Initial import from FreeBSD RELENG_4:
[dragonfly.git] / sys / vm / vm_pageout.c
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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: src/sys/vm/vm_pageout.c,v 1.151.2.15 2002/12/29 18:21:04 dillon Exp $
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/proc.h>
80#include <sys/kthread.h>
81#include <sys/resourcevar.h>
82#include <sys/signalvar.h>
83#include <sys/vnode.h>
84#include <sys/vmmeter.h>
85#include <sys/sysctl.h>
86
87#include <vm/vm.h>
88#include <vm/vm_param.h>
89#include <sys/lock.h>
90#include <vm/vm_object.h>
91#include <vm/vm_page.h>
92#include <vm/vm_map.h>
93#include <vm/vm_pageout.h>
94#include <vm/vm_pager.h>
95#include <vm/swap_pager.h>
96#include <vm/vm_extern.h>
97
98/*
99 * System initialization
100 */
101
102/* the kernel process "vm_pageout"*/
103static void vm_pageout __P((void));
104static int vm_pageout_clean __P((vm_page_t));
105static void vm_pageout_scan __P((int pass));
106static int vm_pageout_free_page_calc __P((vm_size_t count));
107struct proc *pageproc;
108
109static struct kproc_desc page_kp = {
110 "pagedaemon",
111 vm_pageout,
112 &pageproc
113};
114SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp)
115
116#if !defined(NO_SWAPPING)
117/* the kernel process "vm_daemon"*/
118static void vm_daemon __P((void));
119static struct proc *vmproc;
120
121static struct kproc_desc vm_kp = {
122 "vmdaemon",
123 vm_daemon,
124 &vmproc
125};
126SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp)
127#endif
128
129
130int vm_pages_needed=0; /* Event on which pageout daemon sleeps */
131int vm_pageout_deficit=0; /* Estimated number of pages deficit */
132int vm_pageout_pages_needed=0; /* flag saying that the pageout daemon needs pages */
133
134#if !defined(NO_SWAPPING)
135static int vm_pageout_req_swapout; /* XXX */
136static int vm_daemon_needed;
137#endif
138extern int vm_swap_size;
139static int vm_max_launder = 32;
140static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0;
141static int vm_pageout_full_stats_interval = 0;
142static int vm_pageout_stats_free_max=0, vm_pageout_algorithm=0;
143static int defer_swap_pageouts=0;
144static int disable_swap_pageouts=0;
145
146#if defined(NO_SWAPPING)
147static int vm_swap_enabled=0;
148static int vm_swap_idle_enabled=0;
149#else
150static int vm_swap_enabled=1;
151static int vm_swap_idle_enabled=0;
152#endif
153
154SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm,
155 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt");
156
157SYSCTL_INT(_vm, OID_AUTO, max_launder,
158 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout");
159
160SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max,
161 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length");
162
163SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval,
164 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan");
165
166SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval,
167 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan");
168
169SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max,
170 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented");
171
172#if defined(NO_SWAPPING)
173SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
174 CTLFLAG_RD, &vm_swap_enabled, 0, "");
175SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
176 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "");
177#else
178SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
179 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout");
180SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
181 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
182#endif
183
184SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts,
185 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem");
186
187SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts,
188 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages");
189
190static int pageout_lock_miss;
191SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss,
192 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout");
193
194#define VM_PAGEOUT_PAGE_COUNT 16
195int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
196
197int vm_page_max_wired; /* XXX max # of wired pages system-wide */
198
199#if !defined(NO_SWAPPING)
200typedef void freeer_fcn_t __P((vm_map_t, vm_object_t, vm_pindex_t, int));
201static void vm_pageout_map_deactivate_pages __P((vm_map_t, vm_pindex_t));
202static freeer_fcn_t vm_pageout_object_deactivate_pages;
203static void vm_req_vmdaemon __P((void));
204#endif
205static void vm_pageout_page_stats(void);
206
207/*
208 * vm_pageout_clean:
209 *
210 * Clean the page and remove it from the laundry.
211 *
212 * We set the busy bit to cause potential page faults on this page to
213 * block. Note the careful timing, however, the busy bit isn't set till
214 * late and we cannot do anything that will mess with the page.
215 */
216
217static int
218vm_pageout_clean(m)
219 vm_page_t m;
220{
221 register vm_object_t object;
222 vm_page_t mc[2*vm_pageout_page_count];
223 int pageout_count;
224 int ib, is, page_base;
225 vm_pindex_t pindex = m->pindex;
226
227 object = m->object;
228
229 /*
230 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP
231 * with the new swapper, but we could have serious problems paging
232 * out other object types if there is insufficient memory.
233 *
234 * Unfortunately, checking free memory here is far too late, so the
235 * check has been moved up a procedural level.
236 */
237
238 /*
239 * Don't mess with the page if it's busy, held, or special
240 */
241 if ((m->hold_count != 0) ||
242 ((m->busy != 0) || (m->flags & (PG_BUSY|PG_UNMANAGED)))) {
243 return 0;
244 }
245
246 mc[vm_pageout_page_count] = m;
247 pageout_count = 1;
248 page_base = vm_pageout_page_count;
249 ib = 1;
250 is = 1;
251
252 /*
253 * Scan object for clusterable pages.
