2 * Copyright (c) 1991 Regents of the University of California.
4 * Copyright (c) 1994 John S. Dyson
6 * Copyright (c) 1994 David Greenman
8 * Copyright (c) 2005 Yahoo! Technologies Norway AS
11 * This code is derived from software contributed to Berkeley by
12 * The Mach Operating System project at Carnegie-Mellon University.
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
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.
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
42 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
45 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
46 * All rights reserved.
48 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
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.
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.
60 * Carnegie Mellon requests users of this software to return to
62 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
63 * School of Computer Science
64 * Carnegie Mellon University
65 * Pittsburgh PA 15213-3890
67 * any improvements or extensions that they make and grant Carnegie the
68 * rights to redistribute these changes.
72 * The proverbial page-out daemon.
75 #include <sys/cdefs.h>
76 __FBSDID("$FreeBSD$");
79 #include "opt_kdtrace.h"
80 #include <sys/param.h>
81 #include <sys/systm.h>
82 #include <sys/kernel.h>
83 #include <sys/eventhandler.h>
85 #include <sys/mutex.h>
87 #include <sys/kthread.h>
89 #include <sys/mount.h>
90 #include <sys/racct.h>
91 #include <sys/resourcevar.h>
92 #include <sys/sched.h>
94 #include <sys/signalvar.h>
97 #include <sys/vnode.h>
98 #include <sys/vmmeter.h>
99 #include <sys/rwlock.h>
101 #include <sys/sysctl.h>
104 #include <vm/vm_param.h>
105 #include <vm/vm_object.h>
106 #include <vm/vm_page.h>
107 #include <vm/vm_map.h>
108 #include <vm/vm_pageout.h>
109 #include <vm/vm_pager.h>
110 #include <vm/vm_phys.h>
111 #include <vm/swap_pager.h>
112 #include <vm/vm_extern.h>
116 * System initialization
119 /* the kernel process "vm_pageout"*/
120 static void vm_pageout(void);
121 static void vm_pageout_init(void);
122 static int vm_pageout_clean(vm_page_t m);
123 static int vm_pageout_cluster(vm_page_t m);
124 static void vm_pageout_scan(struct vm_domain *vmd, int pass);
125 static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass);
127 SYSINIT(pagedaemon_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, vm_pageout_init,
130 struct proc *pageproc;
132 static struct kproc_desc page_kp = {
137 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start,
140 SDT_PROVIDER_DEFINE(vm);
141 SDT_PROBE_DEFINE(vm, , , vm__lowmem_cache);
142 SDT_PROBE_DEFINE(vm, , , vm__lowmem_scan);
144 #if !defined(NO_SWAPPING)
145 /* the kernel process "vm_daemon"*/
146 static void vm_daemon(void);
147 static struct proc *vmproc;
149 static struct kproc_desc vm_kp = {
154 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp);
158 int vm_pages_needed; /* Event on which pageout daemon sleeps */
159 int vm_pageout_deficit; /* Estimated number of pages deficit */
160 int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */
161 int vm_pageout_wakeup_thresh;
163 #if !defined(NO_SWAPPING)
164 static int vm_pageout_req_swapout; /* XXX */
165 static int vm_daemon_needed;
166 static struct mtx vm_daemon_mtx;
167 /* Allow for use by vm_pageout before vm_daemon is initialized. */
168 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF);
170 static int vm_max_launder = 32;
171 static int vm_pageout_update_period;
172 static int defer_swap_pageouts;
173 static int disable_swap_pageouts;
174 static int lowmem_period = 10;
175 static time_t lowmem_uptime;
177 #if defined(NO_SWAPPING)
178 static int vm_swap_enabled = 0;
179 static int vm_swap_idle_enabled = 0;
181 static int vm_swap_enabled = 1;
182 static int vm_swap_idle_enabled = 0;
185 static int vm_panic_on_oom = 0;
187 SYSCTL_INT(_vm, OID_AUTO, panic_on_oom,
188 CTLFLAG_RWTUN, &vm_panic_on_oom, 0,
189 "panic on out of memory instead of killing the largest process");
191 SYSCTL_INT(_vm, OID_AUTO, pageout_wakeup_thresh,
192 CTLFLAG_RW, &vm_pageout_wakeup_thresh, 0,
193 "free page threshold for waking up the pageout daemon");
195 SYSCTL_INT(_vm, OID_AUTO, max_launder,
196 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout");
198 SYSCTL_INT(_vm, OID_AUTO, pageout_update_period,
199 CTLFLAG_RW, &vm_pageout_update_period, 0,
200 "Maximum active LRU update period");
202 SYSCTL_INT(_vm, OID_AUTO, lowmem_period, CTLFLAG_RW, &lowmem_period, 0,
203 "Low memory callback period");
205 #if defined(NO_SWAPPING)
206 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
207 CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout");
208 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
209 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
211 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
212 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout");
213 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
214 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
217 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts,
218 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem");
220 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts,
221 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages");
223 static int pageout_lock_miss;
224 SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss,
225 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout");
227 #define VM_PAGEOUT_PAGE_COUNT 16
228 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
230 int vm_page_max_wired; /* XXX max # of wired pages system-wide */
231 SYSCTL_INT(_vm, OID_AUTO, max_wired,
232 CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count");
234 static boolean_t vm_pageout_fallback_object_lock(vm_page_t, vm_page_t *);
235 static boolean_t vm_pageout_launder(struct vm_pagequeue *pq, int, vm_paddr_t,
237 #if !defined(NO_SWAPPING)
238 static void vm_pageout_map_deactivate_pages(vm_map_t, long);
239 static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long);
240 static void vm_req_vmdaemon(int req);
242 static boolean_t vm_pageout_page_lock(vm_page_t, vm_page_t *);
245 * Initialize a dummy page for marking the caller's place in the specified
246 * paging queue. In principle, this function only needs to set the flag
247 * PG_MARKER. Nonetheless, it wirte busies and initializes the hold count
248 * to one as safety precautions.
