", m));
1177 if (!vm_pageout_page_lock(m, &next)) {
1178 vm_page_unlock(m);
1179 m = next;
1180 continue;
1181 }
1182 object = m->object;
1183 if (!VM_OBJECT_TRYLOCK(object) &&
1184 !vm_pageout_fallback_object_lock(m, &next)) {
1185 VM_OBJECT_UNLOCK(object);
1186 vm_page_unlock(m);
1187 m = next;
1188 continue;
1189 }
1190
1191 /*
1192 * Don't deactivate pages that are busy.
1193 */
1194 if ((m->busy != 0) ||
1195 (m->oflags & VPO_BUSY) ||
1196 (m->hold_count != 0)) {
1197 vm_page_unlock(m);
1198 VM_OBJECT_UNLOCK(object);
1199 vm_page_requeue(m);
1200 m = next;
1201 continue;
1202 }
1203
1204 /*
1205 * The count for pagedaemon pages is done after checking the
1206 * page for eligibility...
1207 */
1208 cnt.v_pdpages++;
1209
1210 /*
1211 * Check to see "how much" the page has been used.
1212 */
1213 actcount = 0;
1214 if (object->ref_count != 0) {
1215 if (m->aflags & PGA_REFERENCED) {
1216 actcount += 1;
1217 }
1218 actcount += pmap_ts_referenced(m);
1219 if (actcount) {
1220 m->act_count += ACT_ADVANCE + actcount;
1221 if (m->act_count > ACT_MAX)
1222 m->act_count = ACT_MAX;
1223 }
1224 }
1225
1226 /*
1227 * Since we have "tested" this bit, we need to clear it now.
1228 */
1229 vm_page_aflag_clear(m, PGA_REFERENCED);
1230
1231 /*
1232 * Only if an object is currently being used, do we use the
1233 * page activation count stats.
1234 */
1235 if (actcount && (object->ref_count != 0)) {
1236 vm_page_requeue(m);
1237 } else {
1238 m->act_count -= min(m->act_count, ACT_DECLINE);
1239 if (vm_pageout_algorithm ||
1240 object->ref_count == 0 ||
1241 m->act_count == 0) {
1242 page_shortage--;
1243 if (object->ref_count == 0) {
1244 KASSERT(!pmap_page_is_mapped(m),
1245 ("vm_pageout_scan: page %p is mapped", m));
1246 if (m->dirty == 0)
1247 vm_page_cache(m);
1248 else
1249 vm_page_deactivate(m);
1250 } else {
1251 vm_page_deactivate(m);
1252 }
1253 } else {
1254 vm_page_requeue(m);
1255 }
1256 }
1257 vm_page_unlock(m);
1258 VM_OBJECT_UNLOCK(object);
1259 m = next;
1260 }
1261 vm_page_unlock_queues();
1262 #if !defined(NO_SWAPPING)
1263 /*
1264 * Idle process swapout -- run once per second.
1265 */
1266 if (vm_swap_idle_enabled) {
1267 static long lsec;
1268 if (time_second != lsec) {
1269 vm_req_vmdaemon(VM_SWAP_IDLE);
1270 lsec = time_second;
1271 }
1272 }
1273 #endif
1274
1275 /*
1276 * If we didn't get enough free pages, and we have skipped a vnode
1277 * in a writeable object, wakeup the sync daemon. And kick swapout
1278 * if we did not get enough free pages.
1279 */
1280 if (vm_paging_target() > 0) {
1281 if (vnodes_skipped && vm_page_count_min())
1282 (void) speedup_syncer();
1283 #if !defined(NO_SWAPPING)
1284 if (vm_swap_enabled && vm_page_count_target())
1285 vm_req_vmdaemon(VM_SWAP_NORMAL);
1286 #endif
1287 }
1288
1289 /*
1290 * If we are critically low on one of RAM or swap and low on
1291 * the other, kill the largest process. However, we avoid
1292 * doing this on the first pass in order to give ourselves a
1293 * chance to flush out dirty vnode-backed pages and to allow
1294 * active pages to be moved to the inactive queue and reclaimed.