254 *
255 * We can cluster ONLY if: ->> the page is NOT
256 * clean, wired, busy, held, or mapped into a
257 * buffer, and one of the following:
258 * 1) The page is inactive, or a seldom used
259 * active page.
260 * -or-
261 * 2) we force the issue.
262 *
263 * During heavy mmap/modification loads the pageout
264 * daemon can really fragment the underlying file
265 * due to flushing pages out of order and not trying
266 * align the clusters (which leave sporatic out-of-order
267 * holes). To solve this problem we do the reverse scan
268 * first and attempt to align our cluster, then do a
269 * forward scan if room remains.
270 */
271
272more:
273 while (ib && pageout_count < vm_pageout_page_count) {
274 vm_page_t p;
275
276 if (ib > pindex) {
277 ib = 0;
278 break;
279 }
280
281 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) {
282 ib = 0;
283 break;
284 }
285 if (((p->queue - p->pc) == PQ_CACHE) ||
286 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) {
287 ib = 0;
288 break;
289 }
290 vm_page_test_dirty(p);
291 if ((p->dirty & p->valid) == 0 ||
292 p->queue != PQ_INACTIVE ||
293 p->wire_count != 0 || /* may be held by buf cache */
294 p->hold_count != 0) { /* may be undergoing I/O */
295 ib = 0;
296 break;
297 }
298 mc[--page_base] = p;
299 ++pageout_count;
300 ++ib;
301 /*
302 * alignment boundry, stop here and switch directions. Do
303 * not clear ib.
304 */
305 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0)
306 break;
307 }
308
309 while (pageout_count < vm_pageout_page_count &&
310 pindex + is < object->size) {
311 vm_page_t p;
312
313 if ((p = vm_page_lookup(object, pindex + is)) == NULL)
314 break;
315 if (((p->queue - p->pc) == PQ_CACHE) ||
316 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) {
317 break;
318 }
319 vm_page_test_dirty(p);
320 if ((p->dirty & p->valid) == 0 ||
321 p->queue != PQ_INACTIVE ||
322 p->wire_count != 0 || /* may be held by buf cache */
323 p->hold_count != 0) { /* may be undergoing I/O */
324 break;
325 }
326 mc[page_base + pageout_count] = p;
327 ++pageout_count;
328 ++is;
329 }
330
331 /*
332 * If we exhausted our forward scan, continue with the reverse scan
333 * when possible, even past a page boundry. This catches boundry
334 * conditions.
335 */
336 if (ib && pageout_count < vm_pageout_page_count)
337 goto more;
338
339 /*
340 * we allow reads during pageouts...
341 */
342 return vm_pageout_flush(&mc[page_base], pageout_count, 0);
343}
344
345/*
346 * vm_pageout_flush() - launder the given pages
347 *
348 * The given pages are laundered. Note that we setup for the start of
349 * I/O ( i.e. busy the page ), mark it read-only, and bump the object
350 * reference count all in here rather then in the parent. If we want
351 * the parent to do more sophisticated things we may have to change
352 * the ordering.
353 */
354
355int
356vm_pageout_flush(mc, count, flags)
357 vm_page_t *mc;
358 int count;
359 int flags;
360{
361 register vm_object_t object;
362 int pageout_status[count];
363 int numpagedout = 0;
364 int i;
365
366 /*
367 * Initiate I/O. Bump the vm_page_t->busy counter and
368 * mark the pages read-only.
369 *
370 * We do not have to fixup the clean/dirty bits here... we can
371 * allow the pager to do it after the I/O completes.
372 */
373
374 for (i = 0; i < count; i++) {
375 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count));
376 vm_page_io_start(mc[i]);
377 vm_page_protect(mc[i], VM_PROT_READ);
378 }
379
380 object = mc[0]->object;
381 vm_object_pip_add(object, count);
382
383 vm_pager_put_pages(object, mc, count,
384 (flags | ((object == kernel_object) ? VM_PAGER_PUT_SYNC : 0)),
385 pageout_status);
386
387 for (i = 0; i < count; i++) {
388 vm_page_t mt = mc[i];
389
390 switch (pageout_status[i]) {
391 case VM_PAGER_OK:
392 numpagedout++;
393 break;
394 case VM_PAGER_PEND:
395 numpagedout++;
396 break;
397 case VM_PAGER_BAD:
398 /*
399 * Page outside of range of object. Right now we
400 * essentially lose the changes by pretending it
401 * worked.
402 */
403 pmap_clear_modify(mt);
404 vm_page_undirty(mt);
405 break;
406 case VM_PAGER_ERROR:
407 case VM_PAGER_FAIL:
408 /*
409 * If page couldn't be paged out, then reactivate the
410 * page so it doesn't clog the inactive list. (We
411 * will try paging out it again later).
412 */
413 vm_page_activate(mt);
414 break;
415 case VM_PAGER_AGAIN:
416 break;
417 }
418
419 /*
420 * If the operation is still going, leave the page busy to
421 * block all other accesses. Also, leave the paging in
422 * progress indicator set so that we don't attempt an object
423 * collapse.
424 */
425 if (pageout_status[i] != VM_PAGER_PEND) {
426 vm_object_pip_wakeup(object);
427 vm_page_io_finish(mt);
428 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt))
429 vm_page_protect(mt, VM_PROT_READ);
430 }
431 }
432 return numpagedout;
433}
434
435#if !defined(NO_SWAPPING)
436/*
437 * vm_pageout_object_deactivate_pages
438 *
439 * deactivate enough pages to satisfy the inactive target
440 * requirements or if vm_page_proc_limit is set, then
441 * deactivate all of the pages in the object and its
442 * backing_objects.