251 vm_pageout_init_marker(vm_page_t marker, u_short queue)
254 bzero(marker, sizeof(*marker));
255 marker->flags = PG_MARKER;
256 marker->busy_lock = VPB_SINGLE_EXCLUSIVER;
257 marker->queue = queue;
258 marker->hold_count = 1;
262 * vm_pageout_fallback_object_lock:
264 * Lock vm object currently associated with `m'. VM_OBJECT_TRYWLOCK is
265 * known to have failed and page queue must be either PQ_ACTIVE or
266 * PQ_INACTIVE. To avoid lock order violation, unlock the page queues
267 * while locking the vm object. Use marker page to detect page queue
268 * changes and maintain notion of next page on page queue. Return
269 * TRUE if no changes were detected, FALSE otherwise. vm object is
272 * This function depends on both the lock portion of struct vm_object
273 * and normal struct vm_page being type stable.
276 vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next)
278 struct vm_page marker;
279 struct vm_pagequeue *pq;
285 vm_pageout_init_marker(&marker, queue);
286 pq = vm_page_pagequeue(m);
289 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q);
290 vm_pagequeue_unlock(pq);
292 VM_OBJECT_WLOCK(object);
294 vm_pagequeue_lock(pq);
296 /* Page queue might have changed. */
297 *next = TAILQ_NEXT(&marker, plinks.q);
298 unchanged = (m->queue == queue &&
299 m->object == object &&
300 &marker == TAILQ_NEXT(m, plinks.q));
301 TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q);
306 * Lock the page while holding the page queue lock. Use marker page
307 * to detect page queue changes and maintain notion of next page on
308 * page queue. Return TRUE if no changes were detected, FALSE
309 * otherwise. The page is locked on return. The page queue lock might
310 * be dropped and reacquired.
312 * This function depends on normal struct vm_page being type stable.
315 vm_pageout_page_lock(vm_page_t m, vm_page_t *next)
317 struct vm_page marker;
318 struct vm_pagequeue *pq;
322 vm_page_lock_assert(m, MA_NOTOWNED);
323 if (vm_page_trylock(m))
327 vm_pageout_init_marker(&marker, queue);
328 pq = vm_page_pagequeue(m);
330 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q);
331 vm_pagequeue_unlock(pq);
333 vm_pagequeue_lock(pq);
335 /* Page queue might have changed. */
336 *next = TAILQ_NEXT(&marker, plinks.q);
337 unchanged = (m->queue == queue && &marker == TAILQ_NEXT(m, plinks.q));
338 TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q);
345 * Clean the page and remove it from the laundry.
347 * We set the busy bit to cause potential page faults on this page to
348 * block. Note the careful timing, however, the busy bit isn't set till
349 * late and we cannot do anything that will mess with the page.
352 vm_pageout_cluster(vm_page_t m)
355 vm_page_t mc[2*vm_pageout_page_count], pb, ps;
357 int ib, is, page_base;
358 vm_pindex_t pindex = m->pindex;
360 vm_page_lock_assert(m, MA_OWNED);
362 VM_OBJECT_ASSERT_WLOCKED(object);
365 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP
366 * with the new swapper, but we could have serious problems paging
367 * out other object types if there is insufficient memory.
369 * Unfortunately, checking free memory here is far too late, so the
370 * check has been moved up a procedural level.
374 * Can't clean the page if it's busy or held.
376 vm_page_assert_unbusied(m);
377 KASSERT(m->hold_count == 0, ("vm_pageout_clean: page %p is held", m));
380 mc[vm_pageout_page_count] = pb = ps = m;
382 page_base = vm_pageout_page_count;
387 * Scan object for clusterable pages.
389 * We can cluster ONLY if: ->> the page is NOT
390 * clean, wired, busy, held, or mapped into a
391 * buffer, and one of the following:
392 * 1) The page is inactive, or a seldom used
395 * 2) we force the issue.
397 * During heavy mmap/modification loads the pageout
398 * daemon can really fragment the underlying file
399 * due to flushing pages out of order and not trying
400 * align the clusters (which leave sporatic out-of-order
401 * holes). To solve this problem we do the reverse scan
402 * first and attempt to align our cluster, then do a
403 * forward scan if room remains.
406 while (ib && pageout_count < vm_pageout_page_count) {
414 if ((p = vm_page_prev(pb)) == NULL || vm_page_busied(p)) {
418 vm_page_test_dirty(p);
424 if (p->queue != PQ_INACTIVE ||
425 p->hold_count != 0) { /* may be undergoing I/O */
431 mc[--page_base] = pb = p;
435 * alignment boundry, stop here and switch directions. Do
438 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0)
442 while (pageout_count < vm_pageout_page_count &&
443 pindex + is < object->size) {
446 if ((p = vm_page_next(ps)) == NULL || vm_page_busied(p))
448 vm_page_test_dirty(p);
452 if (p->queue != PQ_INACTIVE ||
453 p->hold_count != 0) { /* may be undergoing I/O */
458 mc[page_base + pageout_count] = ps = p;
464 * If we exhausted our forward scan, continue with the reverse scan
465 * when possible, even past a page boundry. This catches boundry
468 if (ib && pageout_count < vm_pageout_page_count)
472 * we allow reads during pageouts...
474 return (vm_pageout_flush(&mc[page_base], pageout_count, 0, 0, NULL,
479 * vm_pageout_flush() - launder the given pages
481 * The given pages are laundered. Note that we setup for the start of
482 * I/O ( i.e. busy the page ), mark it read-only, and bump the object
483 * reference count all in here rather then in the parent. If we want
484 * the parent to do more sophisticated things we may have to change
487 * Returned runlen is the count of pages between mreq and first
488 * page after mreq with status VM_PAGER_AGAIN.
489 * *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL
490 * for any page in runlen set.
493 vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen,
496 vm_object_t object = mc[0]->object;
497 int pageout_status[count];
501 VM_OBJECT_ASSERT_WLOCKED(object);
504 * Initiate I/O. Bump the vm_page_t->busy counter and
505 * mark the pages read-only.
507 * We do not have to fixup the clean/dirty bits here... we can
508 * allow the pager to do it after the I/O completes.
510 * NOTE! mc[i]->dirty may be partial or fragmented due to an
511 * edge case with file fragments.