1295 */
1296 if (pass != 0 &&
1297 ((swap_pager_avail < 64 && vm_page_count_min()) ||
1298 (swap_pager_full && vm_paging_target() > 0)))
1299 vm_pageout_oom(VM_OOM_MEM);
1300 }
1301
1302
1303 void
1304 vm_pageout_oom(int shortage)
1305 {
1306 struct proc *p, *bigproc;
1307 vm_offset_t size, bigsize;
1308 struct thread *td;
1309 struct vmspace *vm;
1310
1311 /*
1312 * We keep the process bigproc locked once we find it to keep anyone
1313 * from messing with it; however, there is a possibility of
1314 * deadlock if process B is bigproc and one of it's child processes
1315 * attempts to propagate a signal to B while we are waiting for A's
1316 * lock while walking this list. To avoid this, we don't block on
1317 * the process lock but just skip a process if it is already locked.
1318 */
1319 bigproc = NULL;
1320 bigsize = 0;
1321 sx_slock(&allproc_lock);
1322 FOREACH_PROC_IN_SYSTEM(p) {
1323 int breakout;
1324
1325 if (PROC_TRYLOCK(p) == 0)
1326 continue;
1327 /*
1328 * If this is a system, protected or killed process, skip it.
1329 */
1330 if (p->p_state != PRS_NORMAL ||
1331 (p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM)) ||
1332 (p->p_pid == 1) || P_KILLED(p) ||
1333 ((p->p_pid < 48) && (swap_pager_avail != 0))) {
1334 PROC_UNLOCK(p);
1335 continue;
1336 }
1337 /*
1338 * If the process is in a non-running type state,
1339 * don't touch it. Check all the threads individually.
1340 */
1341 breakout = 0;
1342 FOREACH_THREAD_IN_PROC(p, td) {
1343 thread_lock(td);
1344 if (!TD_ON_RUNQ(td) &&
1345 !TD_IS_RUNNING(td) &&
1346 !TD_IS_SLEEPING(td) &&
1347 !TD_IS_SUSPENDED(td)) {
1348 thread_unlock(td);
1349 breakout = 1;
1350 break;
1351 }
1352 thread_unlock(td);
1353 }
1354 if (breakout) {
1355 PROC_UNLOCK(p);
1356 continue;
1357 }
1358 /*
1359 * get the process size
1360 */
1361 vm = vmspace_acquire_ref(p);
1362 if (vm == NULL) {
1363 PROC_UNLOCK(p);
1364 continue;
1365 }
1366 if (!vm_map_trylock_read(&vm->vm_map)) {
1367 vmspace_free(vm);
1368 PROC_UNLOCK(p);
1369 continue;
1370 }
1371 size = vmspace_swap_count(vm);
1372 vm_map_unlock_read(&vm->vm_map);
1373 if (shortage == VM_OOM_MEM)
1374 size += vmspace_resident_count(vm);
1375 vmspace_free(vm);
1376 /*
1377 * if the this process is bigger than the biggest one
1378 * remember it.
1379 */
1380 if (size > bigsize) {
1381 if (bigproc != NULL)
1382 PROC_UNLOCK(bigproc);
1383 bigproc = p;
1384 bigsize = size;
1385 } else
1386 PROC_UNLOCK(p);
1387 }
1388 sx_sunlock(&allproc_lock);
1389 if (bigproc != NULL) {
1390 killproc(bigproc, "out of swap space");
1391 sched_nice(bigproc, PRIO_MIN);
1392 PROC_UNLOCK(bigproc);
1393 wakeup(&cnt.v_free_count);
1394 }
1395 }
1396
1397 /*
1398 * This routine tries to maintain the pseudo LRU active queue,
1399 * so that during long periods of time where there is no paging,
1400 * that some statistic accumulation still occurs. This code
1401 * helps the situation where paging just starts to occur.
