2 * Copyright (c) 1991 Regents of the University of California.
4 * Copyright (c) 1994 John S. Dyson
6 * Copyright (c) 1994 David Greenman
9 * This code is derived from software contributed to Berkeley by
10 * The Mach Operating System project at Carnegie-Mellon University.
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
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. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
39 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
40 * All rights reserved.
42 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
44 * Permission to use, copy, modify and distribute this software and
45 * its documentation is hereby granted, provided that both the copyright
46 * notice and this permission notice appear in all copies of the
47 * software, derivative works or modified versions, and any portions
48 * thereof, and that both notices appear in supporting documentation.
50 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
51 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
52 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
54 * Carnegie Mellon requests users of this software to return to
56 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
57 * School of Computer Science
58 * Carnegie Mellon University
59 * Pittsburgh PA 15213-3890
61 * any improvements or extensions that they make and grant Carnegie the
62 * rights to redistribute these changes.
64 * $FreeBSD: src/sys/vm/vm_pageout.c,v 1.151.2.15 2002/12/29 18:21:04 dillon Exp $
68 * The proverbial page-out daemon.
72 #include <sys/param.h>
73 #include <sys/systm.h>
74 #include <sys/kernel.h>
76 #include <sys/kthread.h>
77 #include <sys/resourcevar.h>
78 #include <sys/signalvar.h>
79 #include <sys/vnode.h>
80 #include <sys/vmmeter.h>
82 #include <sys/sysctl.h>
85 #include <vm/vm_param.h>
87 #include <vm/vm_object.h>
88 #include <vm/vm_page.h>
89 #include <vm/vm_map.h>
90 #include <vm/vm_pageout.h>
91 #include <vm/vm_pager.h>
92 #include <vm/swap_pager.h>
93 #include <vm/vm_extern.h>
95 #include <sys/thread2.h>
96 #include <sys/spinlock2.h>
97 #include <vm/vm_page2.h>
100 * System initialization
103 /* the kernel process "vm_pageout"*/
104 static int vm_pageout_page(vm_page_t m
, int *max_launderp
,
105 int *vnodes_skippedp
, struct vnode
**vpfailedp
,
106 int pass
, int vmflush_flags
);
107 static int vm_pageout_clean_helper (vm_page_t
, int);
108 static int vm_pageout_free_page_calc (vm_size_t count
);
109 static void vm_pageout_page_free(vm_page_t m
) ;
110 struct thread
*emergpager
;
111 struct thread
*pagethread
;
112 static int sequence_emerg_pager
;
114 #if !defined(NO_SWAPPING)
115 /* the kernel process "vm_daemon"*/
116 static void vm_daemon (void);
117 static struct thread
*vmthread
;
119 static struct kproc_desc vm_kp
= {
124 SYSINIT(vmdaemon
, SI_SUB_KTHREAD_VM
, SI_ORDER_FIRST
, kproc_start
, &vm_kp
);
127 int vm_pages_needed
= 0; /* Event on which pageout daemon sleeps */
128 int vm_pageout_deficit
= 0; /* Estimated number of pages deficit */
129 int vm_pageout_pages_needed
= 0;/* pageout daemon needs pages */
130 int vm_page_free_hysteresis
= 16;
131 static int vm_pagedaemon_time
;
133 #if !defined(NO_SWAPPING)
134 static int vm_pageout_req_swapout
;
135 static int vm_daemon_needed
;
137 static int vm_max_launder
= 4096;
138 static int vm_emerg_launder
= 100;
139 static int vm_pageout_stats_max
=0, vm_pageout_stats_interval
= 0;
140 static int vm_pageout_full_stats_interval
= 0;
141 static int vm_pageout_stats_free_max
=0, vm_pageout_algorithm
=0;
142 static int defer_swap_pageouts
=0;
143 static int disable_swap_pageouts
=0;
144 static u_int vm_anonmem_decline
= ACT_DECLINE
;
145 static u_int vm_filemem_decline
= ACT_DECLINE
* 2;
147 #if defined(NO_SWAPPING)
148 static int vm_swap_enabled
=0;
149 static int vm_swap_idle_enabled
=0;
151 static int vm_swap_enabled
=1;
152 static int vm_swap_idle_enabled
=0;
154 int vm_pageout_memuse_mode
=1; /* 0-disable, 1-passive, 2-active swp*/
156 SYSCTL_UINT(_vm
, VM_PAGEOUT_ALGORITHM
, anonmem_decline
,
157 CTLFLAG_RW
, &vm_anonmem_decline
, 0, "active->inactive anon memory");
159 SYSCTL_INT(_vm
, VM_PAGEOUT_ALGORITHM
, filemem_decline
,
160 CTLFLAG_RW
, &vm_filemem_decline
, 0, "active->inactive file cache");
162 SYSCTL_INT(_vm
, OID_AUTO
, page_free_hysteresis
,
163 CTLFLAG_RW
, &vm_page_free_hysteresis
, 0,
164 "Free more pages than the minimum required");
166 SYSCTL_INT(_vm
, OID_AUTO
, max_launder
,
167 CTLFLAG_RW
, &vm_max_launder
, 0, "Limit dirty flushes in pageout");
168 SYSCTL_INT(_vm
, OID_AUTO
, emerg_launder
,
169 CTLFLAG_RW
, &vm_emerg_launder
, 0, "Emergency pager minimum");
171 SYSCTL_INT(_vm
, OID_AUTO
, pageout_stats_max
,
172 CTLFLAG_RW
, &vm_pageout_stats_max
, 0, "Max pageout stats scan length");
174 SYSCTL_INT(_vm
, OID_AUTO
, pageout_full_stats_interval
,
175 CTLFLAG_RW
, &vm_pageout_full_stats_interval
, 0, "Interval for full stats scan");
177 SYSCTL_INT(_vm
, OID_AUTO
, pageout_stats_interval
,
178 CTLFLAG_RW
, &vm_pageout_stats_interval
, 0, "Interval for partial stats scan");
180 SYSCTL_INT(_vm
, OID_AUTO
, pageout_stats_free_max
,
181 CTLFLAG_RW
, &vm_pageout_stats_free_max
, 0, "Not implemented");
182 SYSCTL_INT(_vm
, OID_AUTO
, pageout_memuse_mode
,
183 CTLFLAG_RW
, &vm_pageout_memuse_mode
, 0, "memoryuse resource mode");
185 #if defined(NO_SWAPPING)
186 SYSCTL_INT(_vm
, VM_SWAPPING_ENABLED
, swap_enabled
,
187 CTLFLAG_RD
, &vm_swap_enabled
, 0, "");
188 SYSCTL_INT(_vm
, OID_AUTO
, swap_idle_enabled
,
189 CTLFLAG_RD
, &vm_swap_idle_enabled
, 0, "");
191 SYSCTL_INT(_vm
, VM_SWAPPING_ENABLED
, swap_enabled
,
192 CTLFLAG_RW
, &vm_swap_enabled
, 0, "Enable entire process swapout");
193 SYSCTL_INT(_vm
, OID_AUTO
, swap_idle_enabled
,
194 CTLFLAG_RW
, &vm_swap_idle_enabled
, 0, "Allow swapout on idle criteria");
197 SYSCTL_INT(_vm
, OID_AUTO
, defer_swapspace_pageouts
,
198 CTLFLAG_RW
, &defer_swap_pageouts
, 0, "Give preference to dirty pages in mem");
200 SYSCTL_INT(_vm
, OID_AUTO
, disable_swapspace_pageouts
,
201 CTLFLAG_RW
, &disable_swap_pageouts
, 0, "Disallow swapout of dirty pages");
203 static int pageout_lock_miss
;
204 SYSCTL_INT(_vm
, OID_AUTO
, pageout_lock_miss
,
205 CTLFLAG_RD
, &pageout_lock_miss
, 0, "vget() lock misses during pageout");
207 int vm_page_max_wired
; /* XXX max # of wired pages system-wide */
209 #if !defined(NO_SWAPPING)
210 static void vm_req_vmdaemon (void);
212 static void vm_pageout_page_stats(int q
);
215 * Calculate approximately how many pages on each queue to try to
216 * clean. An exact calculation creates an edge condition when the
217 * queues are unbalanced so add significant slop. The queue scans
218 * will stop early when targets are reached and will start where they
219 * left off on the next pass.
221 * We need to be generous here because there are all sorts of loading
222 * conditions that can cause edge cases if try to average over all queues.
223 * In particular, storage subsystems have become so fast that paging
224 * activity can become quite frantic. Eventually we will probably need
225 * two paging threads, one for dirty pages and one for clean, to deal
226 * with the bandwidth requirements.
228 * So what we do is calculate a value that can be satisfied nominally by
229 * only having to scan half the queues.
237 avg
= ((n
+ (PQ_L2_SIZE
- 1)) / (PQ_L2_SIZE
/ 2) + 1);
239 avg
= ((n
- (PQ_L2_SIZE
- 1)) / (PQ_L2_SIZE
/ 2) - 1);
245 * vm_pageout_clean_helper:
247 * Clean the page and remove it from the laundry. The page must be busied
248 * by the caller and will be disposed of (put away, flushed) by this routine.