513 for (i = 0; i < count; i++) {
514 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL,
515 ("vm_pageout_flush: partially invalid page %p index %d/%d",
517 vm_page_sbusy(mc[i]);
518 pmap_remove_write(mc[i]);
520 vm_object_pip_add(object, count);
522 vm_pager_put_pages(object, mc, count, flags, pageout_status);
524 runlen = count - mreq;
527 for (i = 0; i < count; i++) {
528 vm_page_t mt = mc[i];
530 KASSERT(pageout_status[i] == VM_PAGER_PEND ||
531 !pmap_page_is_write_mapped(mt),
532 ("vm_pageout_flush: page %p is not write protected", mt));
533 switch (pageout_status[i]) {
540 * Page outside of range of object. Right now we
541 * essentially lose the changes by pretending it
549 * If page couldn't be paged out, then reactivate the
550 * page so it doesn't clog the inactive list. (We
551 * will try paging out it again later).
554 vm_page_activate(mt);
556 if (eio != NULL && i >= mreq && i - mreq < runlen)
560 if (i >= mreq && i - mreq < runlen)
566 * If the operation is still going, leave the page busy to
567 * block all other accesses. Also, leave the paging in
568 * progress indicator set so that we don't attempt an object
571 if (pageout_status[i] != VM_PAGER_PEND) {
572 vm_object_pip_wakeup(object);
578 return (numpagedout);
582 vm_pageout_launder(struct vm_pagequeue *pq, int tries, vm_paddr_t low,
589 vm_page_t m, m_tmp, next;
592 vm_pagequeue_lock(pq);
593 TAILQ_FOREACH_SAFE(m, &pq->pq_pl, plinks.q, next) {
594 if ((m->flags & PG_MARKER) != 0)
596 pa = VM_PAGE_TO_PHYS(m);
597 if (pa < low || pa + PAGE_SIZE > high)
599 if (!vm_pageout_page_lock(m, &next) || m->hold_count != 0) {
604 if ((!VM_OBJECT_TRYWLOCK(object) &&
605 (!vm_pageout_fallback_object_lock(m, &next) ||
606 m->hold_count != 0)) || vm_page_busied(m)) {
608 VM_OBJECT_WUNLOCK(object);
611 vm_page_test_dirty(m);
612 if (m->dirty == 0 && object->ref_count != 0)
616 if (tries == 0 || (object->flags & OBJ_DEAD) != 0) {
617 VM_OBJECT_WUNLOCK(object);
620 if (object->type == OBJT_VNODE) {
621 vm_pagequeue_unlock(pq);
623 vm_object_reference_locked(object);
624 VM_OBJECT_WUNLOCK(object);
625 (void)vn_start_write(vp, &mp, V_WAIT);
626 lockmode = MNT_SHARED_WRITES(vp->v_mount) ?
627 LK_SHARED : LK_EXCLUSIVE;
628 vn_lock(vp, lockmode | LK_RETRY);
629 VM_OBJECT_WLOCK(object);
630 vm_object_page_clean(object, 0, 0, OBJPC_SYNC);
631 VM_OBJECT_WUNLOCK(object);
633 vm_object_deallocate(object);
634 vn_finished_write(mp);
636 } else if (object->type == OBJT_SWAP ||
637 object->type == OBJT_DEFAULT) {
638 vm_pagequeue_unlock(pq);
640 vm_pageout_flush(&m_tmp, 1, VM_PAGER_PUT_SYNC,
642 VM_OBJECT_WUNLOCK(object);
647 * Dequeue here to prevent lock recursion in
650 vm_page_dequeue_locked(m);
654 VM_OBJECT_WUNLOCK(object);
656 vm_pagequeue_unlock(pq);
661 * Increase the number of cached pages. The specified value, "tries",
662 * determines which categories of pages are cached:
664 * 0: All clean, inactive pages within the specified physical address range
665 * are cached. Will not sleep.
666 * 1: The vm_lowmem handlers are called. All inactive pages within
667 * the specified physical address range are cached. May sleep.
668 * 2: The vm_lowmem handlers are called. All inactive and active pages
669 * within the specified physical address range are cached. May sleep.
672 vm_pageout_grow_cache(int tries, vm_paddr_t low, vm_paddr_t high)
674 int actl, actmax, inactl, inactmax, dom, initial_dom;
675 static int start_dom = 0;
679 * Decrease registered cache sizes. The vm_lowmem handlers
680 * may acquire locks and/or sleep, so they can only be invoked
681 * when "tries" is greater than zero.
683 SDT_PROBE0(vm, , , vm__lowmem_cache);
684 EVENTHANDLER_INVOKE(vm_lowmem, 0);
687 * We do this explicitly after the caches have been drained
694 * Make the next scan start on the next domain.
696 initial_dom = atomic_fetchadd_int(&start_dom, 1) % vm_ndomains;
699 inactmax = vm_cnt.v_inactive_count;
701 actmax = tries < 2 ? 0 : vm_cnt.v_active_count;
705 * Scan domains in round-robin order, first inactive queues,
706 * then active. Since domain usually owns large physically
707 * contiguous chunk of memory, it makes sense to completely
708 * exhaust one domain before switching to next, while growing
709 * the pool of contiguous physical pages.
711 * Do not even start launder a domain which cannot contain
712 * the specified address range, as indicated by segments
713 * constituting the domain.
716 if (inactl < inactmax) {
717 if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs,
719 vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_INACTIVE],
724 if (++dom == vm_ndomains)
726 if (dom != initial_dom)
730 if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs,
732 vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_ACTIVE],
737 if (++dom == vm_ndomains)
739 if (dom != initial_dom)
744 #if !defined(NO_SWAPPING)
746 * vm_pageout_object_deactivate_pages
748 * Deactivate enough pages to satisfy the inactive target
751 * The object and map must be locked.