443 *
444 * The object and map must be locked.
445 */
446static void
447vm_pageout_object_deactivate_pages(map, object, desired, map_remove_only)
448 vm_map_t map;
449 vm_object_t object;
450 vm_pindex_t desired;
451 int map_remove_only;
452{
453 register vm_page_t p, next;
454 int rcount;
455 int remove_mode;
456 int s;
457
458 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS)
459 return;
460
461 while (object) {
462 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
463 return;
464 if (object->paging_in_progress)
465 return;
466
467 remove_mode = map_remove_only;
468 if (object->shadow_count > 1)
469 remove_mode = 1;
470 /*
471 * scan the objects entire memory queue
472 */
473 rcount = object->resident_page_count;
474 p = TAILQ_FIRST(&object->memq);
475 while (p && (rcount-- > 0)) {
476 int actcount;
477 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
478 return;
479 next = TAILQ_NEXT(p, listq);
480 cnt.v_pdpages++;
481 if (p->wire_count != 0 ||
482 p->hold_count != 0 ||
483 p->busy != 0 ||
484 (p->flags & (PG_BUSY|PG_UNMANAGED)) ||
485 !pmap_page_exists_quick(vm_map_pmap(map), p)) {
486 p = next;
487 continue;
488 }
489
490 actcount = pmap_ts_referenced(p);
491 if (actcount) {
492 vm_page_flag_set(p, PG_REFERENCED);
493 } else if (p->flags & PG_REFERENCED) {
494 actcount = 1;
495 }
496
497 if ((p->queue != PQ_ACTIVE) &&
498 (p->flags & PG_REFERENCED)) {
499 vm_page_activate(p);
500 p->act_count += actcount;
501 vm_page_flag_clear(p, PG_REFERENCED);
502 } else if (p->queue == PQ_ACTIVE) {
503 if ((p->flags & PG_REFERENCED) == 0) {
504 p->act_count -= min(p->act_count, ACT_DECLINE);
505 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) {
506 vm_page_protect(p, VM_PROT_NONE);
507 vm_page_deactivate(p);
508 } else {
509 s = splvm();
510 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq);
511 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq);
512 splx(s);
513 }
514 } else {
515 vm_page_activate(p);
516 vm_page_flag_clear(p, PG_REFERENCED);
517 if (p->act_count < (ACT_MAX - ACT_ADVANCE))
518 p->act_count += ACT_ADVANCE;
519 s = splvm();
520 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq);
521 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq);
522 splx(s);
523 }
524 } else if (p->queue == PQ_INACTIVE) {
525 vm_page_protect(p, VM_PROT_NONE);
526 }
527 p = next;
528 }
529 object = object->backing_object;
530 }
531 return;
532}
533
534/*
535 * deactivate some number of pages in a map, try to do it fairly, but
536 * that is really hard to do.
537 */
538static void
539vm_pageout_map_deactivate_pages(map, desired)
540 vm_map_t map;
541 vm_pindex_t desired;
542{
543 vm_map_entry_t tmpe;
544 vm_object_t obj, bigobj;
545 int nothingwired;
546
547 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT, (void *)0, curproc)) {
548 return;
549 }
550
551 bigobj = NULL;
552 nothingwired = TRUE;
553
554 /*
555 * first, search out the biggest object, and try to free pages from
556 * that.
557 */
558 tmpe = map->header.next;
559 while (tmpe != &map->header) {
560 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
561 obj = tmpe->object.vm_object;
562 if ((obj != NULL) && (obj->shadow_count <= 1) &&
563 ((bigobj == NULL) ||
564 (bigobj->resident_page_count < obj->resident_page_count))) {
565 bigobj = obj;
566 }
567 }
568 if (tmpe->wired_count > 0)
569 nothingwired = FALSE;
570 tmpe = tmpe->next;
571 }
572
573 if (bigobj)
574 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0);
575
576 /*
577 * Next, hunt around for other pages to deactivate. We actually
578 * do this search sort of wrong -- .text first is not the best idea.
579 */
580 tmpe = map->header.next;
581 while (tmpe != &map->header) {
582 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
583 break;
584 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
585 obj = tmpe->object.vm_object;
586 if (obj)
587 vm_pageout_object_deactivate_pages(map, obj, desired, 0);
588 }
589 tmpe = tmpe->next;
590 };
591
592 /*
593 * Remove all mappings if a process is swapped out, this will free page
594 * table pages.
595 */
596 if (desired == 0 && nothingwired)
597 pmap_remove(vm_map_pmap(map),
598 VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS);
599 vm_map_unlock(map);
600 return;
601}
602#endif
603
604/*
605 * Don't try to be fancy - being fancy can lead to VOP_LOCK's and therefore
606 * to vnode deadlocks. We only do it for OBJT_DEFAULT and OBJT_SWAP objects
607 * which we know can be trivially freed.
