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 *
9 * This code is derived from software contributed to Berkeley by
10 * The Mach Operating System project at Carnegie-Mellon University.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 *
40 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
41 *
42 *
43 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
44 * All rights reserved.
45 *
46 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
47 *
48 * Permission to use, copy, modify and distribute this software and
49 * its documentation is hereby granted, provided that both the copyright
50 * notice and this permission notice appear in all copies of the
51 * software, derivative works or modified versions, and any portions
52 * thereof, and that both notices appear in supporting documentation.
53 *
54 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
55 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
56 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
57 *
58 * Carnegie Mellon requests users of this software to return to
59 *
60 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
61 * School of Computer Science
62 * Carnegie Mellon University
63 * Pittsburgh PA 15213-3890
64 *
65 * any improvements or extensions that they make and grant Carnegie the
66 * rights to redistribute these changes.
67 *
68 * $FreeBSD: releng/5.1/sys/vm/vm_pageout.c 115146 2003-05-19 00:51:07Z das $
69 */
70
71 /*
72 * The proverbial page-out daemon.
73 */
74
75 #include "opt_vm.h"
76 #include <sys/param.h>
77 #include <sys/systm.h>
78 #include <sys/kernel.h>
79 #include <sys/eventhandler.h>
80 #include <sys/lock.h>
81 #include <sys/mutex.h>
82 #include <sys/proc.h>
83 #include <sys/kthread.h>
84 #include <sys/ktr.h>
85 #include <sys/resourcevar.h>
86 #include <sys/sched.h>
87 #include <sys/signalvar.h>
88 #include <sys/vnode.h>
89 #include <sys/vmmeter.h>
90 #include <sys/sx.h>
91 #include <sys/sysctl.h>
92
93 #include <vm/vm.h>
94 #include <vm/vm_param.h>
95 #include <vm/vm_object.h>
96 #include <vm/vm_page.h>
97 #include <vm/vm_map.h>
98 #include <vm/vm_pageout.h>
99 #include <vm/vm_pager.h>
100 #include <vm/swap_pager.h>
101 #include <vm/vm_extern.h>
102 #include <vm/uma.h>
103
104 #include <machine/mutex.h>
105
106 /*
107 * System initialization
108 */
109
110 /* the kernel process "vm_pageout"*/
111 static void vm_pageout(void);
112 static int vm_pageout_clean(vm_page_t);
113 static void vm_pageout_page_free(vm_page_t);
114 static void vm_pageout_pmap_collect(void);
115 static void vm_pageout_scan(int pass);
116 static int vm_pageout_free_page_calc(vm_size_t count);
117 struct proc *pageproc;
118
119 static struct kproc_desc page_kp = {
120 "pagedaemon",
121 vm_pageout,
122 &pageproc
123 };
124 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp)
125
126 #if !defined(NO_SWAPPING)
127 /* the kernel process "vm_daemon"*/
128 static void vm_daemon(void);
129 static struct proc *vmproc;
130
131 static struct kproc_desc vm_kp = {
132 "vmdaemon",
133 vm_daemon,
134 &vmproc
135 };
136 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp)
137 #endif
138
139
140 int vm_pages_needed; /* Event on which pageout daemon sleeps */
141 int vm_pageout_deficit; /* Estimated number of pages deficit */
142 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */
143
144 #if !defined(NO_SWAPPING)
145 static int vm_pageout_req_swapout; /* XXX */
146 static int vm_daemon_needed;
147 #endif
148 static int vm_max_launder = 32;
149 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0;
150 static int vm_pageout_full_stats_interval = 0;
151 static int vm_pageout_stats_free_max=0, vm_pageout_algorithm=0;
152 static int defer_swap_pageouts=0;
153 static int disable_swap_pageouts=0;
154
155 #if defined(NO_SWAPPING)
156 static int vm_swap_enabled=0;
157 static int vm_swap_idle_enabled=0;
158 #else
159 static int vm_swap_enabled=1;
160 static int vm_swap_idle_enabled=0;
161 #endif
162
163 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm,
164 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt");
165
166 SYSCTL_INT(_vm, OID_AUTO, max_launder,
167 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout");
168
169 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max,
170 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length");
171
172 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval,
173 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan");
174
175 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval,
176 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan");
177
178 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max,
179 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented");
180
181 #if defined(NO_SWAPPING)
182 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
183 CTLFLAG_RD, &vm_swap_enabled, 0, "");
184 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
185 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "");
186 #else
187 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
188 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout");
189 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
190 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
191 #endif
192
193 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts,
194 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem");
195
196 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts,
197 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages");
198
199 static int pageout_lock_miss;
200 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss,
201 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout");
202
203 #define VM_PAGEOUT_PAGE_COUNT 16
204 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
205
206 int vm_page_max_wired; /* XXX max # of wired pages system-wide */
207
208 #if !defined(NO_SWAPPING)
209 typedef void freeer_fcn_t(vm_map_t, vm_object_t, vm_pindex_t);
210 static void vm_pageout_map_deactivate_pages(vm_map_t, vm_pindex_t);
211 static freeer_fcn_t vm_pageout_object_deactivate_pages;
212 static void vm_req_vmdaemon(void);
213 #endif
214 static void vm_pageout_page_stats(void);
215
216 /*
217 * vm_pageout_clean:
218 *
219 * Clean the page and remove it from the laundry.
220 *
221 * We set the busy bit to cause potential page faults on this page to
222 * block. Note the careful timing, however, the busy bit isn't set till
223 * late and we cannot do anything that will mess with the page.
224 */
225 static int
226 vm_pageout_clean(m)
227 vm_page_t m;
228 {
229 vm_object_t object;
230 vm_page_t mc[2*vm_pageout_page_count];
231 int pageout_count;
232 int ib, is, page_base;
233 vm_pindex_t pindex = m->pindex;
234
235 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
236
237 object = m->object;
238
239 /*
240 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP
241 * with the new swapper, but we could have serious problems paging
242 * out other object types if there is insufficient memory.
243 *
244 * Unfortunately, checking free memory here is far too late, so the
245 * check has been moved up a procedural level.