251 vm_pageout_clean_helper(vm_page_t m
, int vmflush_flags
)
254 vm_page_t mc
[BLIST_MAX_ALLOC
];
256 int ib
, is
, page_base
;
257 vm_pindex_t pindex
= m
->pindex
;
262 * Don't mess with the page if it's held or special.
264 * XXX do we really need to check hold_count here? hold_count
265 * isn't supposed to mess with vm_page ops except prevent the
266 * page from being reused.
268 if (m
->hold_count
!= 0 || (m
->flags
& PG_UNMANAGED
)) {
274 * Place page in cluster. Align cluster for optimal swap space
275 * allocation (whether it is swap or not). This is typically ~16-32
276 * pages, which also tends to align the cluster to multiples of the
277 * filesystem block size if backed by a filesystem.
279 page_base
= pindex
% BLIST_MAX_ALLOC
;
285 * Scan object for clusterable pages.
287 * We can cluster ONLY if: ->> the page is NOT
288 * clean, wired, busy, held, or mapped into a
289 * buffer, and one of the following:
290 * 1) The page is inactive, or a seldom used
293 * 2) we force the issue.
295 * During heavy mmap/modification loads the pageout
296 * daemon can really fragment the underlying file
297 * due to flushing pages out of order and not trying
298 * align the clusters (which leave sporatic out-of-order
299 * holes). To solve this problem we do the reverse scan
300 * first and attempt to align our cluster, then do a
301 * forward scan if room remains.
303 vm_object_hold(object
);
308 p
= vm_page_lookup_busy_try(object
, pindex
- page_base
+ ib
,
310 if (error
|| p
== NULL
)
312 if ((p
->queue
- p
->pc
) == PQ_CACHE
||
313 (p
->flags
& PG_UNMANAGED
)) {
317 vm_page_test_dirty(p
);
318 if (((p
->dirty
& p
->valid
) == 0 &&
319 (p
->flags
& PG_NEED_COMMIT
) == 0) ||
320 p
->wire_count
!= 0 || /* may be held by buf cache */
321 p
->hold_count
!= 0) { /* may be undergoing I/O */
325 if (p
->queue
- p
->pc
!= PQ_INACTIVE
) {
326 if (p
->queue
- p
->pc
!= PQ_ACTIVE
||
327 (vmflush_flags
& VM_PAGER_ALLOW_ACTIVE
) == 0) {
334 * Try to maintain page groupings in the cluster.
336 if (m
->flags
& PG_WINATCFLS
)
337 vm_page_flag_set(p
, PG_WINATCFLS
);
339 vm_page_flag_clear(p
, PG_WINATCFLS
);
340 p
->act_count
= m
->act_count
;
347 while (is
< BLIST_MAX_ALLOC
&&
348 pindex
- page_base
+ is
< object
->size
) {
351 p
= vm_page_lookup_busy_try(object
, pindex
- page_base
+ is
,
353 if (error
|| p
== NULL
)
355 if (((p
->queue
- p
->pc
) == PQ_CACHE
) ||
356 (p
->flags
& PG_UNMANAGED
)) {
360 vm_page_test_dirty(p
);
361 if (((p
->dirty
& p
->valid
) == 0 &&
362 (p
->flags
& PG_NEED_COMMIT
) == 0) ||
363 p
->wire_count
!= 0 || /* may be held by buf cache */
364 p
->hold_count
!= 0) { /* may be undergoing I/O */
368 if (p
->queue
- p
->pc
!= PQ_INACTIVE
) {
369 if (p
->queue
- p
->pc
!= PQ_ACTIVE
||
370 (vmflush_flags
& VM_PAGER_ALLOW_ACTIVE
) == 0) {
377 * Try to maintain page groupings in the cluster.
379 if (m
->flags
& PG_WINATCFLS
)
380 vm_page_flag_set(p
, PG_WINATCFLS
);
382 vm_page_flag_clear(p
, PG_WINATCFLS
);
383 p
->act_count
= m
->act_count
;
389 vm_object_drop(object
);
392 * we allow reads during pageouts...
394 return vm_pageout_flush(&mc
[ib
], is
- ib
, vmflush_flags
);
398 * vm_pageout_flush() - launder the given pages
400 * The given pages are laundered. Note that we setup for the start of
401 * I/O ( i.e. busy the page ), mark it read-only, and bump the object
402 * reference count all in here rather then in the parent. If we want
403 * the parent to do more sophisticated things we may have to change
406 * The pages in the array must be busied by the caller and will be
407 * unbusied by this function.
410 vm_pageout_flush(vm_page_t
*mc
, int count
, int vmflush_flags
)
413 int pageout_status
[count
];
418 * Initiate I/O. Bump the vm_page_t->busy counter.
420 for (i
= 0; i
< count
; i
++) {
421 KASSERT(mc
[i
]->valid
== VM_PAGE_BITS_ALL
,
422 ("vm_pageout_flush page %p index %d/%d: partially "
423 "invalid page", mc
[i
], i
, count
));
424 vm_page_io_start(mc
[i
]);
428 * We must make the pages read-only. This will also force the
429 * modified bit in the related pmaps to be cleared. The pager
430 * cannot clear the bit for us since the I/O completion code
431 * typically runs from an interrupt. The act of making the page
432 * read-only handles the case for us.
434 * Then we can unbusy the pages, we still hold a reference by virtue
437 for (i
= 0; i
< count
; i
++) {
438 if (vmflush_flags
& VM_PAGER_TRY_TO_CACHE
)
439 vm_page_protect(mc
[i
], VM_PROT_NONE
);
441 vm_page_protect(mc
[i
], VM_PROT_READ
);
442 vm_page_wakeup(mc
[i
]);
445 object
= mc
[0]->object
;
446 vm_object_pip_add(object
, count
);
448 vm_pager_put_pages(object
, mc
, count
,
450 ((object
== &kernel_object
) ?
451 VM_PAGER_PUT_SYNC
: 0)),
454 for (i
= 0; i
< count
; i
++) {
455 vm_page_t mt
= mc
[i
];
457 switch (pageout_status
[i
]) {
466 * Page outside of range of object. Right now we
467 * essentially lose the changes by pretending it
470 vm_page_busy_wait(mt
, FALSE
, "pgbad");
471 pmap_clear_modify(mt
);
478 * A page typically cannot be paged out when we
479 * have run out of swap. We leave the page
480 * marked inactive and will try to page it out
483 * Starvation of the active page list is used to
484 * determine when the system is massively memory
493 * If not PENDing this was a synchronous operation and we
494 * clean up after the I/O. If it is PENDing the mess is
495 * cleaned up asynchronously.
497 * Also nominally act on the caller's wishes if the caller
498 * wants to try to really clean (cache or free) the page.
500 * Also nominally deactivate the page if the system is
503 if (pageout_status
[i
] != VM_PAGER_PEND
) {
504 vm_page_busy_wait(mt
, FALSE
, "pgouw");
505 vm_page_io_finish(mt
);
506 if (vmflush_flags
& VM_PAGER_TRY_TO_CACHE
) {
507 vm_page_try_to_cache(mt
);
508 } else if (vm_page_count_severe()) {
509 vm_page_deactivate(mt
);
514 vm_object_pip_wakeup(object
);
520 #if !defined(NO_SWAPPING)
523 * Callback function, page busied for us. We must dispose of the busy
524 * condition. Any related pmap pages may be held but will not be locked.
528 vm_pageout_mdp_callback(struct pmap_pgscan_info
*info
, vm_offset_t va
,
535 * Basic tests - There should never be a marker, and we can stop
536 * once the RSS is below the required level.
538 KKASSERT((p
->flags
& PG_MARKER
) == 0);
539 if (pmap_resident_tlnw_count(info
->pmap
) <= info
->limit
) {
544 mycpu
->gd_cnt
.v_pdpages
++;
546 if (p
->wire_count
|| p
->hold_count
|| (p
->flags
& PG_UNMANAGED
)) {
554 * Check if the page has been referened recently. If it has,
555 * activate it and skip.
557 actcount
= pmap_ts_referenced(p
);
559 vm_page_flag_set(p
, PG_REFERENCED
);
560 } else if (p
->flags
& PG_REFERENCED
) {
565 if (p
->queue
- p
->pc
!= PQ_ACTIVE
) {
566 vm_page_and_queue_spin_lock(p
);
567 if (p
->queue
- p
->pc
!= PQ_ACTIVE
) {
568 vm_page_and_queue_spin_unlock(p
);
571 vm_page_and_queue_spin_unlock(p
);
574 p
->act_count
+= actcount
;
575 if (p
->act_count
> ACT_MAX
)
576 p
->act_count
= ACT_MAX
;
578 vm_page_flag_clear(p
, PG_REFERENCED
);
584 * Remove the page from this particular pmap. Once we do this, our
585 * pmap scans will not see it again (unless it gets faulted in), so
586 * we must actively dispose of or deal with the page.
588 pmap_remove_specific(info
->pmap
, p
);
591 * If the page is not mapped to another process (i.e. as would be
592 * typical if this were a shared page from a library) then deactivate
593 * the page and clean it in two passes only.