608 */
609
610void
611vm_pageout_page_free(vm_page_t m) {
612 vm_object_t object = m->object;
613 int type = object->type;
614
615 if (type == OBJT_SWAP || type == OBJT_DEFAULT)
616 vm_object_reference(object);
617 vm_page_busy(m);
618 vm_page_protect(m, VM_PROT_NONE);
619 vm_page_free(m);
620 if (type == OBJT_SWAP || type == OBJT_DEFAULT)
621 vm_object_deallocate(object);
622}
623
624/*
625 * vm_pageout_scan does the dirty work for the pageout daemon.
626 */
627static void
628vm_pageout_scan(int pass)
629{
630 vm_page_t m, next;
631 struct vm_page marker;
632 int page_shortage, maxscan, pcount;
633 int addl_page_shortage, addl_page_shortage_init;
634 struct proc *p, *bigproc;
635 vm_offset_t size, bigsize;
636 vm_object_t object;
637 int actcount;
638 int vnodes_skipped = 0;
639 int maxlaunder;
640 int s;
641
642 /*
643 * Do whatever cleanup that the pmap code can.
644 */
645 pmap_collect();
646
647 addl_page_shortage_init = vm_pageout_deficit;
648 vm_pageout_deficit = 0;
649
650 /*
651 * Calculate the number of pages we want to either free or move
652 * to the cache.
653 */
654 page_shortage = vm_paging_target() + addl_page_shortage_init;
655
656 /*
657 * Initialize our marker
658 */
659 bzero(&marker, sizeof(marker));
660 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER;
661 marker.queue = PQ_INACTIVE;
662 marker.wire_count = 1;
663
664 /*
665 * Start scanning the inactive queue for pages we can move to the
666 * cache or free. The scan will stop when the target is reached or
667 * we have scanned the entire inactive queue. Note that m->act_count
668 * is not used to form decisions for the inactive queue, only for the
669 * active queue.
670 *
671 * maxlaunder limits the number of dirty pages we flush per scan.
672 * For most systems a smaller value (16 or 32) is more robust under
673 * extreme memory and disk pressure because any unnecessary writes
674 * to disk can result in extreme performance degredation. However,
675 * systems with excessive dirty pages (especially when MAP_NOSYNC is
676 * used) will die horribly with limited laundering. If the pageout
677 * daemon cannot clean enough pages in the first pass, we let it go
678 * all out in succeeding passes.
679 */
680 if ((maxlaunder = vm_max_launder) <= 1)
681 maxlaunder = 1;
682 if (pass)
683 maxlaunder = 10000;
684
685rescan0:
686 addl_page_shortage = addl_page_shortage_init;
687 maxscan = cnt.v_inactive_count;
688 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl);
689 m != NULL && maxscan-- > 0 && page_shortage > 0;
690 m = next) {
691
692 cnt.v_pdpages++;
693
694 if (m->queue != PQ_INACTIVE) {
695 goto rescan0;
696 }
697
698 next = TAILQ_NEXT(m, pageq);
699
700 /*
701 * skip marker pages
702 */
703 if (m->flags & PG_MARKER)
704 continue;
705
706 /*
707 * A held page may be undergoing I/O, so skip it.
708 */
709 if (m->hold_count) {
710 s = splvm();
711 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
712 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
713 splx(s);
714 addl_page_shortage++;
715 continue;
716 }
717 /*
718 * Dont mess with busy pages, keep in the front of the
719 * queue, most likely are being paged out.
720 */
721 if (m->busy || (m->flags & PG_BUSY)) {
722 addl_page_shortage++;
723 continue;
724 }
725
726 /*
727 * If the object is not being used, we ignore previous
728 * references.
729 */
730 if (m->object->ref_count == 0) {
731 vm_page_flag_clear(m, PG_REFERENCED);
732 pmap_clear_reference(m);
733
734 /*
735 * Otherwise, if the page has been referenced while in the
736 * inactive queue, we bump the "activation count" upwards,
737 * making it less likely that the page will be added back to
738 * the inactive queue prematurely again. Here we check the
739 * page tables (or emulated bits, if any), given the upper
740 * level VM system not knowing anything about existing
741 * references.
742 */
743 } else if (((m->flags & PG_REFERENCED) == 0) &&
744 (actcount = pmap_ts_referenced(m))) {
745 vm_page_activate(m);
746 m->act_count += (actcount + ACT_ADVANCE);
747 continue;
748 }
749
750 /*
751 * If the upper level VM system knows about any page
752 * references, we activate the page. We also set the
753 * "activation count" higher than normal so that we will less
754 * likely place pages back onto the inactive queue again.
755 */
756 if ((m->flags & PG_REFERENCED) != 0) {
757 vm_page_flag_clear(m, PG_REFERENCED);
758 actcount = pmap_ts_referenced(m);
759 vm_page_activate(m);
760 m->act_count += (actcount + ACT_ADVANCE + 1);
761 continue;
762 }
763
764 /*
765 * If the upper level VM system doesn't know anything about
766 * the page being dirty, we have to check for it again. As
767 * far as the VM code knows, any partially dirty pages are
768 * fully dirty.
769 */
770 if (m->dirty == 0) {
771 vm_page_test_dirty(m);
772 } else {
773 vm_page_dirty(m);
774 }
775
776 /*
777 * Invalid pages can be easily freed
778 */
779 if (m->valid == 0) {
780 vm_pageout_page_free(m);
781 cnt.v_dfree++;
782 --page_shortage;
783
784 /*
785 * Clean pages can be placed onto the cache queue. This
786 * effectively frees them.