754 vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object,
757 vm_object_t backing_object, object;
759 int act_delta, remove_mode;
761 VM_OBJECT_ASSERT_LOCKED(first_object);
762 if ((first_object->flags & OBJ_FICTITIOUS) != 0)
764 for (object = first_object;; object = backing_object) {
765 if (pmap_resident_count(pmap) <= desired)
767 VM_OBJECT_ASSERT_LOCKED(object);
768 if ((object->flags & OBJ_UNMANAGED) != 0 ||
769 object->paging_in_progress != 0)
773 if (object->shadow_count > 1)
776 * Scan the object's entire memory queue.
778 TAILQ_FOREACH(p, &object->memq, listq) {
779 if (pmap_resident_count(pmap) <= desired)
781 if (vm_page_busied(p))
783 PCPU_INC(cnt.v_pdpages);
785 if (p->wire_count != 0 || p->hold_count != 0 ||
786 !pmap_page_exists_quick(pmap, p)) {
790 act_delta = pmap_ts_referenced(p);
791 if ((p->aflags & PGA_REFERENCED) != 0) {
794 vm_page_aflag_clear(p, PGA_REFERENCED);
796 if (p->queue != PQ_ACTIVE && act_delta != 0) {
798 p->act_count += act_delta;
799 } else if (p->queue == PQ_ACTIVE) {
800 if (act_delta == 0) {
801 p->act_count -= min(p->act_count,
803 if (!remove_mode && p->act_count == 0) {
805 vm_page_deactivate(p);
810 if (p->act_count < ACT_MAX -
812 p->act_count += ACT_ADVANCE;
815 } else if (p->queue == PQ_INACTIVE)
819 if ((backing_object = object->backing_object) == NULL)
821 VM_OBJECT_RLOCK(backing_object);
822 if (object != first_object)
823 VM_OBJECT_RUNLOCK(object);
826 if (object != first_object)
827 VM_OBJECT_RUNLOCK(object);
831 * deactivate some number of pages in a map, try to do it fairly, but
832 * that is really hard to do.
835 vm_pageout_map_deactivate_pages(map, desired)
840 vm_object_t obj, bigobj;
843 if (!vm_map_trylock(map))
850 * first, search out the biggest object, and try to free pages from
853 tmpe = map->header.next;
854 while (tmpe != &map->header) {
855 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
856 obj = tmpe->object.vm_object;
857 if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) {
858 if (obj->shadow_count <= 1 &&
860 bigobj->resident_page_count < obj->resident_page_count)) {
862 VM_OBJECT_RUNLOCK(bigobj);
865 VM_OBJECT_RUNLOCK(obj);
868 if (tmpe->wired_count > 0)
869 nothingwired = FALSE;
873 if (bigobj != NULL) {
874 vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired);
875 VM_OBJECT_RUNLOCK(bigobj);
878 * Next, hunt around for other pages to deactivate. We actually
879 * do this search sort of wrong -- .text first is not the best idea.
881 tmpe = map->header.next;
882 while (tmpe != &map->header) {
883 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
885 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) {
886 obj = tmpe->object.vm_object;
888 VM_OBJECT_RLOCK(obj);
889 vm_pageout_object_deactivate_pages(map->pmap, obj, desired);
890 VM_OBJECT_RUNLOCK(obj);
897 * Remove all mappings if a process is swapped out, this will free page
900 if (desired == 0 && nothingwired) {
901 pmap_remove(vm_map_pmap(map), vm_map_min(map),
907 #endif /* !defined(NO_SWAPPING) */
910 * Attempt to acquire all of the necessary locks to launder a page and
911 * then call through the clustering layer to PUTPAGES. Wait a short
912 * time for a vnode lock.
914 * Requires the page and object lock on entry, releases both before return.
915 * Returns 0 on success and an errno otherwise.
918 vm_pageout_clean(vm_page_t m)
926 vm_page_assert_locked(m);
928 VM_OBJECT_ASSERT_WLOCKED(object);
934 * The object is already known NOT to be dead. It
935 * is possible for the vget() to block the whole
936 * pageout daemon, but the new low-memory handling
937 * code should prevent it.
939 * We can't wait forever for the vnode lock, we might
940 * deadlock due to a vn_read() getting stuck in
941 * vm_wait while holding this vnode. We skip the
942 * vnode if we can't get it in a reasonable amount
945 if (object->type == OBJT_VNODE) {
948 if (vp->v_type == VREG &&
949 vn_start_write(vp, &mp, V_NOWAIT) != 0) {
955 ("vp %p with NULL v_mount", vp));
956 vm_object_reference_locked(object);
958 VM_OBJECT_WUNLOCK(object);
959 lockmode = MNT_SHARED_WRITES(vp->v_mount) ?
960 LK_SHARED : LK_EXCLUSIVE;
961 if (vget(vp, lockmode | LK_TIMELOCK, curthread)) {
966 VM_OBJECT_WLOCK(object);
969 * While the object and page were unlocked, the page
971 * (1) moved to a different queue,
972 * (2) reallocated to a different object,
973 * (3) reallocated to a different offset, or
976 if (m->queue != PQ_INACTIVE || m->object != object ||
977 m->pindex != pindex || m->dirty == 0) {
984 * The page may have been busied or held while the object
985 * and page locks were released.
987 if (vm_page_busied(m) || m->hold_count != 0) {
995 * If a page is dirty, then it is either being washed
996 * (but not yet cleaned) or it is still in the
997 * laundry. If it is still in the laundry, then we
998 * start the cleaning operation.
1000 if (vm_pageout_cluster(m) == 0)
1004 VM_OBJECT_WUNLOCK(object);
1007 vm_page_lock_assert(m, MA_NOTOWNED);
1011 vm_object_deallocate(object);
1012 vn_finished_write(mp);
1019 * vm_pageout_scan does the dirty work for the pageout daemon.
1021 * pass 0 - Update active LRU/deactivate pages
1022 * pass 1 - Move inactive to cache or free
1023 * pass 2 - Launder dirty pages
1026 vm_pageout_scan(struct vm_domain *vmd, int pass)
1029 struct vm_pagequeue *pq;
1032 int act_delta, addl_page_shortage, deficit, maxscan, page_shortage;
1033 int vnodes_skipped = 0;
1034 int maxlaunder, scan_tick, scanned;
1035 boolean_t queues_locked;
1038 * If we need to reclaim memory ask kernel caches to return
1039 * some. We rate limit to avoid thrashing.