246 */
247
248 /*
249 * Don't mess with the page if it's busy, held, or special
250 */
251 if ((m->hold_count != 0) ||
252 ((m->busy != 0) || (m->flags & (PG_BUSY|PG_UNMANAGED)))) {
253 return 0;
254 }
255
256 mc[vm_pageout_page_count] = m;
257 pageout_count = 1;
258 page_base = vm_pageout_page_count;
259 ib = 1;
260 is = 1;
261
262 /*
263 * Scan object for clusterable pages.
264 *
265 * We can cluster ONLY if: ->> the page is NOT
266 * clean, wired, busy, held, or mapped into a
267 * buffer, and one of the following:
268 * 1) The page is inactive, or a seldom used
269 * active page.
270 * -or-
271 * 2) we force the issue.
272 *
273 * During heavy mmap/modification loads the pageout
274 * daemon can really fragment the underlying file
275 * due to flushing pages out of order and not trying
276 * align the clusters (which leave sporatic out-of-order
277 * holes). To solve this problem we do the reverse scan
278 * first and attempt to align our cluster, then do a
279 * forward scan if room remains.
280 */
281 more:
282 while (ib && pageout_count < vm_pageout_page_count) {
283 vm_page_t p;
284
285 if (ib > pindex) {
286 ib = 0;
287 break;
288 }
289
290 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) {
291 ib = 0;
292 break;
293 }
294 if (((p->queue - p->pc) == PQ_CACHE) ||
295 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) {
296 ib = 0;
297 break;
298 }
299 vm_page_test_dirty(p);
300 if ((p->dirty & p->valid) == 0 ||
301 p->queue != PQ_INACTIVE ||
302 p->wire_count != 0 || /* may be held by buf cache */
303 p->hold_count != 0) { /* may be undergoing I/O */
304 ib = 0;
305 break;
306 }
307 mc[--page_base] = p;
308 ++pageout_count;
309 ++ib;
310 /*
311 * alignment boundry, stop here and switch directions. Do
312 * not clear ib.
313 */
314 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0)
315 break;
316 }
317
318 while (pageout_count < vm_pageout_page_count &&
319 pindex + is < object->size) {
320 vm_page_t p;
321
322 if ((p = vm_page_lookup(object, pindex + is)) == NULL)
323 break;
324 if (((p->queue - p->pc) == PQ_CACHE) ||
325 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) {
326 break;
327 }
328 vm_page_test_dirty(p);
329 if ((p->dirty & p->valid) == 0 ||
330 p->queue != PQ_INACTIVE ||
331 p->wire_count != 0 || /* may be held by buf cache */
332 p->hold_count != 0) { /* may be undergoing I/O */
333 break;
334 }
335 mc[page_base + pageout_count] = p;
336 ++pageout_count;
337 ++is;
338 }
339
340 /*
341 * If we exhausted our forward scan, continue with the reverse scan
342 * when possible, even past a page boundry. This catches boundry
343 * conditions.
344 */
345 if (ib && pageout_count < vm_pageout_page_count)
346 goto more;
347
348 /*
349 * we allow reads during pageouts...
350 */
351 return vm_pageout_flush(&mc[page_base], pageout_count, 0, FALSE);
352 }
353
354 /*
355 * vm_pageout_flush() - launder the given pages
356 *
357 * The given pages are laundered. Note that we setup for the start of
358 * I/O ( i.e. busy the page ), mark it read-only, and bump the object
359 * reference count all in here rather then in the parent. If we want
360 * the parent to do more sophisticated things we may have to change
361 * the ordering.
362 */
363 int
364 vm_pageout_flush(mc, count, flags, is_object_locked)
365 vm_page_t *mc;
366 int count;
367 int flags;
368 int is_object_locked;
369 {
370 vm_object_t object;
371 int pageout_status[count];
372 int numpagedout = 0;
373 int i;
374
375 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
376 /*
377 * Initiate I/O. Bump the vm_page_t->busy counter and
378 * mark the pages read-only.
379 *
380 * We do not have to fixup the clean/dirty bits here... we can
381 * allow the pager to do it after the I/O completes.
382 *
383 * NOTE! mc[i]->dirty may be partial or fragmented due to an
384 * edge case with file fragments.
385 */
386 for (i = 0; i < count; i++) {
387 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count));
388 vm_page_io_start(mc[i]);
389 pmap_page_protect(mc[i], VM_PROT_READ);
390 }
391 object = mc[0]->object;
392 vm_page_unlock_queues();
393 if (!is_object_locked)
394 VM_OBJECT_LOCK(object);
395 vm_object_pip_add(object, count);
396 VM_OBJECT_UNLOCK(object);
397
398 vm_pager_put_pages(object, mc, count,
399 (flags | ((object == kernel_object) ? VM_PAGER_PUT_SYNC : 0)),
400 pageout_status);
401
402 VM_OBJECT_LOCK(object);
403 vm_page_lock_queues();
404 for (i = 0; i < count; i++) {
405 vm_page_t mt = mc[i];
406
407 switch (pageout_status[i]) {
408 case VM_PAGER_OK:
409 case VM_PAGER_PEND:
410 numpagedout++;
411 break;
412 case VM_PAGER_BAD:
413 /*
414 * Page outside of range of object. Right now we
415 * essentially lose the changes by pretending it
416 * worked.
417 */
418 pmap_clear_modify(mt);
419 vm_page_undirty(mt);
420 break;
421 case VM_PAGER_ERROR:
422 case VM_PAGER_FAIL:
423 /*
424 * If page couldn't be paged out, then reactivate the
425 * page so it doesn't clog the inactive list. (We
426 * will try paging out it again later).
427 */
428 vm_page_activate(mt);
429 break;
430 case VM_PAGER_AGAIN:
431 break;
432 }
433
434 /*
435 * If the operation is still going, leave the page busy to
436 * block all other accesses. Also, leave the paging in
437 * progress indicator set so that we don't attempt an object
438 * collapse.