787 */
788 } else if (m->dirty == 0) {
789 /*
790 * Clean pages can be immediately freed to the cache.
791 */
792 vm_page_cache(m);
793 --page_shortage;
794 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) {
795 /*
796 * Dirty pages need to be paged out, but flushing
797 * a page is extremely expensive verses freeing
798 * a clean page. Rather then artificially limiting
799 * the number of pages we can flush, we instead give
800 * dirty pages extra priority on the inactive queue
801 * by forcing them to be cycled through the queue
802 * twice before being flushed, after which the
803 * (now clean) page will cycle through once more
804 * before being freed. This significantly extends
805 * the thrash point for a heavily loaded machine.
806 */
807 s = splvm();
808 vm_page_flag_set(m, PG_WINATCFLS);
809 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
810 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
811 splx(s);
812 } else if (maxlaunder > 0) {
813 /*
814 * We always want to try to flush some dirty pages if
815 * we encounter them, to keep the system stable.
816 * Normally this number is small, but under extreme
817 * pressure where there are insufficient clean pages
818 * on the inactive queue, we may have to go all out.
819 */
820 int swap_pageouts_ok;
821 struct vnode *vp = NULL;
822
823 object = m->object;
824
825 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) {
826 swap_pageouts_ok = 1;
827 } else {
828 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts);
829 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts &&
830 vm_page_count_min());
831
832 }
833
834 /*
835 * We don't bother paging objects that are "dead".
836 * Those objects are in a "rundown" state.
837 */
838 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
839 s = splvm();
840 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
841 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
842 splx(s);
843 continue;
844 }
845
846 /*
847 * The object is already known NOT to be dead. It
848 * is possible for the vget() to block the whole
849 * pageout daemon, but the new low-memory handling
850 * code should prevent it.
851 *
852 * The previous code skipped locked vnodes and, worse,
853 * reordered pages in the queue. This results in
854 * completely non-deterministic operation because,
855 * quite often, a vm_fault has initiated an I/O and
856 * is holding a locked vnode at just the point where
857 * the pageout daemon is woken up.
858 *
859 * We can't wait forever for the vnode lock, we might
860 * deadlock due to a vn_read() getting stuck in
861 * vm_wait while holding this vnode. We skip the
862 * vnode if we can't get it in a reasonable amount
863 * of time.
864 */
865
866 if (object->type == OBJT_VNODE) {
867 vp = object->handle;
868
869 if (vget(vp, LK_EXCLUSIVE|LK_NOOBJ|LK_TIMELOCK, curproc)) {
870 ++pageout_lock_miss;
871 if (object->flags & OBJ_MIGHTBEDIRTY)
872 vnodes_skipped++;
873 continue;
874 }
875
876 /*
877 * The page might have been moved to another
878 * queue during potential blocking in vget()
879 * above. The page might have been freed and
880 * reused for another vnode. The object might
881 * have been reused for another vnode.
882 */
883 if (m->queue != PQ_INACTIVE ||
884 m->object != object ||
885 object->handle != vp) {
886 if (object->flags & OBJ_MIGHTBEDIRTY)
887 vnodes_skipped++;
888 vput(vp);
889 continue;
890 }
891
892 /*
893 * The page may have been busied during the
894 * blocking in vput(); We don't move the
895 * page back onto the end of the queue so that
896 * statistics are more correct if we don't.
897 */
898 if (m->busy || (m->flags & PG_BUSY)) {
899 vput(vp);
900 continue;
901 }
902
903 /*
904 * If the page has become held it might
905 * be undergoing I/O, so skip it
906 */
907 if (m->hold_count) {
908 s = splvm();
909 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
910 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
911 splx(s);
912 if (object->flags & OBJ_MIGHTBEDIRTY)
913 vnodes_skipped++;
914 vput(vp);
915 continue;
916 }
917 }
918
919 /*
920 * If a page is dirty, then it is either being washed
921 * (but not yet cleaned) or it is still in the
922 * laundry. If it is still in the laundry, then we
923 * start the cleaning operation.
924 *
925 * This operation may cluster, invalidating the 'next'
926 * pointer. To prevent an inordinate number of
927 * restarts we use our marker to remember our place.
928 *
929 * decrement page_shortage on success to account for
930 * the (future) cleaned page. Otherwise we could wind
931 * up laundering or cleaning too many pages.
932 */
933 s = splvm();
934 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq);
935 splx(s);
936 if (vm_pageout_clean(m) != 0) {
937 --page_shortage;
938 --maxlaunder;
939 }
940 s = splvm();
941 next = TAILQ_NEXT(&marker, pageq);
942 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq);
943 splx(s);
944 if (vp != NULL)
945 vput(vp);
946 }
947 }
948
949 /*
950 * Compute the number of pages we want to try to move from the
951 * active queue to the inactive queue.
952 */
953 page_shortage = vm_paging_target() +
954 cnt.v_inactive_target - cnt.v_inactive_count;
955 page_shortage += addl_page_shortage;
956
957 /*
958 * Scan the active queue for things we can deactivate. We nominally
959 * track the per-page activity counter and use it to locate
960 * deactivation candidates.
961 */
962
963 pcount = cnt.v_active_count;
964 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
965
966 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) {
967
968 /*
969 * This is a consistency check, and should likely be a panic
970 * or warning.