595 * If the page hasn't been referenced since the last check, remove it
596 * from the pmap. If it is no longer mapped, deactivate it
597 * immediately, accelerating the normal decline.
599 * Once the page has been removed from the pmap the RSS code no
600 * longer tracks it so we have to make sure that it is staged for
601 * potential flush action.
603 if ((p
->flags
& PG_MAPPED
) == 0) {
604 if (p
->queue
- p
->pc
== PQ_ACTIVE
) {
605 vm_page_deactivate(p
);
607 if (p
->queue
- p
->pc
== PQ_INACTIVE
) {
613 * Ok, try to fully clean the page and any nearby pages such that at
614 * least the requested page is freed or moved to the cache queue.
616 * We usually do this synchronously to allow us to get the page into
617 * the CACHE queue quickly, which will prevent memory exhaustion if
618 * a process with a memoryuse limit is running away. However, the
619 * sysadmin may desire to set vm.swap_user_async which relaxes this
620 * and improves write performance.
623 int max_launder
= 0x7FFF;
624 int vnodes_skipped
= 0;
626 struct vnode
*vpfailed
= NULL
;
630 if (vm_pageout_memuse_mode
>= 2) {
631 vmflush_flags
= VM_PAGER_TRY_TO_CACHE
|
632 VM_PAGER_ALLOW_ACTIVE
;
633 if (swap_user_async
== 0)
634 vmflush_flags
|= VM_PAGER_PUT_SYNC
;
635 vm_page_flag_set(p
, PG_WINATCFLS
);
637 vm_pageout_page(p
, &max_launder
,
639 &vpfailed
, 1, vmflush_flags
);
649 * Must be at end to avoid SMP races.
657 * Deactivate some number of pages in a map due to set RLIMIT_RSS limits.
658 * that is relatively difficult to do. We try to keep track of where we
659 * left off last time to reduce scan overhead.
661 * Called when vm_pageout_memuse_mode is >= 1.
664 vm_pageout_map_deactivate_pages(vm_map_t map
, vm_pindex_t limit
)
666 vm_offset_t pgout_offset
;
667 struct pmap_pgscan_info info
;
670 pgout_offset
= map
->pgout_offset
;
673 kprintf("%016jx ", pgout_offset
);
675 if (pgout_offset
< VM_MIN_USER_ADDRESS
)
676 pgout_offset
= VM_MIN_USER_ADDRESS
;
677 if (pgout_offset
>= VM_MAX_USER_ADDRESS
)
679 info
.pmap
= vm_map_pmap(map
);
681 info
.beg_addr
= pgout_offset
;
682 info
.end_addr
= VM_MAX_USER_ADDRESS
;
683 info
.callback
= vm_pageout_mdp_callback
;
685 info
.actioncount
= 0;
689 pgout_offset
= info
.offset
;
691 kprintf("%016jx %08lx %08lx\n", pgout_offset
,
692 info
.cleancount
, info
.actioncount
);
695 if (pgout_offset
!= VM_MAX_USER_ADDRESS
&&
696 pmap_resident_tlnw_count(vm_map_pmap(map
)) > limit
) {
698 } else if (retries
&&
699 pmap_resident_tlnw_count(vm_map_pmap(map
)) > limit
) {
703 map
->pgout_offset
= pgout_offset
;
708 * Called when the pageout scan wants to free a page. We no longer
709 * try to cycle the vm_object here with a reference & dealloc, which can
710 * cause a non-trivial object collapse in a critical path.
712 * It is unclear why we cycled the ref_count in the past, perhaps to try
713 * to optimize shadow chain collapses but I don't quite see why it would
714 * be necessary. An OBJ_DEAD object should terminate any and all vm_pages
715 * synchronously and not have to be kicked-start.
718 vm_pageout_page_free(vm_page_t m
)
720 vm_page_protect(m
, VM_PROT_NONE
);
725 * vm_pageout_scan does the dirty work for the pageout daemon.
727 struct vm_pageout_scan_info
{
728 struct proc
*bigproc
;
732 static int vm_pageout_scan_callback(struct proc
*p
, void *data
);
735 * Scan inactive queue
737 * WARNING! Can be called from two pagedaemon threads simultaneously.
740 vm_pageout_scan_inactive(int pass
, int q
, int avail_shortage
,
744 struct vm_page marker
;
745 struct vnode
*vpfailed
; /* warning, allowed to be stale */
751 isep
= (curthread
== emergpager
);
754 * Start scanning the inactive queue for pages we can move to the
755 * cache or free. The scan will stop when the target is reached or
756 * we have scanned the entire inactive queue. Note that m->act_count
757 * is not used to form decisions for the inactive queue, only for the
760 * max_launder limits the number of dirty pages we flush per scan.
761 * For most systems a smaller value (16 or 32) is more robust under
762 * extreme memory and disk pressure because any unnecessary writes
763 * to disk can result in extreme performance degredation. However,
764 * systems with excessive dirty pages (especially when MAP_NOSYNC is
765 * used) will die horribly with limited laundering. If the pageout
766 * daemon cannot clean enough pages in the first pass, we let it go
767 * all out in succeeding passes.
769 * NOTE! THE EMERGENCY PAGER (isep) DOES NOT LAUNDER VNODE-BACKED
772 if ((max_launder
= vm_max_launder
) <= 1)
778 * Initialize our marker
780 bzero(&marker
, sizeof(marker
));
781 marker
.flags
= PG_BUSY
| PG_FICTITIOUS
| PG_MARKER
;
782 marker
.queue
= PQ_INACTIVE
+ q
;
784 marker
.wire_count
= 1;
787 * Inactive queue scan.
789 * NOTE: The vm_page must be spinlocked before the queue to avoid
790 * deadlocks, so it is easiest to simply iterate the loop
791 * with the queue unlocked at the top.
795 vm_page_queues_spin_lock(PQ_INACTIVE
+ q
);
796 TAILQ_INSERT_HEAD(&vm_page_queues
[PQ_INACTIVE
+ q
].pl
, &marker
, pageq
);
797 maxscan
= vm_page_queues
[PQ_INACTIVE
+ q
].lcnt
;
800 * Queue locked at top of loop to avoid stack marker issues.
802 while ((m
= TAILQ_NEXT(&marker
, pageq
)) != NULL
&&
803 maxscan
-- > 0 && avail_shortage
- delta
> 0)
807 KKASSERT(m
->queue
== PQ_INACTIVE
+ q
);
808 TAILQ_REMOVE(&vm_page_queues
[PQ_INACTIVE
+ q
].pl
,
810 TAILQ_INSERT_AFTER(&vm_page_queues
[PQ_INACTIVE
+ q
].pl
, m
,
812 mycpu
->gd_cnt
.v_pdpages
++;
815 * Skip marker pages (atomic against other markers to avoid
816 * infinite hop-over scans).
818 if (m
->flags
& PG_MARKER
)
822 * Try to busy the page. Don't mess with pages which are
823 * already busy or reorder them in the queue.
825 if (vm_page_busy_try(m
, TRUE
))
829 * Remaining operations run with the page busy and neither
830 * the page or the queue will be spin-locked.
832 vm_page_queues_spin_unlock(PQ_INACTIVE
+ q
);
833 KKASSERT(m
->queue
== PQ_INACTIVE
+ q
);
836 * The emergency pager runs when the primary pager gets
837 * stuck, which typically means the primary pager deadlocked
838 * on a vnode-backed page. Therefore, the emergency pager
839 * must skip any complex objects.
841 * We disallow VNODEs unless they are VCHR whos device ops
842 * does not flag D_NOEMERGPGR.
844 if (isep
&& m
->object
) {
847 switch(m
->object
->type
) {
851 * Allow anonymous memory and assume that
852 * swap devices are not complex, since its
853 * kinda worthless if we can't swap out dirty
859 * Allow VCHR device if the D_NOEMERGPGR
860 * flag is not set, deny other vnode types
861 * as being too complex.
863 vp
= m
->object
->handle
;
864 if (vp
&& vp
->v_type
== VCHR
&&
865 vp
->v_rdev
&& vp
->v_rdev
->si_ops
&&
866 (vp
->v_rdev
->si_ops
->head
.flags
&
867 D_NOEMERGPGR
) == 0) {
870 /* Deny - fall through */
876 vm_page_queues_spin_lock(PQ_INACTIVE
+ q
);
883 * Try to pageout the page and perhaps other nearby pages.
885 count
= vm_pageout_page(m
, &max_launder
, vnodes_skipped
,
890 * Systems with a ton of memory can wind up with huge
891 * deactivation counts. Because the inactive scan is
892 * doing a lot of flushing, the combination can result
893 * in excessive paging even in situations where other
894 * unrelated threads free up sufficient VM.
896 * To deal with this we abort the nominal active->inactive
897 * scan before we hit the inactive target when free+cache
898 * levels have reached a reasonable target.
900 * When deciding to stop early we need to add some slop to
901 * the test and we need to return full completion to the caller
902 * to prevent the caller from thinking there is something
903 * wrong and issuing a low-memory+swap warning or pkill.