1402 */
1403 static void
1404 vm_pageout_page_stats()
1405 {
1406 vm_object_t object;
1407 vm_page_t m,next;
1408 int pcount,tpcount; /* Number of pages to check */
1409 static int fullintervalcount = 0;
1410 int page_shortage;
1411
1412 page_shortage =
1413 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) -
1414 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count);
1415
1416 if (page_shortage <= 0)
1417 return;
1418
1419 vm_page_lock_queues();
1420 pcount = cnt.v_active_count;
1421 fullintervalcount += vm_pageout_stats_interval;
1422 if (fullintervalcount < vm_pageout_full_stats_interval) {
1423 tpcount = (int64_t)vm_pageout_stats_max * cnt.v_active_count /
1424 cnt.v_page_count;
1425 if (pcount > tpcount)
1426 pcount = tpcount;
1427 } else {
1428 fullintervalcount = 0;
1429 }
1430
1431 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1432 while ((m != NULL) && (pcount-- > 0)) {
1433 int actcount;
1434
1435 KASSERT(m->queue == PQ_ACTIVE,
1436 ("vm_pageout_page_stats: page %p isn't active", m));
1437
1438 next = TAILQ_NEXT(m, pageq);
1439 if ((m->flags & PG_MARKER) != 0) {
1440 m = next;
1441 continue;
1442 }
1443 vm_page_lock_assert(m, MA_NOTOWNED);
1444 if (!vm_pageout_page_lock(m, &next)) {
1445 vm_page_unlock(m);
1446 m = next;
1447 continue;
1448 }
1449 object = m->object;
1450 if (!VM_OBJECT_TRYLOCK(object) &&
1451 !vm_pageout_fallback_object_lock(m, &next)) {
1452 VM_OBJECT_UNLOCK(object);
1453 vm_page_unlock(m);
1454 m = next;
1455 continue;
1456 }
1457
1458 /*
1459 * Don't deactivate pages that are busy.
1460 */
1461 if ((m->busy != 0) ||
1462 (m->oflags & VPO_BUSY) ||
1463 (m->hold_count != 0)) {
1464 vm_page_unlock(m);
1465 VM_OBJECT_UNLOCK(object);
1466 vm_page_requeue(m);
1467 m = next;
1468 continue;
1469 }
1470
1471 actcount = 0;
1472 if (m->aflags & PGA_REFERENCED) {
1473 vm_page_aflag_clear(m, PGA_REFERENCED);
1474 actcount += 1;
1475 }
1476
1477 actcount += pmap_ts_referenced(m);
1478 if (actcount) {
1479 m->act_count += ACT_ADVANCE + actcount;
1480 if (m->act_count > ACT_MAX)
1481 m->act_count = ACT_MAX;
1482 vm_page_requeue(m);
1483 } else {
1484 if (m->act_count == 0) {
1485 /*
1486 * We turn off page access, so that we have
1487 * more accurate RSS stats. We don't do this
1488 * in the normal page deactivation when the
1489 * system is loaded VM wise, because the
1490 * cost of the large number of page protect
1491 * operations would be higher than the value
1492 * of doing the operation.
1493 */
1494 pmap_remove_all(m);
1495 vm_page_deactivate(m);
1496 } else {
1497 m->act_count -= min(m->act_count, ACT_DECLINE);
1498 vm_page_requeue(m);
1499 }
1500 }
1501 vm_page_unlock(m);
1502 VM_OBJECT_UNLOCK(object);
1503 m = next;
1504 }
1505 vm_page_unlock_queues();
1506 }
1507
1508 /*
1509 * vm_pageout is the high level pageout daemon.
1510 */
1511 static void
1512 vm_pageout()
1513 {
1514 int error, pass;
1515
1516 /*
1517 * Initialize some paging parameters.
1518 */
1519 cnt.v_interrupt_free_min = 2;
1520 if (cnt.v_page_count < 2000)
1521 vm_pageout_page_count = 8;
1522
1523 /*
1524 * v_free_reserved needs to include enough for the largest
1525 * swap pager structures plus enough for any pv_entry structs
1526 * when paging.
1527 */
1528 if (cnt.v_page_count > 1024)
1529 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200;
1530 else
1531 cnt.v_free_min = 4;
1532 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE +
1533 cnt.v_interrupt_free_min;
1534 cnt.v_free_reserved = vm_pageout_page_count +
1535 cnt.v_pageout_free_min + (cnt.v_page_count / 768);
1536 cnt.v_free_severe = cnt.v_free_min / 2;
1537 cnt.v_free_min += cnt.v_free_reserved;
1538 cnt.v_free_severe += cnt.v_free_reserved;
1539
1540 /*
1541 * v_free_target and v_cache_min control pageout hysteresis. Note
1542 * that these are more a measure of the VM cache queue hysteresis
1543 * then the VM free queue. Specifically, v_free_target is the
1544 * high water mark (free+cache pages).
1545 *
1546 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the
1547 * low water mark, while v_free_min is the stop. v_cache_min must
1548 * be big enough to handle memory needs while the pageout daemon
1549 * is signalled and run to free more pages.