971 */
972 if (m->queue != PQ_ACTIVE) {
973 break;
974 }
975
976 next = TAILQ_NEXT(m, pageq);
977 /*
978 * Don't deactivate pages that are busy.
979 */
980 if ((m->busy != 0) ||
981 (m->flags & PG_BUSY) ||
982 (m->hold_count != 0)) {
983 s = splvm();
984 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
985 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
986 splx(s);
987 m = next;
988 continue;
989 }
990
991 /*
992 * The count for pagedaemon pages is done after checking the
993 * page for eligibility...
994 */
995 cnt.v_pdpages++;
996
997 /*
998 * Check to see "how much" the page has been used.
999 */
1000 actcount = 0;
1001 if (m->object->ref_count != 0) {
1002 if (m->flags & PG_REFERENCED) {
1003 actcount += 1;
1004 }
1005 actcount += pmap_ts_referenced(m);
1006 if (actcount) {
1007 m->act_count += ACT_ADVANCE + actcount;
1008 if (m->act_count > ACT_MAX)
1009 m->act_count = ACT_MAX;
1010 }
1011 }
1012
1013 /*
1014 * Since we have "tested" this bit, we need to clear it now.
1015 */
1016 vm_page_flag_clear(m, PG_REFERENCED);
1017
1018 /*
1019 * Only if an object is currently being used, do we use the
1020 * page activation count stats.
1021 */
1022 if (actcount && (m->object->ref_count != 0)) {
1023 s = splvm();
1024 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1025 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1026 splx(s);
1027 } else {
1028 m->act_count -= min(m->act_count, ACT_DECLINE);
1029 if (vm_pageout_algorithm ||
1030 m->object->ref_count == 0 ||
1031 m->act_count == 0) {
1032 page_shortage--;
1033 if (m->object->ref_count == 0) {
1034 vm_page_protect(m, VM_PROT_NONE);
1035 if (m->dirty == 0)
1036 vm_page_cache(m);
1037 else
1038 vm_page_deactivate(m);
1039 } else {
1040 vm_page_deactivate(m);
1041 }
1042 } else {
1043 s = splvm();
1044 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1045 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1046 splx(s);
1047 }
1048 }
1049 m = next;
1050 }
1051
1052 s = splvm();
1053
1054 /*
1055 * We try to maintain some *really* free pages, this allows interrupt
1056 * code to be guaranteed space. Since both cache and free queues
1057 * are considered basically 'free', moving pages from cache to free
1058 * does not effect other calculations.
1059 */
1060
1061 while (cnt.v_free_count < cnt.v_free_reserved) {
1062 static int cache_rover = 0;
1063 m = vm_page_list_find(PQ_CACHE, cache_rover, FALSE);
1064 if (!m)
1065 break;
1066 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) ||
1067 m->busy ||
1068 m->hold_count ||
1069 m->wire_count) {
1070#ifdef INVARIANTS
1071 printf("Warning: busy page %p found in cache\n", m);
1072#endif
1073 vm_page_deactivate(m);
1074 continue;
1075 }
1076 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK;
1077 vm_pageout_page_free(m);
1078 cnt.v_dfree++;
1079 }
1080 splx(s);
1081
1082#if !defined(NO_SWAPPING)
1083 /*
1084 * Idle process swapout -- run once per second.
1085 */
1086 if (vm_swap_idle_enabled) {
1087 static long lsec;
1088 if (time_second != lsec) {
1089 vm_pageout_req_swapout |= VM_SWAP_IDLE;
1090 vm_req_vmdaemon();
1091 lsec = time_second;
1092 }
1093 }
1094#endif
1095
1096 /*
1097 * If we didn't get enough free pages, and we have skipped a vnode
1098 * in a writeable object, wakeup the sync daemon. And kick swapout
1099 * if we did not get enough free pages.
1100 */
1101 if (vm_paging_target() > 0) {
1102 if (vnodes_skipped && vm_page_count_min())
1103 (void) speedup_syncer();
1104#if !defined(NO_SWAPPING)
1105 if (vm_swap_enabled && vm_page_count_target()) {
1106 vm_req_vmdaemon();
1107 vm_pageout_req_swapout |= VM_SWAP_NORMAL;
1108 }
1109#endif
1110 }
1111
1112 /*
1113 * If we are out of swap and were not able to reach our paging
1114 * target, kill the largest process.
1115 */
1116 if ((vm_swap_size < 64 && vm_page_count_min()) ||
1117 (swap_pager_full && vm_paging_target() > 0)) {
1118#if 0
1119 if ((vm_swap_size < 64 || swap_pager_full) && vm_page_count_min()) {
1120#endif
1121 bigproc = NULL;
1122 bigsize = 0;
1123 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
1124 /*
1125 * if this is a system process, skip it
1126 */
1127 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) ||
1128 ((p->p_pid < 48) && (vm_swap_size != 0))) {
1129 continue;
1130 }
1131 /*
1132 * if the process is in a non-running type state,
1133 * don't touch it.
1134 */
1135 if (p->p_stat != SRUN && p->p_stat != SSLEEP) {
1136 continue;
1137 }
1138 /*
1139 * get the process size
1140 */
1141 size = vmspace_resident_count(p->p_vmspace) +
1142 vmspace_swap_count(p->p_vmspace);
1143 /*
1144 * if the this process is bigger than the biggest one
1145 * remember it.