1041 if (vmd == &vm_dom[0] && pass > 0 &&
1042 (time_uptime - lowmem_uptime) >= lowmem_period) {
1044 * Decrease registered cache sizes.
1046 SDT_PROBE0(vm, , , vm__lowmem_scan);
1047 EVENTHANDLER_INVOKE(vm_lowmem, 0);
1049 * We do this explicitly after the caches have been
1053 lowmem_uptime = time_uptime;
1057 * The addl_page_shortage is the number of temporarily
1058 * stuck pages in the inactive queue. In other words, the
1059 * number of pages from the inactive count that should be
1060 * discounted in setting the target for the active queue scan.
1062 addl_page_shortage = 0;
1065 * Calculate the number of pages we want to either free or move
1069 deficit = atomic_readandclear_int(&vm_pageout_deficit);
1070 page_shortage = vm_paging_target() + deficit;
1072 page_shortage = deficit = 0;
1075 * maxlaunder limits the number of dirty pages we flush per scan.
1076 * For most systems a smaller value (16 or 32) is more robust under
1077 * extreme memory and disk pressure because any unnecessary writes
1078 * to disk can result in extreme performance degredation. However,
1079 * systems with excessive dirty pages (especially when MAP_NOSYNC is
1080 * used) will die horribly with limited laundering. If the pageout
1081 * daemon cannot clean enough pages in the first pass, we let it go
1082 * all out in succeeding passes.
1084 if ((maxlaunder = vm_max_launder) <= 1)
1090 * Start scanning the inactive queue for pages we can move to the
1091 * cache or free. The scan will stop when the target is reached or
1092 * we have scanned the entire inactive queue. Note that m->act_count
1093 * is not used to form decisions for the inactive queue, only for the
1096 pq = &vmd->vmd_pagequeues[PQ_INACTIVE];
1097 maxscan = pq->pq_cnt;
1098 vm_pagequeue_lock(pq);
1099 queues_locked = TRUE;
1100 for (m = TAILQ_FIRST(&pq->pq_pl);
1101 m != NULL && maxscan-- > 0 && page_shortage > 0;
1103 vm_pagequeue_assert_locked(pq);
1104 KASSERT(queues_locked, ("unlocked queues"));
1105 KASSERT(m->queue == PQ_INACTIVE, ("Inactive queue %p", m));
1107 PCPU_INC(cnt.v_pdpages);
1108 next = TAILQ_NEXT(m, plinks.q);
1113 if (m->flags & PG_MARKER)
1116 KASSERT((m->flags & PG_FICTITIOUS) == 0,
1117 ("Fictitious page %p cannot be in inactive queue", m));
1118 KASSERT((m->oflags & VPO_UNMANAGED) == 0,
1119 ("Unmanaged page %p cannot be in inactive queue", m));
1122 * The page or object lock acquisitions fail if the
1123 * page was removed from the queue or moved to a
1124 * different position within the queue. In either
1125 * case, addl_page_shortage should not be incremented.
1127 if (!vm_pageout_page_lock(m, &next)) {
1132 if (!VM_OBJECT_TRYWLOCK(object) &&
1133 !vm_pageout_fallback_object_lock(m, &next)) {
1135 VM_OBJECT_WUNLOCK(object);
1140 * Don't mess with busy pages, keep them at at the
1141 * front of the queue, most likely they are being
1142 * paged out. Increment addl_page_shortage for busy
1143 * pages, because they may leave the inactive queue
1144 * shortly after page scan is finished.
1146 if (vm_page_busied(m)) {
1148 VM_OBJECT_WUNLOCK(object);
1149 addl_page_shortage++;
1154 * We unlock the inactive page queue, invalidating the
1155 * 'next' pointer. Use our marker to remember our
1158 TAILQ_INSERT_AFTER(&pq->pq_pl, m, &vmd->vmd_marker, plinks.q);
1159 vm_pagequeue_unlock(pq);
1160 queues_locked = FALSE;
1163 * Invalid pages can be easily freed. They cannot be
1164 * mapped, vm_page_free() asserts this.
1166 if (m->valid == 0 && m->hold_count == 0) {
1168 PCPU_INC(cnt.v_dfree);
1174 * We bump the activation count if the page has been
1175 * referenced while in the inactive queue. This makes
1176 * it less likely that the page will be added back to the
1177 * inactive queue prematurely again. Here we check the
1178 * page tables (or emulated bits, if any), given the upper
1179 * level VM system not knowing anything about existing
1182 if ((m->aflags & PGA_REFERENCED) != 0) {
1183 vm_page_aflag_clear(m, PGA_REFERENCED);
1187 if (object->ref_count != 0) {
1188 act_delta += pmap_ts_referenced(m);
1190 KASSERT(!pmap_page_is_mapped(m),
1191 ("vm_pageout_scan: page %p is mapped", m));
1195 * If the upper level VM system knows about any page
1196 * references, we reactivate the page or requeue it.
1198 if (act_delta != 0) {
1199 if (object->ref_count != 0) {
1200 vm_page_activate(m);
1201 m->act_count += act_delta + ACT_ADVANCE;
1203 vm_pagequeue_lock(pq);
1204 queues_locked = TRUE;
1205 vm_page_requeue_locked(m);
1210 if (m->hold_count != 0) {
1212 * Held pages are essentially stuck in the
1213 * queue. So, they ought to be discounted
1214 * from the inactive count. See the
1215 * calculation of the page_shortage for the
1216 * loop over the active queue below.
1218 addl_page_shortage++;
1223 * If the page appears to be clean at the machine-independent
1224 * layer, then remove all of its mappings from the pmap in
1225 * anticipation of placing it onto the cache queue. If,
1226 * however, any of the page's mappings allow write access,
1227 * then the page may still be modified until the last of those
1228 * mappings are removed.
1230 if (object->ref_count != 0) {
1231 vm_page_test_dirty(m);
1236 if (m->dirty == 0) {
1238 * Clean pages can be freed.