1550 */
1551 if (cnt.v_free_count > 6144)
1552 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved;
1553 else
1554 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved;
1555
1556 if (cnt.v_free_count > 2048) {
1557 cnt.v_cache_min = cnt.v_free_target;
1558 cnt.v_cache_max = 2 * cnt.v_cache_min;
1559 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2;
1560 } else {
1561 cnt.v_cache_min = 0;
1562 cnt.v_cache_max = 0;
1563 cnt.v_inactive_target = cnt.v_free_count / 4;
1564 }
1565 if (cnt.v_inactive_target > cnt.v_free_count / 3)
1566 cnt.v_inactive_target = cnt.v_free_count / 3;
1567
1568 /* XXX does not really belong here */
1569 if (vm_page_max_wired == 0)
1570 vm_page_max_wired = cnt.v_free_count / 3;
1571
1572 if (vm_pageout_stats_max == 0)
1573 vm_pageout_stats_max = cnt.v_free_target;
1574
1575 /*
1576 * Set interval in seconds for stats scan.
1577 */
1578 if (vm_pageout_stats_interval == 0)
1579 vm_pageout_stats_interval = 5;
1580 if (vm_pageout_full_stats_interval == 0)
1581 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4;
1582
1583 swap_pager_swap_init();
1584 pass = 0;
1585 /*
1586 * The pageout daemon is never done, so loop forever.
1587 */
1588 while (TRUE) {
1589 /*
1590 * If we have enough free memory, wakeup waiters. Do
1591 * not clear vm_pages_needed until we reach our target,
1592 * otherwise we may be woken up over and over again and
1593 * waste a lot of cpu.
1594 */
1595 mtx_lock(&vm_page_queue_free_mtx);
1596 if (vm_pages_needed && !vm_page_count_min()) {
1597 if (!vm_paging_needed())
1598 vm_pages_needed = 0;
1599 wakeup(&cnt.v_free_count);
1600 }
1601 if (vm_pages_needed) {
1602 /*
1603 * Still not done, take a second pass without waiting
1604 * (unlimited dirty cleaning), otherwise sleep a bit
1605 * and try again.
1606 */
1607 ++pass;
1608 if (pass > 1)
1609 msleep(&vm_pages_needed,
1610 &vm_page_queue_free_mtx, PVM, "psleep",
1611 hz / 2);
1612 } else {
1613 /*
1614 * Good enough, sleep & handle stats. Prime the pass
1615 * for the next run.
1616 */
1617 if (pass > 1)
1618 pass = 1;
1619 else
1620 pass = 0;
1621 error = msleep(&vm_pages_needed,
1622 &vm_page_queue_free_mtx, PVM, "psleep",
1623 vm_pageout_stats_interval * hz);
1624 if (error && !vm_pages_needed) {
1625 mtx_unlock(&vm_page_queue_free_mtx);
1626 pass = 0;
1627 vm_pageout_page_stats();
1628 continue;
1629 }
1630 }
1631 if (vm_pages_needed)
1632 cnt.v_pdwakeups++;
1633 mtx_unlock(&vm_page_queue_free_mtx);
1634 vm_pageout_scan(pass);
1635 }
1636 }
1637
1638 /*
1639 * Unless the free page queue lock is held by the caller, this function
1640 * should be regarded as advisory. Specifically, the caller should
1641 * not msleep() on &cnt.v_free_count following this function unless
1642 * the free page queue lock is held until the msleep() is performed.