905 * A deficit forces paging regardless of the state of the
906 * VM page queues (used for RSS enforcement).
909 vm_page_queues_spin_lock(PQ_INACTIVE
+ q
);
910 if (vm_paging_target() < -vm_max_launder
) {
912 * Stopping early, return full completion to caller.
914 if (delta
< avail_shortage
)
915 delta
= avail_shortage
;
920 /* page queue still spin-locked */
921 TAILQ_REMOVE(&vm_page_queues
[PQ_INACTIVE
+ q
].pl
, &marker
, pageq
);
922 vm_page_queues_spin_unlock(PQ_INACTIVE
+ q
);
928 * Pageout the specified page, return the total number of pages paged out
929 * (this routine may cluster).
931 * The page must be busied and soft-busied by the caller and will be disposed
932 * of by this function.
935 vm_pageout_page(vm_page_t m
, int *max_launderp
, int *vnodes_skippedp
,
936 struct vnode
**vpfailedp
, int pass
, int vmflush_flags
)
943 * It is possible for a page to be busied ad-hoc (e.g. the
944 * pmap_collect() code) and wired and race against the
945 * allocation of a new page. vm_page_alloc() may be forced
946 * to deactivate the wired page in which case it winds up
947 * on the inactive queue and must be handled here. We
948 * correct the problem simply by unqueuing the page.
951 vm_page_unqueue_nowakeup(m
);
953 kprintf("WARNING: pagedaemon: wired page on "
954 "inactive queue %p\n", m
);
959 * A held page may be undergoing I/O, so skip it.
962 vm_page_and_queue_spin_lock(m
);
963 if (m
->queue
- m
->pc
== PQ_INACTIVE
) {
965 &vm_page_queues
[m
->queue
].pl
, m
, pageq
);
967 &vm_page_queues
[m
->queue
].pl
, m
, pageq
);
968 ++vm_swapcache_inactive_heuristic
;
970 vm_page_and_queue_spin_unlock(m
);
975 if (m
->object
== NULL
|| m
->object
->ref_count
== 0) {
977 * If the object is not being used, we ignore previous
980 vm_page_flag_clear(m
, PG_REFERENCED
);
981 pmap_clear_reference(m
);
982 /* fall through to end */
983 } else if (((m
->flags
& PG_REFERENCED
) == 0) &&
984 (actcount
= pmap_ts_referenced(m
))) {
986 * Otherwise, if the page has been referenced while
987 * in the inactive queue, we bump the "activation
988 * count" upwards, making it less likely that the
989 * page will be added back to the inactive queue
990 * prematurely again. Here we check the page tables
991 * (or emulated bits, if any), given the upper level
992 * VM system not knowing anything about existing
996 m
->act_count
+= (actcount
+ ACT_ADVANCE
);
1002 * (m) is still busied.
1004 * If the upper level VM system knows about any page
1005 * references, we activate the page. We also set the
1006 * "activation count" higher than normal so that we will less
1007 * likely place pages back onto the inactive queue again.
1009 if ((m
->flags
& PG_REFERENCED
) != 0) {
1010 vm_page_flag_clear(m
, PG_REFERENCED
);
1011 actcount
= pmap_ts_referenced(m
);
1012 vm_page_activate(m
);
1013 m
->act_count
+= (actcount
+ ACT_ADVANCE
+ 1);
1019 * If the upper level VM system doesn't know anything about
1020 * the page being dirty, we have to check for it again. As
1021 * far as the VM code knows, any partially dirty pages are
1024 * Pages marked PG_WRITEABLE may be mapped into the user
1025 * address space of a process running on another cpu. A
1026 * user process (without holding the MP lock) running on
1027 * another cpu may be able to touch the page while we are
1028 * trying to remove it. vm_page_cache() will handle this
1031 if (m
->dirty
== 0) {
1032 vm_page_test_dirty(m
);
1037 if (m
->valid
== 0 && (m
->flags
& PG_NEED_COMMIT
) == 0) {
1039 * Invalid pages can be easily freed
1041 vm_pageout_page_free(m
);
1042 mycpu
->gd_cnt
.v_dfree
++;
1044 } else if (m
->dirty
== 0 && (m
->flags
& PG_NEED_COMMIT
) == 0) {
1046 * Clean pages can be placed onto the cache queue.
1047 * This effectively frees them.
1051 } else if ((m
->flags
& PG_WINATCFLS
) == 0 && pass
== 0) {
1053 * Dirty pages need to be paged out, but flushing
1054 * a page is extremely expensive verses freeing
1055 * a clean page. Rather then artificially limiting
1056 * the number of pages we can flush, we instead give
1057 * dirty pages extra priority on the inactive queue
1058 * by forcing them to be cycled through the queue
1059 * twice before being flushed, after which the
1060 * (now clean) page will cycle through once more
1061 * before being freed. This significantly extends
1062 * the thrash point for a heavily loaded machine.
1064 vm_page_flag_set(m
, PG_WINATCFLS
);
1065 vm_page_and_queue_spin_lock(m
);
1066 if (m
->queue
- m
->pc
== PQ_INACTIVE
) {
1068 &vm_page_queues
[m
->queue
].pl
, m
, pageq
);
1070 &vm_page_queues
[m
->queue
].pl
, m
, pageq
);
1071 ++vm_swapcache_inactive_heuristic
;
1073 vm_page_and_queue_spin_unlock(m
);
1075 } else if (*max_launderp
> 0) {
1077 * We always want to try to flush some dirty pages if
1078 * we encounter them, to keep the system stable.
1079 * Normally this number is small, but under extreme
1080 * pressure where there are insufficient clean pages
1081 * on the inactive queue, we may have to go all out.
1083 int swap_pageouts_ok
;
1084 struct vnode
*vp
= NULL
;
1086 swap_pageouts_ok
= 0;
1089 (object
->type
!= OBJT_SWAP
) &&
1090 (object
->type
!= OBJT_DEFAULT
)) {
1091 swap_pageouts_ok
= 1;
1093 swap_pageouts_ok
= !(defer_swap_pageouts
||
1094 disable_swap_pageouts
);
1095 swap_pageouts_ok
|= (!disable_swap_pageouts
&&
1096 defer_swap_pageouts
&&
1097 vm_page_count_min(0));
1101 * We don't bother paging objects that are "dead".
1102 * Those objects are in a "rundown" state.
1104 if (!swap_pageouts_ok
||
1106 (object
->flags
& OBJ_DEAD
)) {
1107 vm_page_and_queue_spin_lock(m
);
1108 if (m
->queue
- m
->pc
== PQ_INACTIVE
) {
1110 &vm_page_queues
[m
->queue
].pl
,
1113 &vm_page_queues
[m
->queue
].pl
,
1115 ++vm_swapcache_inactive_heuristic
;
1117 vm_page_and_queue_spin_unlock(m
);
1123 * (m) is still busied.
1125 * The object is already known NOT to be dead. It
1126 * is possible for the vget() to block the whole
1127 * pageout daemon, but the new low-memory handling
1128 * code should prevent it.
1130 * The previous code skipped locked vnodes and, worse,
1131 * reordered pages in the queue. This results in
1132 * completely non-deterministic operation because,
1133 * quite often, a vm_fault has initiated an I/O and
1134 * is holding a locked vnode at just the point where
1135 * the pageout daemon is woken up.
1137 * We can't wait forever for the vnode lock, we might
1138 * deadlock due to a vn_read() getting stuck in
1139 * vm_wait while holding this vnode. We skip the
1140 * vnode if we can't get it in a reasonable amount
1143 * vpfailed is used to (try to) avoid the case where
1144 * a large number of pages are associated with a
1145 * locked vnode, which could cause the pageout daemon
1146 * to stall for an excessive amount of time.
1148 if (object
->type
== OBJT_VNODE
) {
1151 vp
= object
->handle
;
1152 flags
= LK_EXCLUSIVE
;
1153 if (vp
== *vpfailedp
)
1156 flags
|= LK_TIMELOCK
;
1161 * We have unbusied (m) temporarily so we can
1162 * acquire the vp lock without deadlocking.
1163 * (m) is held to prevent destruction.
1165 if (vget(vp
, flags
) != 0) {
1167 ++pageout_lock_miss
;
1168 if (object
->flags
& OBJ_MIGHTBEDIRTY
)
1175 * The page might have been moved to another
1176 * queue during potential blocking in vget()
1177 * above. The page might have been freed and
1178 * reused for another vnode. The object might
1179 * have been reused for another vnode.
1181 if (m
->queue
- m
->pc
!= PQ_INACTIVE
||
1182 m
->object
!= object
||
1183 object
->handle
!= vp
) {
1184 if (object
->flags
& OBJ_MIGHTBEDIRTY
)
1192 * The page may have been busied during the
1193 * blocking in vput(); We don't move the
1194 * page back onto the end of the queue so that
1195 * statistics are more correct if we don't.
1197 if (vm_page_busy_try(m
, TRUE
)) {
1205 * (m) is busied again
1207 * We own the busy bit and remove our hold
1208 * bit. If the page is still held it
1209 * might be undergoing I/O, so skip it.