439 */
440 if (pageout_status[i] != VM_PAGER_PEND) {
441 vm_object_pip_wakeup(object);
442 vm_page_io_finish(mt);
443 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt))
444 pmap_page_protect(mt, VM_PROT_READ);
445 }
446 }
447 if (!is_object_locked)
448 VM_OBJECT_UNLOCK(object);
449 return numpagedout;
450 }
451
452 #if !defined(NO_SWAPPING)
453 /*
454 * vm_pageout_object_deactivate_pages
455 *
456 * deactivate enough pages to satisfy the inactive target
457 * requirements or if vm_page_proc_limit is set, then
458 * deactivate all of the pages in the object and its
459 * backing_objects.
460 *
461 * The object and map must be locked.
462 */
463 static void
464 vm_pageout_object_deactivate_pages(map, object, desired)
465 vm_map_t map;
466 vm_object_t object;
467 vm_pindex_t desired;
468 {
469 vm_page_t p, next;
470 int actcount, rcount, remove_mode;
471
472 GIANT_REQUIRED;
473 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS)
474 return;
475
476 while (object) {
477 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
478 return;
479 if (object->paging_in_progress)
480 return;
481
482 remove_mode = 0;
483 if (object->shadow_count > 1)
484 remove_mode = 1;
485 /*
486 * scan the objects entire memory queue
487 */
488 rcount = object->resident_page_count;
489 p = TAILQ_FIRST(&object->memq);
490 vm_page_lock_queues();
491 while (p && (rcount-- > 0)) {
492 if (pmap_resident_count(map->pmap) <= desired) {
493 vm_page_unlock_queues();
494 return;
495 }
496 next = TAILQ_NEXT(p, listq);
497 cnt.v_pdpages++;
498 if (p->wire_count != 0 ||
499 p->hold_count != 0 ||
500 p->busy != 0 ||
501 (p->flags & (PG_BUSY|PG_UNMANAGED)) ||
502 !pmap_page_exists_quick(vm_map_pmap(map), p)) {
503 p = next;
504 continue;
505 }
506 actcount = pmap_ts_referenced(p);
507 if (actcount) {
508 vm_page_flag_set(p, PG_REFERENCED);
509 } else if (p->flags & PG_REFERENCED) {
510 actcount = 1;
511 }
512 if ((p->queue != PQ_ACTIVE) &&
513 (p->flags & PG_REFERENCED)) {
514 vm_page_activate(p);
515 p->act_count += actcount;
516 vm_page_flag_clear(p, PG_REFERENCED);
517 } else if (p->queue == PQ_ACTIVE) {
518 if ((p->flags & PG_REFERENCED) == 0) {
519 p->act_count -= min(p->act_count, ACT_DECLINE);
520 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) {
521 pmap_remove_all(p);
522 vm_page_deactivate(p);
523 } else {
524 vm_pageq_requeue(p);
525 }
526 } else {
527 vm_page_activate(p);
528 vm_page_flag_clear(p, PG_REFERENCED);
529 if (p->act_count < (ACT_MAX - ACT_ADVANCE))
530 p->act_count += ACT_ADVANCE;
531 vm_pageq_requeue(p);
532 }
533 } else if (p->queue == PQ_INACTIVE) {
534 pmap_remove_all(p);
535 }
536 p = next;
537 }
538 vm_page_unlock_queues();
539 object = object->backing_object;
540 }
541 }
542
543 /*
544 * deactivate some number of pages in a map, try to do it fairly, but
545 * that is really hard to do.
546 */
547 static void
548 vm_pageout_map_deactivate_pages(map, desired)
549 vm_map_t map;
550 vm_pindex_t desired;
551 {
552 vm_map_entry_t tmpe;
553 vm_object_t obj, bigobj;
554 int nothingwired;
555
556 GIANT_REQUIRED;
557 if (!vm_map_trylock(map))
558 return;
559
560 bigobj = NULL;
561 nothingwired = TRUE;
562
563 /*
564 * first, search out the biggest object, and try to free pages from
565 * that.
566 */
567 tmpe = map->header.next;
568 while (tmpe != &map->header) {
569 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
570 obj = tmpe->object.vm_object;
571 if ((obj != NULL) && (obj->shadow_count <= 1) &&
572 ((bigobj == NULL) ||
573 (bigobj->resident_page_count < obj->resident_page_count))) {
574 bigobj = obj;
575 }
576 }
577 if (tmpe->wired_count > 0)
578 nothingwired = FALSE;
579 tmpe = tmpe->next;
580 }
581
582 if (bigobj)
583 vm_pageout_object_deactivate_pages(map, bigobj, desired);
584
585 /*
586 * Next, hunt around for other pages to deactivate. We actually
587 * do this search sort of wrong -- .text first is not the best idea.
588 */
589 tmpe = map->header.next;
590 while (tmpe != &map->header) {
591 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
592 break;
593 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
594 obj = tmpe->object.vm_object;
595 if (obj)
596 vm_pageout_object_deactivate_pages(map, obj, desired);
597 }
598 tmpe = tmpe->next;
599 }
600
601 /*
602 * Remove all mappings if a process is swapped out, this will free page
603 * table pages.
604 */
605 if (desired == 0 && nothingwired) {
606 vm_page_lock_queues();
607 pmap_remove(vm_map_pmap(map), vm_map_min(map),
608 vm_map_max(map));
609 vm_page_unlock_queues();
610 }
611 vm_map_unlock(map);
612 }
613 #endif /* !defined(NO_SWAPPING) */
614
615 /*
616 * Warning! The page queue lock is released and reacquired.
617 */
618 static void
619 vm_pageout_page_free(vm_page_t m)
620 {
621 vm_object_t object = m->object;
622
623 mtx_assert(&vm_page_queue_mtx, MA_OWNED);
624 vm_page_busy(m);
625 vm_page_unlock_queues();
626 /*
627 * Avoid a lock order reversal. The page must be busy.
628 */
629 VM_OBJECT_LOCK(object);
630 vm_page_lock_queues();
631 pmap_remove_all(m);
632 vm_page_free(m);
633 VM_OBJECT_UNLOCK(object);
634 cnt.v_dfree++;
635 }
636
637 /*
638 * This routine is very drastic, but can save the system
639 * in a pinch.