1146 */
1147 if (size > bigsize) {
1148 bigproc = p;
1149 bigsize = size;
1150 }
1151 }
1152 if (bigproc != NULL) {
1153 killproc(bigproc, "out of swap space");
1154 bigproc->p_estcpu = 0;
1155 bigproc->p_nice = PRIO_MIN;
1156 resetpriority(bigproc);
1157 wakeup(&cnt.v_free_count);
1158 }
1159 }
1160}
1161
1162/*
1163 * This routine tries to maintain the pseudo LRU active queue,
1164 * so that during long periods of time where there is no paging,
1165 * that some statistic accumulation still occurs. This code
1166 * helps the situation where paging just starts to occur.
1167 */
1168static void
1169vm_pageout_page_stats()
1170{
1171 int s;
1172 vm_page_t m,next;
1173 int pcount,tpcount; /* Number of pages to check */
1174 static int fullintervalcount = 0;
1175 int page_shortage;
1176 int s0;
1177
1178 page_shortage =
1179 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) -
1180 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count);
1181
1182 if (page_shortage <= 0)
1183 return;
1184
1185 s0 = splvm();
1186
1187 pcount = cnt.v_active_count;
1188 fullintervalcount += vm_pageout_stats_interval;
1189 if (fullintervalcount < vm_pageout_full_stats_interval) {
1190 tpcount = (vm_pageout_stats_max * cnt.v_active_count) / cnt.v_page_count;
1191 if (pcount > tpcount)
1192 pcount = tpcount;
1193 } else {
1194 fullintervalcount = 0;
1195 }
1196
1197 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1198 while ((m != NULL) && (pcount-- > 0)) {
1199 int actcount;
1200
1201 if (m->queue != PQ_ACTIVE) {
1202 break;
1203 }
1204
1205 next = TAILQ_NEXT(m, pageq);
1206 /*
1207 * Don't deactivate pages that are busy.
1208 */
1209 if ((m->busy != 0) ||
1210 (m->flags & PG_BUSY) ||
1211 (m->hold_count != 0)) {
1212 s = splvm();
1213 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1214 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1215 splx(s);
1216 m = next;
1217 continue;
1218 }
1219
1220 actcount = 0;
1221 if (m->flags & PG_REFERENCED) {
1222 vm_page_flag_clear(m, PG_REFERENCED);
1223 actcount += 1;
1224 }
1225
1226 actcount += pmap_ts_referenced(m);
1227 if (actcount) {
1228 m->act_count += ACT_ADVANCE + actcount;
1229 if (m->act_count > ACT_MAX)
1230 m->act_count = ACT_MAX;
1231 s = splvm();
1232 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1233 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1234 splx(s);
1235 } else {
1236 if (m->act_count == 0) {
1237 /*
1238 * We turn off page access, so that we have
1239 * more accurate RSS stats. We don't do this
1240 * in the normal page deactivation when the
1241 * system is loaded VM wise, because the
1242 * cost of the large number of page protect
1243 * operations would be higher than the value
1244 * of doing the operation.
1245 */
1246 vm_page_protect(m, VM_PROT_NONE);
1247 vm_page_deactivate(m);
1248 } else {
1249 m->act_count -= min(m->act_count, ACT_DECLINE);
1250 s = splvm();
1251 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1252 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1253 splx(s);
1254 }
1255 }
1256
1257 m = next;
1258 }
1259 splx(s0);
1260}
1261
1262static int
1263vm_pageout_free_page_calc(count)
1264vm_size_t count;
1265{
1266 if (count < cnt.v_page_count)
1267 return 0;
1268 /*
1269 * free_reserved needs to include enough for the largest swap pager
1270 * structures plus enough for any pv_entry structs when paging.
1271 */
1272 if (cnt.v_page_count > 1024)
1273 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200;
1274 else
1275 cnt.v_free_min = 4;
1276 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE +
1277 cnt.v_interrupt_free_min;
1278 cnt.v_free_reserved = vm_pageout_page_count +
1279 cnt.v_pageout_free_min + (count / 768) + PQ_L2_SIZE;
1280 cnt.v_free_severe = cnt.v_free_min / 2;
1281 cnt.v_free_min += cnt.v_free_reserved;
1282 cnt.v_free_severe += cnt.v_free_reserved;
1283 return 1;
1284}
1285
1286
1287/*
1288 * vm_pageout is the high level pageout daemon.
1289 */
1290static void
1291vm_pageout()
1292{
1293 int pass;
1294
1295 /*
1296 * Initialize some paging parameters.
1297 */
1298
1299 cnt.v_interrupt_free_min = 2;
1300 if (cnt.v_page_count < 2000)
1301 vm_pageout_page_count = 8;
1302
1303 vm_pageout_free_page_calc(cnt.v_page_count);
1304 /*
1305 * v_free_target and v_cache_min control pageout hysteresis. Note
1306 * that these are more a measure of the VM cache queue hysteresis
1307 * then the VM free queue. Specifically, v_free_target is the
1308 * high water mark (free+cache pages).
1309 *
1310 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the
1311 * low water mark, while v_free_min is the stop. v_cache_min must
1312 * be big enough to handle memory needs while the pageout daemon
1313 * is signalled and run to free more pages.