1241 PCPU_INC(cnt.v_dfree);
1243 } else if ((m->flags & PG_WINATCFLS) == 0 && pass < 2) {
1245 * Dirty pages need to be paged out, but flushing
1246 * a page is extremely expensive versus freeing
1247 * a clean page. Rather then artificially limiting
1248 * the number of pages we can flush, we instead give
1249 * dirty pages extra priority on the inactive queue
1250 * by forcing them to be cycled through the queue
1251 * twice before being flushed, after which the
1252 * (now clean) page will cycle through once more
1253 * before being freed. This significantly extends
1254 * the thrash point for a heavily loaded machine.
1256 m->flags |= PG_WINATCFLS;
1257 vm_pagequeue_lock(pq);
1258 queues_locked = TRUE;
1259 vm_page_requeue_locked(m);
1260 } else if (maxlaunder > 0) {
1262 * We always want to try to flush some dirty pages if
1263 * we encounter them, to keep the system stable.
1264 * Normally this number is small, but under extreme
1265 * pressure where there are insufficient clean pages
1266 * on the inactive queue, we may have to go all out.
1268 int swap_pageouts_ok;
1271 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) {
1272 swap_pageouts_ok = 1;
1274 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts);
1275 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts &&
1276 vm_page_count_min());
1281 * We don't bother paging objects that are "dead".
1282 * Those objects are in a "rundown" state.
1284 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
1285 vm_pagequeue_lock(pq);
1287 VM_OBJECT_WUNLOCK(object);
1288 queues_locked = TRUE;
1289 vm_page_requeue_locked(m);
1292 error = vm_pageout_clean(m);
1294 * Decrement page_shortage on success to account for
1295 * the (future) cleaned page. Otherwise we could wind
1296 * up laundering or cleaning too many pages.
1301 } else if (error == EDEADLK) {
1302 pageout_lock_miss++;
1304 } else if (error == EBUSY) {
1305 addl_page_shortage++;
1307 vm_page_lock_assert(m, MA_NOTOWNED);
1312 VM_OBJECT_WUNLOCK(object);
1314 if (!queues_locked) {
1315 vm_pagequeue_lock(pq);
1316 queues_locked = TRUE;
1318 next = TAILQ_NEXT(&vmd->vmd_marker, plinks.q);
1319 TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_marker, plinks.q);
1321 vm_pagequeue_unlock(pq);
1323 #if !defined(NO_SWAPPING)
1325 * Wakeup the swapout daemon if we didn't cache or free the targeted
1328 if (vm_swap_enabled && page_shortage > 0)
1329 vm_req_vmdaemon(VM_SWAP_NORMAL);
1333 * Wakeup the sync daemon if we skipped a vnode in a writeable object
1334 * and we didn't cache or free enough pages.
1336 if (vnodes_skipped > 0 && page_shortage > vm_cnt.v_free_target -
1338 (void)speedup_syncer();
1341 * Compute the number of pages we want to try to move from the
1342 * active queue to the inactive queue.
1344 page_shortage = vm_cnt.v_inactive_target - vm_cnt.v_inactive_count +
1345 vm_paging_target() + deficit + addl_page_shortage;
1347 pq = &vmd->vmd_pagequeues[PQ_ACTIVE];
1348 vm_pagequeue_lock(pq);
1349 maxscan = pq->pq_cnt;
1352 * If we're just idle polling attempt to visit every
1353 * active page within 'update_period' seconds.
1356 if (vm_pageout_update_period != 0) {
1357 min_scan = pq->pq_cnt;
1358 min_scan *= scan_tick - vmd->vmd_last_active_scan;
1359 min_scan /= hz * vm_pageout_update_period;
1362 if (min_scan > 0 || (page_shortage > 0 && maxscan > 0))
1363 vmd->vmd_last_active_scan = scan_tick;
1366 * Scan the active queue for pages that can be deactivated. Update
1367 * the per-page activity counter and use it to identify deactivation
1370 for (m = TAILQ_FIRST(&pq->pq_pl), scanned = 0; m != NULL && (scanned <
1371 min_scan || (page_shortage > 0 && scanned < maxscan)); m = next,
1374 KASSERT(m->queue == PQ_ACTIVE,
1375 ("vm_pageout_scan: page %p isn't active", m));
1377 next = TAILQ_NEXT(m, plinks.q);
1378 if ((m->flags & PG_MARKER) != 0)
1380 KASSERT((m->flags & PG_FICTITIOUS) == 0,
1381 ("Fictitious page %p cannot be in active queue", m));
1382 KASSERT((m->oflags & VPO_UNMANAGED) == 0,
1383 ("Unmanaged page %p cannot be in active queue", m));
1384 if (!vm_pageout_page_lock(m, &next)) {
1390 * The count for pagedaemon pages is done after checking the
1391 * page for eligibility...
1393 PCPU_INC(cnt.v_pdpages);
1396 * Check to see "how much" the page has been used.
1398 if ((m->aflags & PGA_REFERENCED) != 0) {
1399 vm_page_aflag_clear(m, PGA_REFERENCED);
1405 * Unlocked object ref count check. Two races are possible.
1406 * 1) The ref was transitioning to zero and we saw non-zero,
1407 * the pmap bits will be checked unnecessarily.
1408 * 2) The ref was transitioning to one and we saw zero.
1409 * The page lock prevents a new reference to this page so
1410 * we need not check the reference bits.
1412 if (m->object->ref_count != 0)
1413 act_delta += pmap_ts_referenced(m);
1416 * Advance or decay the act_count based on recent usage.
1418 if (act_delta != 0) {
1419 m->act_count += ACT_ADVANCE + act_delta;
1420 if (m->act_count > ACT_MAX)
1421 m->act_count = ACT_MAX;
1423 m->act_count -= min(m->act_count, ACT_DECLINE);
1426 * Move this page to the tail of the active or inactive
1427 * queue depending on usage.
1429 if (m->act_count == 0) {
1430 /* Dequeue to avoid later lock recursion. */
1431 vm_page_dequeue_locked(m);
1432 vm_page_deactivate(m);
1435 vm_page_requeue_locked(m);
1438 vm_pagequeue_unlock(pq);
1439 #if !defined(NO_SWAPPING)
1441 * Idle process swapout -- run once per second.