640 */
641 static void
642 vm_pageout_pmap_collect(void)
643 {
644 int i;
645 vm_page_t m;
646 static int warningdone;
647
648 if (pmap_pagedaemon_waken == 0)
649 return;
650 if (warningdone < 5) {
651 printf("collecting pv entries -- suggest increasing PMAP_SHPGPERPROC\n");
652 warningdone++;
653 }
654 vm_page_lock_queues();
655 for (i = 0; i < vm_page_array_size; i++) {
656 m = &vm_page_array[i];
657 if (m->wire_count || m->hold_count || m->busy ||
658 (m->flags & (PG_BUSY | PG_UNMANAGED)))
659 continue;
660 pmap_remove_all(m);
661 }
662 vm_page_unlock_queues();
663 pmap_pagedaemon_waken = 0;
664 }
665
666 /*
667 * vm_pageout_scan does the dirty work for the pageout daemon.
668 */
669 static void
670 vm_pageout_scan(int pass)
671 {
672 vm_page_t m, next;
673 struct vm_page marker;
674 int save_page_shortage;
675 int save_inactive_count;
676 int page_shortage, maxscan, pcount;
677 int addl_page_shortage, addl_page_shortage_init;
678 struct proc *p, *bigproc;
679 vm_offset_t size, bigsize;
680 vm_object_t object;
681 int actcount;
682 int vnodes_skipped = 0;
683 int maxlaunder;
684 int s;
685 struct thread *td;
686
687 GIANT_REQUIRED;
688 /*
689 * Decrease registered cache sizes.
690 */
691 EVENTHANDLER_INVOKE(vm_lowmem, 0);
692 /*
693 * We do this explicitly after the caches have been drained above.
694 */
695 uma_reclaim();
696 /*
697 * Do whatever cleanup that the pmap code can.
698 */
699 vm_pageout_pmap_collect();
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 save_page_shortage = page_shortage;
709 save_inactive_count = cnt.v_inactive_count;
710
711 /*
712 * Initialize our marker
713 */
714 bzero(&marker, sizeof(marker));
715 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER;
716 marker.queue = PQ_INACTIVE;
717 marker.wire_count = 1;
718
719 /*
720 * Start scanning the inactive queue for pages we can move to the
721 * cache or free. The scan will stop when the target is reached or
722 * we have scanned the entire inactive queue. Note that m->act_count
723 * is not used to form decisions for the inactive queue, only for the
724 * active queue.
725 *
726 * maxlaunder limits the number of dirty pages we flush per scan.
727 * For most systems a smaller value (16 or 32) is more robust under
728 * extreme memory and disk pressure because any unnecessary writes
729 * to disk can result in extreme performance degredation. However,
730 * systems with excessive dirty pages (especially when MAP_NOSYNC is
731 * used) will die horribly with limited laundering. If the pageout
732 * daemon cannot clean enough pages in the first pass, we let it go
733 * all out in succeeding passes.
734 */
735 if ((maxlaunder = vm_max_launder) <= 1)
736 maxlaunder = 1;
737 if (pass)
738 maxlaunder = 10000;
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 (m->queue != PQ_INACTIVE) {
750 goto rescan0;
751 }
752
753 next = TAILQ_NEXT(m, pageq);
754
755 /*
756 * skip marker pages
757 */
758 if (m->flags & PG_MARKER)
759 continue;
760
761 /*
762 * A held page may be undergoing I/O, so skip it.
763 */
764 if (m->hold_count) {
765 vm_pageq_requeue(m);
766 addl_page_shortage++;
767 continue;
768 }
769 /*
770 * Don't mess with busy pages, keep in the front of the
771 * queue, most likely are being paged out.
772 */
773 if (m->busy || (m->flags & PG_BUSY)) {
774 addl_page_shortage++;
775 continue;
776 }
777
778 vm_page_lock_queues();
779 /*
780 * If the object is not being used, we ignore previous
781 * references.
782 */
783 if (m->object->ref_count == 0) {
784 vm_page_flag_clear(m, PG_REFERENCED);
785 pmap_clear_reference(m);
786
787 /*
788 * Otherwise, if the page has been referenced while in the
789 * inactive queue, we bump the "activation count" upwards,
790 * making it less likely that the page will be added back to
791 * the inactive queue prematurely again. Here we check the
792 * page tables (or emulated bits, if any), given the upper
793 * level VM system not knowing anything about existing
794 * references.
795 */
796 } else if (((m->flags & PG_REFERENCED) == 0) &&
797 (actcount = pmap_ts_referenced(m))) {
798 vm_page_activate(m);
799 vm_page_unlock_queues();
800 m->act_count += (actcount + ACT_ADVANCE);
801 continue;
802 }
803
804 /*
805 * If the upper level VM system knows about any page
806 * references, we activate the page. We also set the
807 * "activation count" higher than normal so that we will less
808 * likely place pages back onto the inactive queue again.
809 */
810 if ((m->flags & PG_REFERENCED) != 0) {
811 vm_page_flag_clear(m, PG_REFERENCED);
812 actcount = pmap_ts_referenced(m);
813 vm_page_activate(m);
814 vm_page_unlock_queues();
815 m->act_count += (actcount + ACT_ADVANCE + 1);
816 continue;
817 }
818
819 /*
820 * If the upper level VM system doesn't know anything about
821 * the page being dirty, we have to check for it again. As
822 * far as the VM code knows, any partially dirty pages are
823 * fully dirty.
824 */
825 if (m->dirty == 0) {
826 vm_page_test_dirty(m);
827 } else {
828 vm_page_dirty(m);
829 }
830 vm_page_unlock_queues();
831
832 /*
833 * Invalid pages can be easily freed
834 */
835 if (m->valid == 0) {
836 vm_page_lock_queues();
837 vm_pageout_page_free(m);
838 vm_page_unlock_queues();
839 --page_shortage;
840
841 /*
842 * Clean pages can be placed onto the cache queue. This
843 * effectively frees them.
844 */
845 } else if (m->dirty == 0) {
846 vm_page_lock_queues();
847 vm_page_cache(m);
848 vm_page_unlock_queues();
849 --page_shortage;
850 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) {
851 /*
852 * Dirty pages need to be paged out, but flushing
853 * a page is extremely expensive verses freeing
854 * a clean page. Rather then artificially limiting
855 * the number of pages we can flush, we instead give
856 * dirty pages extra priority on the inactive queue
857 * by forcing them to be cycled through the queue
858 * twice before being flushed, after which the
859 * (now clean) page will cycle through once more
860 * before being freed. This significantly extends
861 * the thrash point for a heavily loaded machine.