1314 */
1315 if (cnt.v_free_count > 6144)
1316 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved;
1317 else
1318 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved;
1319
1320 if (cnt.v_free_count > 2048) {
1321 cnt.v_cache_min = cnt.v_free_target;
1322 cnt.v_cache_max = 2 * cnt.v_cache_min;
1323 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2;
1324 } else {
1325 cnt.v_cache_min = 0;
1326 cnt.v_cache_max = 0;
1327 cnt.v_inactive_target = cnt.v_free_count / 4;
1328 }
1329 if (cnt.v_inactive_target > cnt.v_free_count / 3)
1330 cnt.v_inactive_target = cnt.v_free_count / 3;
1331
1332 /* XXX does not really belong here */
1333 if (vm_page_max_wired == 0)
1334 vm_page_max_wired = cnt.v_free_count / 3;
1335
1336 if (vm_pageout_stats_max == 0)
1337 vm_pageout_stats_max = cnt.v_free_target;
1338
1339 /*
1340 * Set interval in seconds for stats scan.
1341 */
1342 if (vm_pageout_stats_interval == 0)
1343 vm_pageout_stats_interval = 5;
1344 if (vm_pageout_full_stats_interval == 0)
1345 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4;
1346
1347
1348 /*
1349 * Set maximum free per pass
1350 */
1351 if (vm_pageout_stats_free_max == 0)
1352 vm_pageout_stats_free_max = 5;
1353
1354 swap_pager_swap_init();
1355 pass = 0;
1356 /*
1357 * The pageout daemon is never done, so loop forever.
1358 */
1359 while (TRUE) {
1360 int error;
1361 int s = splvm();
1362
1363 /*
1364 * If we have enough free memory, wakeup waiters. Do
1365 * not clear vm_pages_needed until we reach our target,
1366 * otherwise we may be woken up over and over again and
1367 * waste a lot of cpu.
1368 */
1369 if (vm_pages_needed && !vm_page_count_min()) {
1370 if (vm_paging_needed() <= 0)
1371 vm_pages_needed = 0;
1372 wakeup(&cnt.v_free_count);
1373 }
1374 if (vm_pages_needed) {
1375 /*
1376 * Still not done, take a second pass without waiting
1377 * (unlimited dirty cleaning), otherwise sleep a bit
1378 * and try again.
1379 */
1380 ++pass;
1381 if (pass > 1)
1382 tsleep(&vm_pages_needed, PVM, "psleep", hz/2);
1383 } else {
1384 /*
1385 * Good enough, sleep & handle stats. Prime the pass
1386 * for the next run.
1387 */
1388 if (pass > 1)
1389 pass = 1;
1390 else
1391 pass = 0;
1392 error = tsleep(&vm_pages_needed,
1393 PVM, "psleep", vm_pageout_stats_interval * hz);
1394 if (error && !vm_pages_needed) {
1395 splx(s);
1396 pass = 0;
1397 vm_pageout_page_stats();
1398 continue;
1399 }
1400 }
1401
1402 if (vm_pages_needed)
1403 cnt.v_pdwakeups++;
1404 splx(s);
1405 vm_pageout_scan(pass);
1406 vm_pageout_deficit = 0;
1407 }
1408}
1409
1410void
1411pagedaemon_wakeup()
1412{
1413 if (!vm_pages_needed && curproc != pageproc) {
1414 vm_pages_needed++;
1415 wakeup(&vm_pages_needed);
1416 }
1417}
1418
1419#if !defined(NO_SWAPPING)
1420static void
1421vm_req_vmdaemon()
1422{
1423 static int lastrun = 0;
1424
1425 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
1426 wakeup(&vm_daemon_needed);
1427 lastrun = ticks;
1428 }
1429}
1430
1431static void
1432vm_daemon()
1433{
1434 struct proc *p;
1435
1436 while (TRUE) {
1437 tsleep(&vm_daemon_needed, PPAUSE, "psleep", 0);
1438 if (vm_pageout_req_swapout) {
1439 swapout_procs(vm_pageout_req_swapout);
1440 vm_pageout_req_swapout = 0;
1441 }
1442 /*
1443 * scan the processes for exceeding their rlimits or if
1444 * process is swapped out -- deactivate pages
1445 */
1446
1447 for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
1448 vm_pindex_t limit, size;
1449
1450 /*
1451 * if this is a system process or if we have already
1452 * looked at this process, skip it.
1453 */
1454 if (p->p_flag & (P_SYSTEM | P_WEXIT)) {
1455 continue;
1456 }
1457 /*
1458 * if the process is in a non-running type state,
1459 * don't touch it.
1460 */
1461 if (p->p_stat != SRUN && p->p_stat != SSLEEP) {
1462 continue;
1463 }
1464 /*
1465 * get a limit
1466 */
1467 limit = OFF_TO_IDX(
1468 qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur,
1469 p->p_rlimit[RLIMIT_RSS].rlim_max));
1470
1471 /*
1472 * let processes that are swapped out really be
1473 * swapped out set the limit to nothing (will force a
1474 * swap-out.)
1475 */
1476 if ((p->p_flag & P_INMEM) == 0)
1477 limit = 0; /* XXX */
1478
1479 size = vmspace_resident_count(p->p_vmspace);
1480 if (limit >= 0 && size >= limit) {
1481 vm_pageout_map_deactivate_pages(
1482 &p->p_vmspace->vm_map, limit);
1483 }
1484 }
1485 }
1486}
1487#endif