1443 if (vm_swap_idle_enabled) {
1445 if (time_second != lsec) {
1446 vm_req_vmdaemon(VM_SWAP_IDLE);
1453 * If we are critically low on one of RAM or swap and low on
1454 * the other, kill the largest process. However, we avoid
1455 * doing this on the first pass in order to give ourselves a
1456 * chance to flush out dirty vnode-backed pages and to allow
1457 * active pages to be moved to the inactive queue and reclaimed.
1459 vm_pageout_mightbe_oom(vmd, pass);
1462 static int vm_pageout_oom_vote;
1465 * The pagedaemon threads randlomly select one to perform the
1466 * OOM. Trying to kill processes before all pagedaemons
1467 * failed to reach free target is premature.
1470 vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass)
1474 if (pass <= 1 || !((swap_pager_avail < 64 && vm_page_count_min()) ||
1475 (swap_pager_full && vm_paging_target() > 0))) {
1477 vmd->vmd_oom = FALSE;
1478 atomic_subtract_int(&vm_pageout_oom_vote, 1);
1486 vmd->vmd_oom = TRUE;
1487 old_vote = atomic_fetchadd_int(&vm_pageout_oom_vote, 1);
1488 if (old_vote != vm_ndomains - 1)
1492 * The current pagedaemon thread is the last in the quorum to
1493 * start OOM. Initiate the selection and signaling of the
1496 vm_pageout_oom(VM_OOM_MEM);
1499 * After one round of OOM terror, recall our vote. On the
1500 * next pass, current pagedaemon would vote again if the low
1501 * memory condition is still there, due to vmd_oom being
1504 vmd->vmd_oom = FALSE;
1505 atomic_subtract_int(&vm_pageout_oom_vote, 1);
1509 vm_pageout_oom(int shortage)
1511 struct proc *p, *bigproc;
1512 vm_offset_t size, bigsize;
1517 * We keep the process bigproc locked once we find it to keep anyone
1518 * from messing with it; however, there is a possibility of
1519 * deadlock if process B is bigproc and one of it's child processes
1520 * attempts to propagate a signal to B while we are waiting for A's
1521 * lock while walking this list. To avoid this, we don't block on
1522 * the process lock but just skip a process if it is already locked.
1526 sx_slock(&allproc_lock);
1527 FOREACH_PROC_IN_SYSTEM(p) {
1533 * If this is a system, protected or killed process, skip it.
1535 if (p->p_state != PRS_NORMAL || (p->p_flag & (P_INEXEC |
1536 P_PROTECTED | P_SYSTEM | P_WEXIT)) != 0 ||
1537 p->p_pid == 1 || P_KILLED(p) ||
1538 (p->p_pid < 48 && swap_pager_avail != 0)) {
1543 * If the process is in a non-running type state,
1544 * don't touch it. Check all the threads individually.
1547 FOREACH_THREAD_IN_PROC(p, td) {
1549 if (!TD_ON_RUNQ(td) &&
1550 !TD_IS_RUNNING(td) &&
1551 !TD_IS_SLEEPING(td) &&
1552 !TD_IS_SUSPENDED(td)) {
1564 * get the process size
1566 vm = vmspace_acquire_ref(p);
1572 if (!vm_map_trylock_read(&vm->vm_map)) {
1579 size = vmspace_swap_count(vm);
1580 vm_map_unlock_read(&vm->vm_map);
1581 if (shortage == VM_OOM_MEM)
1582 size += vmspace_resident_count(vm);
1585 * if the this process is bigger than the biggest one
1588 if (size > bigsize) {
1589 if (bigproc != NULL)
1597 sx_sunlock(&allproc_lock);
1598 if (bigproc != NULL) {
1599 if (vm_panic_on_oom != 0)
1600 panic("out of swap space");
1602 killproc(bigproc, "out of swap space");
1603 sched_nice(bigproc, PRIO_MIN);
1605 PROC_UNLOCK(bigproc);
1606 wakeup(&vm_cnt.v_free_count);
1611 vm_pageout_worker(void *arg)
1613 struct vm_domain *domain;
1616 domidx = (uintptr_t)arg;
1617 domain = &vm_dom[domidx];
1620 * XXXKIB It could be useful to bind pageout daemon threads to
1621 * the cores belonging to the domain, from which vm_page_array
1625 KASSERT(domain->vmd_segs != 0, ("domain without segments"));
1626 domain->vmd_last_active_scan = ticks;
1627 vm_pageout_init_marker(&domain->vmd_marker, PQ_INACTIVE);
1630 * The pageout daemon worker is never done, so loop forever.
1634 * If we have enough free memory, wakeup waiters. Do
1635 * not clear vm_pages_needed until we reach our target,
1636 * otherwise we may be woken up over and over again and
1637 * waste a lot of cpu.
1639 mtx_lock(&vm_page_queue_free_mtx);
1640 if (vm_pages_needed && !vm_page_count_min()) {
1641 if (!vm_paging_needed())
1642 vm_pages_needed = 0;
1643 wakeup(&vm_cnt.v_free_count);
1645 if (vm_pages_needed) {
1647 * Still not done, take a second pass without waiting
1648 * (unlimited dirty cleaning), otherwise sleep a bit
1651 if (domain->vmd_pass > 1)
1652 msleep(&vm_pages_needed,
1653 &vm_page_queue_free_mtx, PVM, "psleep",
1657 * Good enough, sleep until required to refresh
1660 domain->vmd_pass = 0;
1661 msleep(&vm_pages_needed, &vm_page_queue_free_mtx,
1665 if (vm_pages_needed) {
1666 vm_cnt.v_pdwakeups++;
1669 mtx_unlock(&vm_page_queue_free_mtx);
1670 vm_pageout_scan(domain, domain->vmd_pass);
1675 * vm_pageout_init initialises basic pageout daemon settings.
1678 vm_pageout_init(void)
1681 * Initialize some paging parameters.