862 */
863 vm_page_lock_queues();
864 vm_page_flag_set(m, PG_WINATCFLS);
865 vm_pageq_requeue(m);
866 vm_page_unlock_queues();
867 } else if (maxlaunder > 0) {
868 /*
869 * We always want to try to flush some dirty pages if
870 * we encounter them, to keep the system stable.
871 * Normally this number is small, but under extreme
872 * pressure where there are insufficient clean pages
873 * on the inactive queue, we may have to go all out.
874 */
875 int swap_pageouts_ok;
876 struct vnode *vp = NULL;
877 struct mount *mp;
878
879 object = m->object;
880
881 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) {
882 swap_pageouts_ok = 1;
883 } else {
884 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts);
885 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts &&
886 vm_page_count_min());
887
888 }
889
890 /*
891 * We don't bother paging objects that are "dead".
892 * Those objects are in a "rundown" state.
893 */
894 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
895 vm_pageq_requeue(m);
896 continue;
897 }
898
899 /*
900 * The object is already known NOT to be dead. It
901 * is possible for the vget() to block the whole
902 * pageout daemon, but the new low-memory handling
903 * code should prevent it.
904 *
905 * The previous code skipped locked vnodes and, worse,
906 * reordered pages in the queue. This results in
907 * completely non-deterministic operation and, on a
908 * busy system, can lead to extremely non-optimal
909 * pageouts. For example, it can cause clean pages
910 * to be freed and dirty pages to be moved to the end
911 * of the queue. Since dirty pages are also moved to
912 * the end of the queue once-cleaned, this gives
913 * way too large a weighting to defering the freeing
914 * of dirty pages.
915 *
916 * We can't wait forever for the vnode lock, we might
917 * deadlock due to a vn_read() getting stuck in
918 * vm_wait while holding this vnode. We skip the
919 * vnode if we can't get it in a reasonable amount
920 * of time.
921 */
922 if (object->type == OBJT_VNODE) {
923 vp = object->handle;
924
925 mp = NULL;
926 if (vp->v_type == VREG)
927 vn_start_write(vp, &mp, V_NOWAIT);
928 if (vget(vp, LK_EXCLUSIVE|LK_TIMELOCK, curthread)) {
929 ++pageout_lock_miss;
930 vn_finished_write(mp);
931 if (object->flags & OBJ_MIGHTBEDIRTY)
932 vnodes_skipped++;
933 continue;
934 }
935
936 /*
937 * The page might have been moved to another
938 * queue during potential blocking in vget()
939 * above. The page might have been freed and
940 * reused for another vnode. The object might
941 * have been reused for another vnode.
942 */
943 if (m->queue != PQ_INACTIVE ||
944 m->object != object ||
945 object->handle != vp) {
946 if (object->flags & OBJ_MIGHTBEDIRTY)
947 vnodes_skipped++;
948 vput(vp);
949 vn_finished_write(mp);
950 continue;
951 }
952
953 /*
954 * The page may have been busied during the
955 * blocking in vput(); We don't move the
956 * page back onto the end of the queue so that
957 * statistics are more correct if we don't.
958 */
959 if (m->busy || (m->flags & PG_BUSY)) {
960 vput(vp);
961 vn_finished_write(mp);
962 continue;
963 }
964
965 /*
966 * If the page has become held it might
967 * be undergoing I/O, so skip it
968 */
969 if (m->hold_count) {
970 vm_pageq_requeue(m);
971 if (object->flags & OBJ_MIGHTBEDIRTY)
972 vnodes_skipped++;
973 vput(vp);
974 vn_finished_write(mp);
975 continue;
976 }
977 }
978
979 /*
980 * If a page is dirty, then it is either being washed
981 * (but not yet cleaned) or it is still in the
982 * laundry. If it is still in the laundry, then we
983 * start the cleaning operation.
984 *
985 * This operation may cluster, invalidating the 'next'
986 * pointer. To prevent an inordinate number of
987 * restarts we use our marker to remember our place.
988 *
989 * decrement page_shortage on success to account for
990 * the (future) cleaned page. Otherwise we could wind
991 * up laundering or cleaning too many pages.
992 */
993 vm_page_lock_queues();
994 s = splvm();
995 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq);
996 splx(s);
997 if (vm_pageout_clean(m) != 0) {
998 --page_shortage;
999 --maxlaunder;
1000 }
1001 s = splvm();
1002 next = TAILQ_NEXT(&marker, pageq);
1003 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq);
1004 splx(s);
1005 vm_page_unlock_queues();
1006 if (vp) {
1007 vput(vp);
1008 vn_finished_write(mp);
1009 }
1010 }
1011 }
1012
1013 /*
1014 * Compute the number of pages we want to try to move from the
1015 * active queue to the inactive queue.
1016 */
1017 page_shortage = vm_paging_target() +
1018 cnt.v_inactive_target - cnt.v_inactive_count;
1019 page_shortage += addl_page_shortage;
1020
1021 vm_page_lock_queues();
1022 /*
1023 * Scan the active queue for things we can deactivate. We nominally
1024 * track the per-page activity counter and use it to locate
1025 * deactivation candidates.
1026 */
1027 pcount = cnt.v_active_count;
1028 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1029
1030 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) {
1031
1032 /*
1033 * This is a consistency check, and should likely be a panic
1034 * or warning.
1035 */
1036 if (m->queue != PQ_ACTIVE) {
1037 break;
1038 }
1039
1040 next = TAILQ_NEXT(m, pageq);
1041 /*
1042 * Don't deactivate pages that are busy.
1043 */
1044 if ((m->busy != 0) ||
1045 (m->flags & PG_BUSY) ||
1046 (m->hold_count != 0)) {
1047 vm_pageq_requeue(m);
1048 m = next;
1049 continue;
1050 }
1051
1052 /*
1053 * The count for pagedaemon pages is done after checking the
1054 * page for eligibility...
1055 */
1056 cnt.v_pdpages++;
1057
1058 /*
1059 * Check to see "how much" the page has been used.