1211 if (m
->hold_count
) {
1212 vm_page_and_queue_spin_lock(m
);
1213 if (m
->queue
- m
->pc
== PQ_INACTIVE
) {
1214 TAILQ_REMOVE(&vm_page_queues
[m
->queue
].pl
, m
, pageq
);
1215 TAILQ_INSERT_TAIL(&vm_page_queues
[m
->queue
].pl
, m
, pageq
);
1216 ++vm_swapcache_inactive_heuristic
;
1218 vm_page_and_queue_spin_unlock(m
);
1219 if (object
->flags
& OBJ_MIGHTBEDIRTY
)
1225 /* (m) is left busied as we fall through */
1229 * page is busy and not held here.
1231 * If a page is dirty, then it is either being washed
1232 * (but not yet cleaned) or it is still in the
1233 * laundry. If it is still in the laundry, then we
1234 * start the cleaning operation.
1236 * decrement inactive_shortage on success to account
1237 * for the (future) cleaned page. Otherwise we
1238 * could wind up laundering or cleaning too many
1241 * NOTE: Cleaning the page here does not cause
1242 * force_deficit to be adjusted, because the
1243 * page is not being freed or moved to the
1246 count
= vm_pageout_clean_helper(m
, vmflush_flags
);
1247 *max_launderp
-= count
;
1250 * Clean ate busy, page no longer accessible
1263 * WARNING! Can be called from two pagedaemon threads simultaneously.
1266 vm_pageout_scan_active(int pass
, int q
,
1267 int avail_shortage
, int inactive_shortage
,
1268 int *recycle_countp
)
1270 struct vm_page marker
;
1277 isep
= (curthread
== emergpager
);
1280 * We want to move pages from the active queue to the inactive
1281 * queue to get the inactive queue to the inactive target. If
1282 * we still have a page shortage from above we try to directly free
1283 * clean pages instead of moving them.
1285 * If we do still have a shortage we keep track of the number of
1286 * pages we free or cache (recycle_count) as a measure of thrashing
1287 * between the active and inactive queues.
1289 * If we were able to completely satisfy the free+cache targets
1290 * from the inactive pool we limit the number of pages we move
1291 * from the active pool to the inactive pool to 2x the pages we
1292 * had removed from the inactive pool (with a minimum of 1/5 the
1293 * inactive target). If we were not able to completely satisfy
1294 * the free+cache targets we go for the whole target aggressively.
1296 * NOTE: Both variables can end up negative.
1297 * NOTE: We are still in a critical section.
1299 * NOTE! THE EMERGENCY PAGER (isep) DOES NOT LAUNDER VNODE-BACKED
1303 bzero(&marker
, sizeof(marker
));
1304 marker
.flags
= PG_BUSY
| PG_FICTITIOUS
| PG_MARKER
;
1305 marker
.queue
= PQ_ACTIVE
+ q
;
1307 marker
.wire_count
= 1;
1309 vm_page_queues_spin_lock(PQ_ACTIVE
+ q
);
1310 TAILQ_INSERT_HEAD(&vm_page_queues
[PQ_ACTIVE
+ q
].pl
, &marker
, pageq
);
1311 maxscan
= vm_page_queues
[PQ_ACTIVE
+ q
].lcnt
;
1314 * Queue locked at top of loop to avoid stack marker issues.
1316 while ((m
= TAILQ_NEXT(&marker
, pageq
)) != NULL
&&
1317 maxscan
-- > 0 && (avail_shortage
- delta
> 0 ||
1318 inactive_shortage
> 0))
1320 KKASSERT(m
->queue
== PQ_ACTIVE
+ q
);
1321 TAILQ_REMOVE(&vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1323 TAILQ_INSERT_AFTER(&vm_page_queues
[PQ_ACTIVE
+ q
].pl
, m
,
1327 * Skip marker pages (atomic against other markers to avoid
1328 * infinite hop-over scans).
1330 if (m
->flags
& PG_MARKER
)
1334 * Try to busy the page. Don't mess with pages which are
1335 * already busy or reorder them in the queue.
1337 if (vm_page_busy_try(m
, TRUE
))
1341 * Remaining operations run with the page busy and neither
1342 * the page or the queue will be spin-locked.
1344 vm_page_queues_spin_unlock(PQ_ACTIVE
+ q
);
1345 KKASSERT(m
->queue
== PQ_ACTIVE
+ q
);
1348 * Don't deactivate pages that are held, even if we can
1349 * busy them. (XXX why not?)
1351 if (m
->hold_count
!= 0) {
1352 vm_page_and_queue_spin_lock(m
);
1353 if (m
->queue
- m
->pc
== PQ_ACTIVE
) {
1355 &vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1358 &vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1361 vm_page_and_queue_spin_unlock(m
);
1367 * The emergency pager ignores vnode-backed pages as these
1368 * are the pages that probably bricked the main pager.
1370 if (isep
&& m
->object
&& m
->object
->type
== OBJT_VNODE
) {
1371 vm_page_and_queue_spin_lock(m
);
1372 if (m
->queue
- m
->pc
== PQ_ACTIVE
) {
1374 &vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1377 &vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1380 vm_page_and_queue_spin_unlock(m
);
1386 * The count for pagedaemon pages is done after checking the
1387 * page for eligibility...
1389 mycpu
->gd_cnt
.v_pdpages
++;
1392 * Check to see "how much" the page has been used and clear
1393 * the tracking access bits. If the object has no references
1394 * don't bother paying the expense.
1397 if (m
->object
&& m
->object
->ref_count
!= 0) {
1398 if (m
->flags
& PG_REFERENCED
)
1400 actcount
+= pmap_ts_referenced(m
);
1402 m
->act_count
+= ACT_ADVANCE
+ actcount
;
1403 if (m
->act_count
> ACT_MAX
)
1404 m
->act_count
= ACT_MAX
;
1407 vm_page_flag_clear(m
, PG_REFERENCED
);
1410 * actcount is only valid if the object ref_count is non-zero.
1411 * If the page does not have an object, actcount will be zero.
1413 if (actcount
&& m
->object
->ref_count
!= 0) {
1414 vm_page_and_queue_spin_lock(m
);
1415 if (m
->queue
- m
->pc
== PQ_ACTIVE
) {
1417 &vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1420 &vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1423 vm_page_and_queue_spin_unlock(m
);
1426 switch(m
->object
->type
) {
1429 m
->act_count
-= min(m
->act_count
,
1430 vm_anonmem_decline
);
1433 m
->act_count
-= min(m
->act_count
,
1434 vm_filemem_decline
);
1437 if (vm_pageout_algorithm
||
1438 (m
->object
== NULL
) ||
1439 (m
->object
&& (m
->object
->ref_count
== 0)) ||
1440 m
->act_count
< pass
+ 1
1443 * Deactivate the page. If we had a
1444 * shortage from our inactive scan try to
1445 * free (cache) the page instead.
1447 * Don't just blindly cache the page if
1448 * we do not have a shortage from the
1449 * inactive scan, that could lead to
1450 * gigabytes being moved.
1452 --inactive_shortage
;
1453 if (avail_shortage
- delta
> 0 ||
1454 (m
->object
&& (m
->object
->ref_count
== 0)))
1456 if (avail_shortage
- delta
> 0)
1458 vm_page_protect(m
, VM_PROT_NONE
);
1459 if (m
->dirty
== 0 &&
1460 (m
->flags
& PG_NEED_COMMIT
) == 0 &&
1461 avail_shortage
- delta
> 0) {
1464 vm_page_deactivate(m
);
1468 vm_page_deactivate(m
);
1473 vm_page_and_queue_spin_lock(m
);
1474 if (m
->queue
- m
->pc
== PQ_ACTIVE
) {
1476 &vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1479 &vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1482 vm_page_and_queue_spin_unlock(m
);
1488 vm_page_queues_spin_lock(PQ_ACTIVE
+ q
);
1492 * Clean out our local marker.
1494 * Page queue still spin-locked.
1496 TAILQ_REMOVE(&vm_page_queues
[PQ_ACTIVE
+ q
].pl
, &marker
, pageq
);
1497 vm_page_queues_spin_unlock(PQ_ACTIVE
+ q
);
1503 * The number of actually free pages can drop down to v_free_reserved,
1504 * we try to build the free count back above v_free_min. Note that
1505 * vm_paging_needed() also returns TRUE if v_free_count is not at
1506 * least v_free_min so that is the minimum we must build the free
1509 * We use a slightly higher target to improve hysteresis,
1510 * ((v_free_target + v_free_min) / 2). Since v_free_target
1511 * is usually the same as v_cache_min this maintains about
1512 * half the pages in the free queue as are in the cache queue,
1513 * providing pretty good pipelining for pageout operation.
1515 * The system operator can manipulate vm.v_cache_min and
1516 * vm.v_free_target to tune the pageout demon. Be sure
1517 * to keep vm.v_free_min < vm.v_free_target.