1683 vm_cnt.v_interrupt_free_min = 2;
1684 if (vm_cnt.v_page_count < 2000)
1685 vm_pageout_page_count = 8;
1688 * v_free_reserved needs to include enough for the largest
1689 * swap pager structures plus enough for any pv_entry structs
1692 if (vm_cnt.v_page_count > 1024)
1693 vm_cnt.v_free_min = 4 + (vm_cnt.v_page_count - 1024) / 200;
1695 vm_cnt.v_free_min = 4;
1696 vm_cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE +
1697 vm_cnt.v_interrupt_free_min;
1698 vm_cnt.v_free_reserved = vm_pageout_page_count +
1699 vm_cnt.v_pageout_free_min + (vm_cnt.v_page_count / 768);
1700 vm_cnt.v_free_severe = vm_cnt.v_free_min / 2;
1701 vm_cnt.v_free_target = 4 * vm_cnt.v_free_min + vm_cnt.v_free_reserved;
1702 vm_cnt.v_free_min += vm_cnt.v_free_reserved;
1703 vm_cnt.v_free_severe += vm_cnt.v_free_reserved;
1704 vm_cnt.v_inactive_target = (3 * vm_cnt.v_free_target) / 2;
1705 if (vm_cnt.v_inactive_target > vm_cnt.v_free_count / 3)
1706 vm_cnt.v_inactive_target = vm_cnt.v_free_count / 3;
1709 * Set the default wakeup threshold to be 10% above the minimum
1710 * page limit. This keeps the steady state out of shortfall.
1712 vm_pageout_wakeup_thresh = (vm_cnt.v_free_min / 10) * 11;
1715 * Set interval in seconds for active scan. We want to visit each
1716 * page at least once every ten minutes. This is to prevent worst
1717 * case paging behaviors with stale active LRU.
1719 if (vm_pageout_update_period == 0)
1720 vm_pageout_update_period = 600;
1722 /* XXX does not really belong here */
1723 if (vm_page_max_wired == 0)
1724 vm_page_max_wired = vm_cnt.v_free_count / 3;
1728 * vm_pageout is the high level pageout daemon.
1738 swap_pager_swap_init();
1740 for (i = 1; i < vm_ndomains; i++) {
1741 error = kthread_add(vm_pageout_worker, (void *)(uintptr_t)i,
1742 curproc, NULL, 0, 0, "dom%d", i);
1744 panic("starting pageout for domain %d, error %d\n",
1749 error = kthread_add(uma_reclaim_worker, NULL, curproc, NULL,
1752 panic("starting uma_reclaim helper, error %d\n", error);
1753 vm_pageout_worker((void *)(uintptr_t)0);
1757 * Unless the free page queue lock is held by the caller, this function
1758 * should be regarded as advisory. Specifically, the caller should
1759 * not msleep() on &vm_cnt.v_free_count following this function unless
1760 * the free page queue lock is held until the msleep() is performed.
1763 pagedaemon_wakeup(void)
1766 if (!vm_pages_needed && curthread->td_proc != pageproc) {
1767 vm_pages_needed = 1;
1768 wakeup(&vm_pages_needed);
1772 #if !defined(NO_SWAPPING)
1774 vm_req_vmdaemon(int req)
1776 static int lastrun = 0;
1778 mtx_lock(&vm_daemon_mtx);
1779 vm_pageout_req_swapout |= req;
1780 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
1781 wakeup(&vm_daemon_needed);
1784 mtx_unlock(&vm_daemon_mtx);
1790 struct rlimit rsslim;
1794 int breakout, swapout_flags, tryagain, attempts;
1796 uint64_t rsize, ravailable;
1800 mtx_lock(&vm_daemon_mtx);
1801 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep",
1803 racct_enable ? hz : 0
1808 swapout_flags = vm_pageout_req_swapout;
1809 vm_pageout_req_swapout = 0;
1810 mtx_unlock(&vm_daemon_mtx);
1812 swapout_procs(swapout_flags);
1815 * scan the processes for exceeding their rlimits or if
1816 * process is swapped out -- deactivate pages
1822 sx_slock(&allproc_lock);
1823 FOREACH_PROC_IN_SYSTEM(p) {
1824 vm_pindex_t limit, size;
1827 * if this is a system process or if we have already
1828 * looked at this process, skip it.
1831 if (p->p_state != PRS_NORMAL ||
1832 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) {
1837 * if the process is in a non-running type state,
1841 FOREACH_THREAD_IN_PROC(p, td) {
1843 if (!TD_ON_RUNQ(td) &&
1844 !TD_IS_RUNNING(td) &&
1845 !TD_IS_SLEEPING(td) &&
1846 !TD_IS_SUSPENDED(td)) {
1860 lim_rlimit_proc(p, RLIMIT_RSS, &rsslim);
1862 qmin(rsslim.rlim_cur, rsslim.rlim_max));
1865 * let processes that are swapped out really be
1866 * swapped out set the limit to nothing (will force a
1869 if ((p->p_flag & P_INMEM) == 0)
1870 limit = 0; /* XXX */
1871 vm = vmspace_acquire_ref(p);
1876 size = vmspace_resident_count(vm);
1877 if (size >= limit) {
1878 vm_pageout_map_deactivate_pages(
1879 &vm->vm_map, limit);
1883 rsize = IDX_TO_OFF(size);
1885 racct_set(p, RACCT_RSS, rsize);
1886 ravailable = racct_get_available(p, RACCT_RSS);
1888 if (rsize > ravailable) {
1890 * Don't be overly aggressive; this
1891 * might be an innocent process,
1892 * and the limit could've been exceeded
1893 * by some memory hog. Don't try
1894 * to deactivate more than 1/4th
1895 * of process' resident set size.
1897 if (attempts <= 8) {
1898 if (ravailable < rsize -
1900 ravailable = rsize -
1904 vm_pageout_map_deactivate_pages(
1906 OFF_TO_IDX(ravailable));
1907 /* Update RSS usage after paging out. */
1908 size = vmspace_resident_count(vm);
1909 rsize = IDX_TO_OFF(size);
1911 racct_set(p, RACCT_RSS, rsize);
1913 if (rsize > ravailable)
1920 sx_sunlock(&allproc_lock);
1921 if (tryagain != 0 && attempts <= 10)
1925 #endif /* !defined(NO_SWAPPING) */