1060 */
1061 actcount = 0;
1062 if (m->object->ref_count != 0) {
1063 if (m->flags & PG_REFERENCED) {
1064 actcount += 1;
1065 }
1066 actcount += pmap_ts_referenced(m);
1067 if (actcount) {
1068 m->act_count += ACT_ADVANCE + actcount;
1069 if (m->act_count > ACT_MAX)
1070 m->act_count = ACT_MAX;
1071 }
1072 }
1073
1074 /*
1075 * Since we have "tested" this bit, we need to clear it now.
1076 */
1077 vm_page_flag_clear(m, PG_REFERENCED);
1078
1079 /*
1080 * Only if an object is currently being used, do we use the
1081 * page activation count stats.
1082 */
1083 if (actcount && (m->object->ref_count != 0)) {
1084 vm_pageq_requeue(m);
1085 } else {
1086 m->act_count -= min(m->act_count, ACT_DECLINE);
1087 if (vm_pageout_algorithm ||
1088 m->object->ref_count == 0 ||
1089 m->act_count == 0) {
1090 page_shortage--;
1091 if (m->object->ref_count == 0) {
1092 pmap_remove_all(m);
1093 if (m->dirty == 0)
1094 vm_page_cache(m);
1095 else
1096 vm_page_deactivate(m);
1097 } else {
1098 vm_page_deactivate(m);
1099 }
1100 } else {
1101 vm_pageq_requeue(m);
1102 }
1103 }
1104 m = next;
1105 }
1106 s = splvm();
1107
1108 /*
1109 * We try to maintain some *really* free pages, this allows interrupt
1110 * code to be guaranteed space. Since both cache and free queues
1111 * are considered basically 'free', moving pages from cache to free
1112 * does not effect other calculations.
1113 */
1114 while (cnt.v_free_count < cnt.v_free_reserved) {
1115 static int cache_rover = 0;
1116 m = vm_pageq_find(PQ_CACHE, cache_rover, FALSE);
1117 if (!m)
1118 break;
1119 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) ||
1120 m->busy ||
1121 m->hold_count ||
1122 m->wire_count) {
1123 #ifdef INVARIANTS
1124 printf("Warning: busy page %p found in cache\n", m);
1125 #endif
1126 vm_page_deactivate(m);
1127 continue;
1128 }
1129 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK;
1130 vm_pageout_page_free(m);
1131 }
1132 splx(s);
1133 vm_page_unlock_queues();
1134 #if !defined(NO_SWAPPING)
1135 /*
1136 * Idle process swapout -- run once per second.
1137 */
1138 if (vm_swap_idle_enabled) {
1139 static long lsec;
1140 if (time_second != lsec) {
1141 vm_pageout_req_swapout |= VM_SWAP_IDLE;
1142 vm_req_vmdaemon();
1143 lsec = time_second;
1144 }
1145 }
1146 #endif
1147
1148 /*
1149 * If we didn't get enough free pages, and we have skipped a vnode
1150 * in a writeable object, wakeup the sync daemon. And kick swapout
1151 * if we did not get enough free pages.
1152 */
1153 if (vm_paging_target() > 0) {
1154 if (vnodes_skipped && vm_page_count_min())
1155 (void) speedup_syncer();
1156 #if !defined(NO_SWAPPING)
1157 if (vm_swap_enabled && vm_page_count_target()) {
1158 vm_req_vmdaemon();
1159 vm_pageout_req_swapout |= VM_SWAP_NORMAL;
1160 }
1161 #endif
1162 }
1163
1164 /*
1165 * If we are critically low on one of RAM or swap and low on
1166 * the other, kill the largest process. However, we avoid
1167 * doing this on the first pass in order to give ourselves a
1168 * chance to flush out dirty vnode-backed pages and to allow
1169 * active pages to be moved to the inactive queue and reclaimed.
1170 *
1171 * We keep the process bigproc locked once we find it to keep anyone
1172 * from messing with it; however, there is a possibility of
1173 * deadlock if process B is bigproc and one of it's child processes
1174 * attempts to propagate a signal to B while we are waiting for A's
1175 * lock while walking this list. To avoid this, we don't block on
1176 * the process lock but just skip a process if it is already locked.
1177 */
1178 if (pass != 0 &&
1179 ((vm_swap_size < 64 && vm_page_count_min()) ||
1180 (swap_pager_full && vm_paging_target() > 0))) {
1181 bigproc = NULL;
1182 bigsize = 0;
1183 sx_slock(&allproc_lock);
1184 FOREACH_PROC_IN_SYSTEM(p) {
1185 int breakout;
1186 /*
1187 * If this process is already locked, skip it.
1188 */
1189 if (PROC_TRYLOCK(p) == 0)
1190 continue;
1191 /*
1192 * If this is a system or protected process, skip it.
1193 */
1194 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) ||
1195 (p->p_flag & P_PROTECTED) ||
1196 ((p->p_pid < 48) && (vm_swap_size != 0))) {
1197 PROC_UNLOCK(p);
1198 continue;
1199 }
1200 /*
1201 * if the process is in a non-running type state,
1202 * don't touch it. Check all the threads individually.
1203 */
1204 mtx_lock_spin(&sched_lock);
1205 breakout = 0;
1206 FOREACH_THREAD_IN_PROC(p, td) {
1207 if (!TD_ON_RUNQ(td) &&
1208 !TD_IS_RUNNING(td) &&
1209 !TD_IS_SLEEPING(td)) {
1210 breakout = 1;
1211 break;
1212 }
1213 }
1214 if (breakout) {
1215 mtx_unlock_spin(&sched_lock);
1216 PROC_UNLOCK(p);
1217 continue;
1218 }
1219 mtx_unlock_spin(&sched_lock);
1220 /*
1221 * get the process size
1222 */
1223 if (!vm_map_trylock_read(&p->p_vmspace->vm_map)) {
1224 PROC_UNLOCK(p);
1225 continue;
1226 }
1227 size = vmspace_swap_count(p->p_vmspace);
1228 vm_map_unlock_read(&p->p_vmspace->vm_map);
1229 size += vmspace_resident_count(p->p_vmspace);
1230 /*
1231 * if the this process is bigger than the biggest one
1232 * remember it.