1519 * Note that the original paging target is to get at least
1520 * (free_min + cache_min) into (free + cache). The slightly
1521 * higher target will shift additional pages from cache to free
1522 * without effecting the original paging target in order to
1523 * maintain better hysteresis and not have the free count always
1524 * be dead-on v_free_min.
1526 * NOTE: we are still in a critical section.
1528 * Pages moved from PQ_CACHE to totally free are not counted in the
1529 * pages_freed counter.
1531 * WARNING! Can be called from two pagedaemon threads simultaneously.
1534 vm_pageout_scan_cache(int avail_shortage
, int pass
,
1535 int vnodes_skipped
, int recycle_count
)
1537 static int lastkillticks
;
1538 struct vm_pageout_scan_info info
;
1542 isep
= (curthread
== emergpager
);
1544 while (vmstats
.v_free_count
<
1545 (vmstats
.v_free_min
+ vmstats
.v_free_target
) / 2) {
1547 * This steals some code from vm/vm_page.c
1549 static int cache_rover
= 0;
1551 m
= vm_page_list_find(PQ_CACHE
, cache_rover
& PQ_L2_MASK
);
1554 /* page is returned removed from its queue and spinlocked */
1555 if (vm_page_busy_try(m
, TRUE
)) {
1556 vm_page_deactivate_locked(m
);
1557 vm_page_spin_unlock(m
);
1560 vm_page_spin_unlock(m
);
1561 pagedaemon_wakeup();
1565 * Remaining operations run with the page busy and neither
1566 * the page or the queue will be spin-locked.
1568 if ((m
->flags
& (PG_UNMANAGED
| PG_NEED_COMMIT
)) ||
1571 vm_page_deactivate(m
);
1575 KKASSERT((m
->flags
& PG_MAPPED
) == 0);
1576 KKASSERT(m
->dirty
== 0);
1577 cache_rover
+= PQ_PRIME2
;
1578 vm_pageout_page_free(m
);
1579 mycpu
->gd_cnt
.v_dfree
++;
1582 #if !defined(NO_SWAPPING)
1584 * Idle process swapout -- run once per second.
1586 if (vm_swap_idle_enabled
) {
1588 if (time_uptime
!= lsec
) {
1589 atomic_set_int(&vm_pageout_req_swapout
, VM_SWAP_IDLE
);
1597 * If we didn't get enough free pages, and we have skipped a vnode
1598 * in a writeable object, wakeup the sync daemon. And kick swapout
1599 * if we did not get enough free pages.
1601 if (vm_paging_target() > 0) {
1602 if (vnodes_skipped
&& vm_page_count_min(0))
1603 speedup_syncer(NULL
);
1604 #if !defined(NO_SWAPPING)
1605 if (vm_swap_enabled
&& vm_page_count_target()) {
1606 atomic_set_int(&vm_pageout_req_swapout
, VM_SWAP_NORMAL
);
1613 * Handle catastrophic conditions. Under good conditions we should
1614 * be at the target, well beyond our minimum. If we could not even
1615 * reach our minimum the system is under heavy stress. But just being
1616 * under heavy stress does not trigger process killing.
1618 * We consider ourselves to have run out of memory if the swap pager
1619 * is full and avail_shortage is still positive. The secondary check
1620 * ensures that we do not kill processes if the instantanious
1621 * availability is good, even if the pageout demon pass says it
1622 * couldn't get to the target.
1624 * NOTE! THE EMERGENCY PAGER (isep) DOES NOT HANDLE SWAP FULL
1627 if (swap_pager_almost_full
&&
1630 (vm_page_count_min(recycle_count
) || avail_shortage
> 0)) {
1631 kprintf("Warning: system low on memory+swap "
1632 "shortage %d for %d ticks!\n",
1633 avail_shortage
, ticks
- swap_fail_ticks
);
1635 kprintf("Metrics: spaf=%d spf=%d pass=%d avail=%d target=%d last=%u\n",
1636 swap_pager_almost_full
,
1641 (unsigned int)(ticks
- lastkillticks
));
1643 if (swap_pager_full
&&
1646 avail_shortage
> 0 &&
1647 vm_paging_target() > 0 &&
1648 (unsigned int)(ticks
- lastkillticks
) >= hz
) {
1650 * Kill something, maximum rate once per second to give
1651 * the process time to free up sufficient memory.
1653 lastkillticks
= ticks
;
1654 info
.bigproc
= NULL
;
1656 allproc_scan(vm_pageout_scan_callback
, &info
, 0);
1657 if (info
.bigproc
!= NULL
) {
1658 kprintf("Try to kill process %d %s\n",
1659 info
.bigproc
->p_pid
, info
.bigproc
->p_comm
);
1660 info
.bigproc
->p_nice
= PRIO_MIN
;
1661 info
.bigproc
->p_usched
->resetpriority(
1662 FIRST_LWP_IN_PROC(info
.bigproc
));
1663 atomic_set_int(&info
.bigproc
->p_flags
, P_LOWMEMKILL
);
1664 killproc(info
.bigproc
, "out of swap space");
1665 wakeup(&vmstats
.v_free_count
);
1666 PRELE(info
.bigproc
);
1672 vm_pageout_scan_callback(struct proc
*p
, void *data
)
1674 struct vm_pageout_scan_info
*info
= data
;
1678 * Never kill system processes or init. If we have configured swap
1679 * then try to avoid killing low-numbered pids.
1681 if ((p
->p_flags
& P_SYSTEM
) || (p
->p_pid
== 1) ||
1682 ((p
->p_pid
< 48) && (vm_swap_size
!= 0))) {
1686 lwkt_gettoken(&p
->p_token
);
1689 * if the process is in a non-running type state,
1692 if (p
->p_stat
!= SACTIVE
&& p
->p_stat
!= SSTOP
&& p
->p_stat
!= SCORE
) {
1693 lwkt_reltoken(&p
->p_token
);
1698 * Get the approximate process size. Note that anonymous pages
1699 * with backing swap will be counted twice, but there should not
1700 * be too many such pages due to the stress the VM system is
1701 * under at this point.
1703 size
= vmspace_anonymous_count(p
->p_vmspace
) +
1704 vmspace_swap_count(p
->p_vmspace
);
1707 * If the this process is bigger than the biggest one
1710 if (info
->bigsize
< size
) {
1712 PRELE(info
->bigproc
);
1715 info
->bigsize
= size
;
1717 lwkt_reltoken(&p
->p_token
);
1724 * This routine tries to maintain the pseudo LRU active queue,
1725 * so that during long periods of time where there is no paging,
1726 * that some statistic accumulation still occurs. This code
1727 * helps the situation where paging just starts to occur.
1730 vm_pageout_page_stats(int q
)
1732 static int fullintervalcount
= 0;
1733 struct vm_page marker
;
1735 int pcount
, tpcount
; /* Number of pages to check */
1738 page_shortage
= (vmstats
.v_inactive_target
+ vmstats
.v_cache_max
+
1739 vmstats
.v_free_min
) -
1740 (vmstats
.v_free_count
+ vmstats
.v_inactive_count
+
1741 vmstats
.v_cache_count
);
1743 if (page_shortage
<= 0)
1746 pcount
= vm_page_queues
[PQ_ACTIVE
+ q
].lcnt
;
1747 fullintervalcount
+= vm_pageout_stats_interval
;
1748 if (fullintervalcount
< vm_pageout_full_stats_interval
) {
1749 tpcount
= (vm_pageout_stats_max
* pcount
) /
1750 vmstats
.v_page_count
+ 1;
1751 if (pcount
> tpcount
)
1754 fullintervalcount
= 0;
1757 bzero(&marker
, sizeof(marker
));
1758 marker
.flags
= PG_BUSY
| PG_FICTITIOUS
| PG_MARKER
;
1759 marker
.queue
= PQ_ACTIVE
+ q
;
1761 marker
.wire_count
= 1;
1763 vm_page_queues_spin_lock(PQ_ACTIVE
+ q
);
1764 TAILQ_INSERT_HEAD(&vm_page_queues
[PQ_ACTIVE
+ q
].pl
, &marker
, pageq
);
1767 * Queue locked at top of loop to avoid stack marker issues.
1769 while ((m
= TAILQ_NEXT(&marker
, pageq
)) != NULL
&&
1774 KKASSERT(m
->queue
== PQ_ACTIVE
+ q
);
1775 TAILQ_REMOVE(&vm_page_queues
[PQ_ACTIVE
+ q
].pl
, &marker
, pageq
);
1776 TAILQ_INSERT_AFTER(&vm_page_queues
[PQ_ACTIVE
+ q
].pl
, m
,
1780 * Skip marker pages (atomic against other markers to avoid
1781 * infinite hop-over scans).
1783 if (m
->flags
& PG_MARKER
)
1787 * Ignore pages we can't busy
1789 if (vm_page_busy_try(m
, TRUE
))
1793 * Remaining operations run with the page busy and neither
1794 * the page or the queue will be spin-locked.
1796 vm_page_queues_spin_unlock(PQ_ACTIVE
+ q
);
1797 KKASSERT(m
->queue
== PQ_ACTIVE
+ q
);
1800 * We now have a safely busied page, the page and queue
1801 * spinlocks have been released.