1643 */
1644 void
1645 pagedaemon_wakeup()
1646 {
1647
1648 if (!vm_pages_needed && curthread->td_proc != pageproc) {
1649 vm_pages_needed = 1;
1650 wakeup(&vm_pages_needed);
1651 }
1652 }
1653
1654 #if !defined(NO_SWAPPING)
1655 static void
1656 vm_req_vmdaemon(int req)
1657 {
1658 static int lastrun = 0;
1659
1660 mtx_lock(&vm_daemon_mtx);
1661 vm_pageout_req_swapout |= req;
1662 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
1663 wakeup(&vm_daemon_needed);
1664 lastrun = ticks;
1665 }
1666 mtx_unlock(&vm_daemon_mtx);
1667 }
1668
1669 static void
1670 vm_daemon()
1671 {
1672 struct rlimit rsslim;
1673 struct proc *p;
1674 struct thread *td;
1675 struct vmspace *vm;
1676 int breakout, swapout_flags, tryagain, attempts;
1677 #ifdef RACCT
1678 uint64_t rsize, ravailable;
1679 #endif
1680
1681 while (TRUE) {
1682 mtx_lock(&vm_daemon_mtx);
1683 #ifdef RACCT
1684 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", hz);
1685 #else
1686 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0);
1687 #endif
1688 swapout_flags = vm_pageout_req_swapout;
1689 vm_pageout_req_swapout = 0;
1690 mtx_unlock(&vm_daemon_mtx);
1691 if (swapout_flags)
1692 swapout_procs(swapout_flags);
1693
1694 /*
1695 * scan the processes for exceeding their rlimits or if
1696 * process is swapped out -- deactivate pages
1697 */
1698 tryagain = 0;
1699 attempts = 0;
1700 again:
1701 attempts++;
1702 sx_slock(&allproc_lock);
1703 FOREACH_PROC_IN_SYSTEM(p) {
1704 vm_pindex_t limit, size;
1705
1706 /*
1707 * if this is a system process or if we have already
1708 * looked at this process, skip it.
1709 */
1710 PROC_LOCK(p);
1711 if (p->p_state != PRS_NORMAL ||
1712 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) {
1713 PROC_UNLOCK(p);
1714 continue;
1715 }
1716 /*
1717 * if the process is in a non-running type state,
1718 * don't touch it.
1719 */
1720 breakout = 0;
1721 FOREACH_THREAD_IN_PROC(p, td) {
1722 thread_lock(td);
1723 if (!TD_ON_RUNQ(td) &&
1724 !TD_IS_RUNNING(td) &&
1725 !TD_IS_SLEEPING(td) &&
1726 !TD_IS_SUSPENDED(td)) {
1727 thread_unlock(td);
1728 breakout = 1;
1729 break;
1730 }
1731 thread_unlock(td);
1732 }
1733 if (breakout) {
1734 PROC_UNLOCK(p);
1735 continue;
1736 }
1737 /*
1738 * get a limit
1739 */
1740 lim_rlimit(p, RLIMIT_RSS, &rsslim);
1741 limit = OFF_TO_IDX(
1742 qmin(rsslim.rlim_cur, rsslim.rlim_max));
1743
1744 /*
1745 * let processes that are swapped out really be
1746 * swapped out set the limit to nothing (will force a
1747 * swap-out.)
1748 */
1749 if ((p->p_flag & P_INMEM) == 0)
1750 limit = 0; /* XXX */
1751 vm = vmspace_acquire_ref(p);
1752 PROC_UNLOCK(p);
1753 if (vm == NULL)
1754 continue;
1755
1756 size = vmspace_resident_count(vm);
1757 if (limit >= 0 && size >= limit) {
1758 vm_pageout_map_deactivate_pages(
1759 &vm->vm_map, limit);
1760 }
1761 #ifdef RACCT
1762 rsize = IDX_TO_OFF(size);
1763 PROC_LOCK(p);
1764 racct_set(p, RACCT_RSS, rsize);
1765 ravailable = racct_get_available(p, RACCT_RSS);
1766 PROC_UNLOCK(p);
1767 if (rsize > ravailable) {
1768 /*
1769 * Don't be overly aggressive; this might be
1770 * an innocent process, and the limit could've
1771 * been exceeded by some memory hog. Don't
1772 * try to deactivate more than 1/4th of process'
1773 * resident set size.
1774 */
1775 if (attempts <= 8) {
1776 if (ravailable < rsize - (rsize / 4))
1777 ravailable = rsize - (rsize / 4);
1778 }
1779 vm_pageout_map_deactivate_pages(
1780 &vm->vm_map, OFF_TO_IDX(ravailable));
1781 /* Update RSS usage after paging out. */
1782 size = vmspace_resident_count(vm);
1783 rsize = IDX_TO_OFF(size);
1784 PROC_LOCK(p);
1785 racct_set(p, RACCT_RSS, rsize);
1786 PROC_UNLOCK(p);
1787 if (rsize > ravailable)
1788 tryagain = 1;
1789 }
1790 #endif
1791 vmspace_free(vm);
1792 }
1793 sx_sunlock(&allproc_lock);
1794 if (tryagain != 0 && attempts <= 10)
1795 goto again;
1796 }
1797 }
1798 #endif /* !defined(NO_SWAPPING) */
Cache object: b307a8a066baab4c75505665c0f1a856
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