1233 */
1234 if (size > bigsize) {
1235 if (bigproc != NULL)
1236 PROC_UNLOCK(bigproc);
1237 bigproc = p;
1238 bigsize = size;
1239 } else
1240 PROC_UNLOCK(p);
1241 }
1242 sx_sunlock(&allproc_lock);
1243 if (bigproc != NULL) {
1244 struct ksegrp *kg;
1245 killproc(bigproc, "out of swap space");
1246 mtx_lock_spin(&sched_lock);
1247 FOREACH_KSEGRP_IN_PROC(bigproc, kg) {
1248 sched_nice(kg, PRIO_MIN); /* XXXKSE ??? */
1249 }
1250 mtx_unlock_spin(&sched_lock);
1251 PROC_UNLOCK(bigproc);
1252 wakeup(&cnt.v_free_count);
1253 }
1254 }
1255 }
1256
1257 /*
1258 * This routine tries to maintain the pseudo LRU active queue,
1259 * so that during long periods of time where there is no paging,
1260 * that some statistic accumulation still occurs. This code
1261 * helps the situation where paging just starts to occur.
1262 */
1263 static void
1264 vm_pageout_page_stats()
1265 {
1266 vm_page_t m,next;
1267 int pcount,tpcount; /* Number of pages to check */
1268 static int fullintervalcount = 0;
1269 int page_shortage;
1270 int s0;
1271
1272 page_shortage =
1273 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) -
1274 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count);
1275
1276 if (page_shortage <= 0)
1277 return;
1278
1279 s0 = splvm();
1280 vm_page_lock_queues();
1281 pcount = cnt.v_active_count;
1282 fullintervalcount += vm_pageout_stats_interval;
1283 if (fullintervalcount < vm_pageout_full_stats_interval) {
1284 tpcount = (vm_pageout_stats_max * cnt.v_active_count) / cnt.v_page_count;
1285 if (pcount > tpcount)
1286 pcount = tpcount;
1287 } else {
1288 fullintervalcount = 0;
1289 }
1290
1291 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1292 while ((m != NULL) && (pcount-- > 0)) {
1293 int actcount;
1294
1295 if (m->queue != PQ_ACTIVE) {
1296 break;
1297 }
1298
1299 next = TAILQ_NEXT(m, pageq);
1300 /*
1301 * Don't deactivate pages that are busy.
1302 */
1303 if ((m->busy != 0) ||
1304 (m->flags & PG_BUSY) ||
1305 (m->hold_count != 0)) {
1306 vm_pageq_requeue(m);
1307 m = next;
1308 continue;
1309 }
1310
1311 actcount = 0;
1312 if (m->flags & PG_REFERENCED) {
1313 vm_page_flag_clear(m, PG_REFERENCED);
1314 actcount += 1;
1315 }
1316
1317 actcount += pmap_ts_referenced(m);
1318 if (actcount) {
1319 m->act_count += ACT_ADVANCE + actcount;
1320 if (m->act_count > ACT_MAX)
1321 m->act_count = ACT_MAX;
1322 vm_pageq_requeue(m);
1323 } else {
1324 if (m->act_count == 0) {
1325 /*
1326 * We turn off page access, so that we have
1327 * more accurate RSS stats. We don't do this
1328 * in the normal page deactivation when the
1329 * system is loaded VM wise, because the
1330 * cost of the large number of page protect
1331 * operations would be higher than the value
1332 * of doing the operation.
1333 */
1334 pmap_remove_all(m);
1335 vm_page_deactivate(m);
1336 } else {
1337 m->act_count -= min(m->act_count, ACT_DECLINE);
1338 vm_pageq_requeue(m);
1339 }
1340 }
1341
1342 m = next;
1343 }
1344 vm_page_unlock_queues();
1345 splx(s0);
1346 }
1347
1348 static int
1349 vm_pageout_free_page_calc(count)
1350 vm_size_t count;
1351 {
1352 if (count < cnt.v_page_count)
1353 return 0;
1354 /*
1355 * free_reserved needs to include enough for the largest swap pager
1356 * structures plus enough for any pv_entry structs when paging.
1357 */
1358 if (cnt.v_page_count > 1024)
1359 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200;
1360 else
1361 cnt.v_free_min = 4;
1362 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE +
1363 cnt.v_interrupt_free_min;
1364 cnt.v_free_reserved = vm_pageout_page_count +
1365 cnt.v_pageout_free_min + (count / 768) + PQ_L2_SIZE;
1366 cnt.v_free_severe = cnt.v_free_min / 2;
1367 cnt.v_free_min += cnt.v_free_reserved;
1368 cnt.v_free_severe += cnt.v_free_reserved;
1369 return 1;
1370 }
1371
1372 /*
1373 * vm_pageout is the high level pageout daemon.
1374 */
1375 static void
1376 vm_pageout()
1377 {
1378 int error, pass, s;
1379
1380 mtx_lock(&Giant);
1381
1382 /*
1383 * Initialize some paging parameters.
1384 */
1385 cnt.v_interrupt_free_min = 2;
1386 if (cnt.v_page_count < 2000)
1387 vm_pageout_page_count = 8;
1388
1389 vm_pageout_free_page_calc(cnt.v_page_count);
1390 /*
1391 * v_free_target and v_cache_min control pageout hysteresis. Note
1392 * that these are more a measure of the VM cache queue hysteresis
1393 * then the VM free queue. Specifically, v_free_target is the
1394 * high water mark (free+cache pages).
1395 *
1396 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the
1397 * low water mark, while v_free_min is the stop. v_cache_min must
1398 * be big enough to handle memory needs while the pageout daemon
1399 * is signalled and run to free more pages.