1805 if (m
->hold_count
) {
1811 * Calculate activity
1814 if (m
->flags
& PG_REFERENCED
) {
1815 vm_page_flag_clear(m
, PG_REFERENCED
);
1818 actcount
+= pmap_ts_referenced(m
);
1821 * Update act_count and move page to end of queue.
1824 m
->act_count
+= ACT_ADVANCE
+ actcount
;
1825 if (m
->act_count
> ACT_MAX
)
1826 m
->act_count
= ACT_MAX
;
1827 vm_page_and_queue_spin_lock(m
);
1828 if (m
->queue
- m
->pc
== PQ_ACTIVE
) {
1830 &vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1833 &vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1836 vm_page_and_queue_spin_unlock(m
);
1841 if (m
->act_count
== 0) {
1843 * We turn off page access, so that we have
1844 * more accurate RSS stats. We don't do this
1845 * in the normal page deactivation when the
1846 * system is loaded VM wise, because the
1847 * cost of the large number of page protect
1848 * operations would be higher than the value
1849 * of doing the operation.
1851 * We use the marker to save our place so
1852 * we can release the spin lock. both (m)
1853 * and (next) will be invalid.
1855 vm_page_protect(m
, VM_PROT_NONE
);
1856 vm_page_deactivate(m
);
1858 m
->act_count
-= min(m
->act_count
, ACT_DECLINE
);
1859 vm_page_and_queue_spin_lock(m
);
1860 if (m
->queue
- m
->pc
== PQ_ACTIVE
) {
1862 &vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1865 &vm_page_queues
[PQ_ACTIVE
+ q
].pl
,
1868 vm_page_and_queue_spin_unlock(m
);
1872 vm_page_queues_spin_lock(PQ_ACTIVE
+ q
);
1876 * Remove our local marker
1878 * Page queue still spin-locked.
1880 TAILQ_REMOVE(&vm_page_queues
[PQ_ACTIVE
+ q
].pl
, &marker
, pageq
);
1881 vm_page_queues_spin_unlock(PQ_ACTIVE
+ q
);
1885 vm_pageout_free_page_calc(vm_size_t count
)
1887 if (count
< vmstats
.v_page_count
)
1890 * free_reserved needs to include enough for the largest swap pager
1891 * structures plus enough for any pv_entry structs when paging.
1893 * v_free_min normal allocations
1894 * v_free_reserved system allocations
1895 * v_pageout_free_min allocations by pageout daemon
1896 * v_interrupt_free_min low level allocations (e.g swap structures)
1898 if (vmstats
.v_page_count
> 1024)
1899 vmstats
.v_free_min
= 64 + (vmstats
.v_page_count
- 1024) / 200;
1901 vmstats
.v_free_min
= 64;
1904 * Make sure the vmmeter slop can't blow out our global minimums.
1906 * However, to accomodate weird configurations (vkernels with many
1907 * cpus and little memory, or artifically reduced hw.physmem), do
1908 * not allow v_free_min to exceed 1/20 of ram or the pageout demon
1909 * will go out of control.
1911 if (vmstats
.v_free_min
< VMMETER_SLOP_COUNT
* ncpus
* 10)
1912 vmstats
.v_free_min
= VMMETER_SLOP_COUNT
* ncpus
* 10;
1913 if (vmstats
.v_free_min
> vmstats
.v_page_count
/ 20)
1914 vmstats
.v_free_min
= vmstats
.v_page_count
/ 20;
1916 vmstats
.v_free_reserved
= vmstats
.v_free_min
* 4 / 8 + 7;
1917 vmstats
.v_free_severe
= vmstats
.v_free_min
* 4 / 8 + 0;
1918 vmstats
.v_pageout_free_min
= vmstats
.v_free_min
* 2 / 8 + 7;
1919 vmstats
.v_interrupt_free_min
= vmstats
.v_free_min
* 1 / 8 + 7;
1926 * vm_pageout is the high level pageout daemon. TWO kernel threads run
1927 * this daemon, the primary pageout daemon and the emergency pageout daemon.
1929 * The emergency pageout daemon takes over when the primary pageout daemon
1930 * deadlocks. The emergency pageout daemon ONLY pages out to swap, thus
1931 * avoiding the many low-memory deadlocks which can occur when paging out
1935 vm_pageout_thread(void)
1944 curthread
->td_flags
|= TDF_SYSTHREAD
;
1947 * We only need to setup once.
1951 if (curthread
== emergpager
) {
1957 * Initialize some paging parameters.
1959 vm_pageout_free_page_calc(vmstats
.v_page_count
);
1962 * v_free_target and v_cache_min control pageout hysteresis. Note
1963 * that these are more a measure of the VM cache queue hysteresis
1964 * then the VM free queue. Specifically, v_free_target is the
1965 * high water mark (free+cache pages).
1967 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the
1968 * low water mark, while v_free_min is the stop. v_cache_min must
1969 * be big enough to handle memory needs while the pageout daemon
1970 * is signalled and run to free more pages.
1972 if (vmstats
.v_free_count
> 6144)
1973 vmstats
.v_free_target
= 4 * vmstats
.v_free_min
+
1974 vmstats
.v_free_reserved
;
1976 vmstats
.v_free_target
= 2 * vmstats
.v_free_min
+
1977 vmstats
.v_free_reserved
;
1980 * NOTE: With the new buffer cache b_act_count we want the default
1981 * inactive target to be a percentage of available memory.
1983 * The inactive target essentially determines the minimum
1984 * number of 'temporary' pages capable of caching one-time-use
1985 * files when the VM system is otherwise full of pages
1986 * belonging to multi-time-use files or active program data.
1988 * NOTE: The inactive target is aggressively persued only if the
1989 * inactive queue becomes too small. If the inactive queue
1990 * is large enough to satisfy page movement to free+cache
1991 * then it is repopulated more slowly from the active queue.
1992 * This allows a general inactive_target default to be set.
1994 * There is an issue here for processes which sit mostly idle
1995 * 'overnight', such as sshd, tcsh, and X. Any movement from
1996 * the active queue will eventually cause such pages to
1997 * recycle eventually causing a lot of paging in the morning.
1998 * To reduce the incidence of this pages cycled out of the
1999 * buffer cache are moved directly to the inactive queue if
2000 * they were only used once or twice.
2002 * The vfs.vm_cycle_point sysctl can be used to adjust this.
2003 * Increasing the value (up to 64) increases the number of
2004 * buffer recyclements which go directly to the inactive queue.
2006 if (vmstats
.v_free_count
> 2048) {
2007 vmstats
.v_cache_min
= vmstats
.v_free_target
;
2008 vmstats
.v_cache_max
= 2 * vmstats
.v_cache_min
;
2010 vmstats
.v_cache_min
= 0;
2011 vmstats
.v_cache_max
= 0;
2013 vmstats
.v_inactive_target
= vmstats
.v_free_count
/ 4;
2015 /* XXX does not really belong here */
2016 if (vm_page_max_wired
== 0)
2017 vm_page_max_wired
= vmstats
.v_free_count
/ 3;
2019 if (vm_pageout_stats_max
== 0)
2020 vm_pageout_stats_max
= vmstats
.v_free_target
;
2023 * Set interval in seconds for stats scan.
2025 if (vm_pageout_stats_interval
== 0)
2026 vm_pageout_stats_interval
= 5;
2027 if (vm_pageout_full_stats_interval
== 0)
2028 vm_pageout_full_stats_interval
= vm_pageout_stats_interval
* 4;
2032 * Set maximum free per pass
2034 if (vm_pageout_stats_free_max
== 0)
2035 vm_pageout_stats_free_max
= 5;
2037 swap_pager_swap_init();
2040 atomic_swap_int(&sequence_emerg_pager
, 1);
2041 wakeup(&sequence_emerg_pager
);
2045 * Sequence emergency pager startup
2048 while (sequence_emerg_pager
== 0)
2049 tsleep(&sequence_emerg_pager
, 0, "pstartup", hz
);
2053 * The pageout daemon is never done, so loop forever.
2055 * WARNING! This code is being executed by two kernel threads
2056 * potentially simultaneously.
2061 int inactive_shortage
;
2062 int vnodes_skipped
= 0;
2063 int recycle_count
= 0;
2067 * Wait for an action request. If we timeout check to
2068 * see if paging is needed (in case the normal wakeup
2073 * Emergency pagedaemon monitors the primary
2074 * pagedaemon while vm_pages_needed != 0.
2076 * The emergency pagedaemon only runs if VM paging
2077 * is needed and the primary pagedaemon has not
2078 * updated vm_pagedaemon_time for more than 2 seconds.