1400 */
1401 if (cnt.v_free_count > 6144)
1402 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved;
1403 else
1404 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved;
1405
1406 if (cnt.v_free_count > 2048) {
1407 cnt.v_cache_min = cnt.v_free_target;
1408 cnt.v_cache_max = 2 * cnt.v_cache_min;
1409 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2;
1410 } else {
1411 cnt.v_cache_min = 0;
1412 cnt.v_cache_max = 0;
1413 cnt.v_inactive_target = cnt.v_free_count / 4;
1414 }
1415 if (cnt.v_inactive_target > cnt.v_free_count / 3)
1416 cnt.v_inactive_target = cnt.v_free_count / 3;
1417
1418 /* XXX does not really belong here */
1419 if (vm_page_max_wired == 0)
1420 vm_page_max_wired = cnt.v_free_count / 3;
1421
1422 if (vm_pageout_stats_max == 0)
1423 vm_pageout_stats_max = cnt.v_free_target;
1424
1425 /*
1426 * Set interval in seconds for stats scan.
1427 */
1428 if (vm_pageout_stats_interval == 0)
1429 vm_pageout_stats_interval = 5;
1430 if (vm_pageout_full_stats_interval == 0)
1431 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4;
1432
1433 /*
1434 * Set maximum free per pass
1435 */
1436 if (vm_pageout_stats_free_max == 0)
1437 vm_pageout_stats_free_max = 5;
1438
1439 swap_pager_swap_init();
1440 pass = 0;
1441 /*
1442 * The pageout daemon is never done, so loop forever.
1443 */
1444 while (TRUE) {
1445 s = splvm();
1446 vm_page_lock_queues();
1447 /*
1448 * If we have enough free memory, wakeup waiters. Do
1449 * not clear vm_pages_needed until we reach our target,
1450 * otherwise we may be woken up over and over again and
1451 * waste a lot of cpu.
1452 */
1453 if (vm_pages_needed && !vm_page_count_min()) {
1454 if (!vm_paging_needed())
1455 vm_pages_needed = 0;
1456 wakeup(&cnt.v_free_count);
1457 }
1458 if (vm_pages_needed) {
1459 /*
1460 * Still not done, take a second pass without waiting
1461 * (unlimited dirty cleaning), otherwise sleep a bit
1462 * and try again.
1463 */
1464 ++pass;
1465 if (pass > 1)
1466 msleep(&vm_pages_needed, &vm_page_queue_mtx, PVM,
1467 "psleep", hz/2);
1468 } else {
1469 /*
1470 * Good enough, sleep & handle stats. Prime the pass
1471 * for the next run.
1472 */
1473 if (pass > 1)
1474 pass = 1;
1475 else
1476 pass = 0;
1477 error = msleep(&vm_pages_needed, &vm_page_queue_mtx, PVM,
1478 "psleep", vm_pageout_stats_interval * hz);
1479 if (error && !vm_pages_needed) {
1480 vm_page_unlock_queues();
1481 splx(s);
1482 pass = 0;
1483 vm_pageout_page_stats();
1484 continue;
1485 }
1486 }
1487 if (vm_pages_needed)
1488 cnt.v_pdwakeups++;
1489 vm_page_unlock_queues();
1490 splx(s);
1491 vm_pageout_scan(pass);
1492 }
1493 }
1494
1495 /*
1496 * Unless the page queue lock is held by the caller, this function
1497 * should be regarded as advisory. Specifically, the caller should
1498 * not msleep() on &cnt.v_free_count following this function unless
1499 * the page queue lock is held until the msleep() is performed.
1500 */
1501 void
1502 pagedaemon_wakeup()
1503 {
1504
1505 if (!vm_pages_needed && curthread->td_proc != pageproc) {
1506 vm_pages_needed = 1;
1507 wakeup(&vm_pages_needed);
1508 }
1509 }
1510
1511 #if !defined(NO_SWAPPING)
1512 static void
1513 vm_req_vmdaemon()
1514 {
1515 static int lastrun = 0;
1516
1517 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
1518 wakeup(&vm_daemon_needed);
1519 lastrun = ticks;
1520 }
1521 }
1522
1523 static void
1524 vm_daemon()
1525 {
1526 struct proc *p;
1527 int breakout;
1528 struct thread *td;
1529
1530 mtx_lock(&Giant);
1531 while (TRUE) {
1532 tsleep(&vm_daemon_needed, PPAUSE, "psleep", 0);
1533 if (vm_pageout_req_swapout) {
1534 swapout_procs(vm_pageout_req_swapout);
1535 vm_pageout_req_swapout = 0;
1536 }
1537 /*
1538 * scan the processes for exceeding their rlimits or if
1539 * process is swapped out -- deactivate pages
1540 */
1541 sx_slock(&allproc_lock);
1542 LIST_FOREACH(p, &allproc, p_list) {
1543 vm_pindex_t limit, size;
1544
1545 /*
1546 * if this is a system process or if we have already
1547 * looked at this process, skip it.
1548 */
1549 PROC_LOCK(p);
1550 if (p->p_flag & (P_SYSTEM | P_WEXIT)) {
1551 PROC_UNLOCK(p);
1552 continue;
1553 }
1554 /*
1555 * if the process is in a non-running type state,
1556 * don't touch it.
1557 */
1558 mtx_lock_spin(&sched_lock);
1559 breakout = 0;
1560 FOREACH_THREAD_IN_PROC(p, td) {
1561 if (!TD_ON_RUNQ(td) &&
1562 !TD_IS_RUNNING(td) &&
1563 !TD_IS_SLEEPING(td)) {
1564 breakout = 1;
1565 break;
1566 }
1567 }
1568 mtx_unlock_spin(&sched_lock);
1569 if (breakout) {
1570 PROC_UNLOCK(p);
1571 continue;
1572 }
1573 /*
1574 * get a limit
1575 */
1576 limit = OFF_TO_IDX(
1577 qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur,
1578 p->p_rlimit[RLIMIT_RSS].rlim_max));
1579
1580 /*
1581 * let processes that are swapped out really be
1582 * swapped out set the limit to nothing (will force a
1583 * swap-out.)
1584 */
1585 if ((p->p_sflag & PS_INMEM) == 0)
1586 limit = 0; /* XXX */
1587 PROC_UNLOCK(p);
1588
1589 size = vmspace_resident_count(p->p_vmspace);
1590 if (limit >= 0 && size >= limit) {
1591 vm_pageout_map_deactivate_pages(
1592 &p->p_vmspace->vm_map, limit);
1593 }
1594 }
1595 sx_sunlock(&allproc_lock);
1596 }
1597 }
1598 #endif /* !defined(NO_SWAPPING) */
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