2080 if (vm_pages_needed
)
2081 tsleep(&vm_pagedaemon_time
, 0, "psleep", hz
);
2083 tsleep(&vm_pagedaemon_time
, 0, "psleep", hz
*10);
2084 if (vm_pages_needed
== 0) {
2088 if ((int)(ticks
- vm_pagedaemon_time
) < hz
* 2) {
2091 kprintf("Emergency pager finished\n");
2096 if (emrunning
== 0) {
2098 kprintf("Emergency pager running\n");
2102 * Primary pagedaemon
2104 if (vm_pages_needed
== 0) {
2105 error
= tsleep(&vm_pages_needed
,
2107 vm_pageout_stats_interval
* hz
);
2109 vm_paging_needed() == 0 &&
2110 vm_pages_needed
== 0) {
2111 for (q
= 0; q
< PQ_L2_SIZE
; ++q
)
2112 vm_pageout_page_stats(q
);
2115 vm_pagedaemon_time
= ticks
;
2116 vm_pages_needed
= 1;
2119 * Wake the emergency pagedaemon up so it
2120 * can monitor us. It will automatically
2121 * go back into a long sleep when
2122 * vm_pages_needed returns to 0.
2124 wakeup(&vm_pagedaemon_time
);
2128 mycpu
->gd_cnt
.v_pdwakeups
++;
2131 * Scan for INACTIVE->CLEAN/PAGEOUT
2133 * This routine tries to avoid thrashing the system with
2134 * unnecessary activity.
2136 * Calculate our target for the number of free+cache pages we
2137 * want to get to. This is higher then the number that causes
2138 * allocations to stall (severe) in order to provide hysteresis,
2139 * and if we don't make it all the way but get to the minimum
2140 * we're happy. Goose it a bit if there are multiple requests
2143 * Don't reduce avail_shortage inside the loop or the
2144 * PQAVERAGE() calculation will break.
2146 * NOTE! deficit is differentiated from avail_shortage as
2147 * REQUIRING at least (deficit) pages to be cleaned,
2148 * even if the page queues are in good shape. This
2149 * is used primarily for handling per-process
2150 * RLIMIT_RSS and may also see small values when
2151 * processes block due to low memory.
2155 vm_pagedaemon_time
= ticks
;
2156 avail_shortage
= vm_paging_target() + vm_pageout_deficit
;
2157 vm_pageout_deficit
= 0;
2159 if (avail_shortage
> 0) {
2162 for (q
= 0; q
< PQ_L2_SIZE
; ++q
) {
2163 delta
+= vm_pageout_scan_inactive(
2165 (q
+ q1iterator
) & PQ_L2_MASK
,
2166 PQAVERAGE(avail_shortage
),
2168 if (avail_shortage
- delta
<= 0)
2171 avail_shortage
-= delta
;
2176 * Figure out how many active pages we must deactivate. If
2177 * we were able to reach our target with just the inactive
2178 * scan above we limit the number of active pages we
2179 * deactivate to reduce unnecessary work.
2183 vm_pagedaemon_time
= ticks
;
2184 inactive_shortage
= vmstats
.v_inactive_target
-
2185 vmstats
.v_inactive_count
;
2188 * If we were unable to free sufficient inactive pages to
2189 * satisfy the free/cache queue requirements then simply
2190 * reaching the inactive target may not be good enough.
2191 * Try to deactivate pages in excess of the target based
2194 * However to prevent thrashing the VM system do not
2195 * deactivate more than an additional 1/10 the inactive
2196 * target's worth of active pages.
2198 if (avail_shortage
> 0) {
2199 tmp
= avail_shortage
* 2;
2200 if (tmp
> vmstats
.v_inactive_target
/ 10)
2201 tmp
= vmstats
.v_inactive_target
/ 10;
2202 inactive_shortage
+= tmp
;
2206 * Only trigger a pmap cleanup on inactive shortage.
2208 if (isep
== 0 && inactive_shortage
> 0) {
2213 * Scan for ACTIVE->INACTIVE
2215 * Only trigger on inactive shortage. Triggering on
2216 * avail_shortage can starve the active queue with
2217 * unnecessary active->inactive transitions and destroy
2220 * If this is the emergency pager, always try to move
2221 * a few pages from active to inactive because the inactive
2222 * queue might have enough pages, but not enough anonymous
2225 if (isep
&& inactive_shortage
< vm_emerg_launder
)
2226 inactive_shortage
= vm_emerg_launder
;
2228 if (/*avail_shortage > 0 ||*/ inactive_shortage
> 0) {
2231 for (q
= 0; q
< PQ_L2_SIZE
; ++q
) {
2232 delta
+= vm_pageout_scan_active(
2234 (q
+ q2iterator
) & PQ_L2_MASK
,
2235 PQAVERAGE(avail_shortage
),
2236 PQAVERAGE(inactive_shortage
),
2238 if (inactive_shortage
- delta
<= 0 &&
2239 avail_shortage
- delta
<= 0) {
2243 inactive_shortage
-= delta
;
2244 avail_shortage
-= delta
;
2249 * Scan for CACHE->FREE
2251 * Finally free enough cache pages to meet our free page
2252 * requirement and take more drastic measures if we are
2257 vm_pagedaemon_time
= ticks
;
2258 vm_pageout_scan_cache(avail_shortage
, pass
,
2259 vnodes_skipped
, recycle_count
);
2262 * Wait for more work.
2264 if (avail_shortage
> 0) {
2266 if (pass
< 10 && vm_pages_needed
> 1) {
2268 * Normal operation, additional processes
2269 * have already kicked us. Retry immediately
2270 * unless swap space is completely full in
2271 * which case delay a bit.
2273 if (swap_pager_full
) {
2274 tsleep(&vm_pages_needed
, 0, "pdelay",
2276 } /* else immediate retry */
2277 } else if (pass
< 10) {
2279 * Normal operation, fewer processes. Delay
2280 * a bit but allow wakeups. vm_pages_needed
2281 * is only adjusted against the primary
2285 vm_pages_needed
= 0;
2286 tsleep(&vm_pages_needed
, 0, "pdelay", hz
/ 10);
2288 vm_pages_needed
= 1;
2289 } else if (swap_pager_full
== 0) {
2291 * We've taken too many passes, forced delay.
2293 tsleep(&vm_pages_needed
, 0, "pdelay", hz
/ 10);
2296 * Running out of memory, catastrophic
2297 * back-off to one-second intervals.
2299 tsleep(&vm_pages_needed
, 0, "pdelay", hz
);
2301 } else if (vm_pages_needed
) {
2303 * Interlocked wakeup of waiters (non-optional).
2305 * Similar to vm_page_free_wakeup() in vm_page.c,
2309 if (!vm_page_count_min(vm_page_free_hysteresis
) ||
2310 !vm_page_count_target()) {
2311 vm_pages_needed
= 0;
2312 wakeup(&vmstats
.v_free_count
);
2320 static struct kproc_desc pg1_kp
= {
2325 SYSINIT(pagedaemon
, SI_SUB_KTHREAD_PAGE
, SI_ORDER_FIRST
, kproc_start
, &pg1_kp
);
2327 static struct kproc_desc pg2_kp
= {
2332 SYSINIT(emergpager
, SI_SUB_KTHREAD_PAGE
, SI_ORDER_ANY
, kproc_start
, &pg2_kp
);
2336 * Called after allocating a page out of the cache or free queue
2337 * to possibly wake the pagedaemon up to replentish our supply.
2339 * We try to generate some hysteresis by waking the pagedaemon up
2340 * when our free+cache pages go below the free_min+cache_min level.
2341 * The pagedaemon tries to get the count back up to at least the
2342 * minimum, and through to the target level if possible.
2344 * If the pagedaemon is already active bump vm_pages_needed as a hint
2345 * that there are even more requests pending.
2351 pagedaemon_wakeup(void)
2353 if (vm_paging_needed() && curthread
!= pagethread
) {
2354 if (vm_pages_needed
== 0) {
2355 vm_pages_needed
= 1; /* SMP race ok */
2356 wakeup(&vm_pages_needed
);
2357 } else if (vm_page_count_min(0)) {
2358 ++vm_pages_needed
; /* SMP race ok */
2363 #if !defined(NO_SWAPPING)
2370 vm_req_vmdaemon(void)
2372 static int lastrun
= 0;
2374 if ((ticks
> (lastrun
+ hz
)) || (ticks
< lastrun
)) {
2375 wakeup(&vm_daemon_needed
);
2380 static int vm_daemon_callback(struct proc
*p
, void *data __unused
);
2391 tsleep(&vm_daemon_needed
, 0, "psleep", 0);
2392 req_swapout
= atomic_swap_int(&vm_pageout_req_swapout
, 0);
2398 swapout_procs(vm_pageout_req_swapout
);
2401 * scan the processes for exceeding their rlimits or if
2402 * process is swapped out -- deactivate pages
2404 allproc_scan(vm_daemon_callback
, NULL
, 0);
2409 vm_daemon_callback(struct proc
*p
, void *data __unused
)
2412 vm_pindex_t limit
, size
;
2415 * if this is a system process or if we have already
2416 * looked at this process, skip it.
2418 lwkt_gettoken(&p
->p_token
);
2420 if (p
->p_flags
& (P_SYSTEM
| P_WEXIT
)) {
2421 lwkt_reltoken(&p
->p_token
);
2426 * if the process is in a non-running type state,
2429 if (p
->p_stat
!= SACTIVE
&& p
->p_stat
!= SSTOP
&& p
->p_stat
!= SCORE
) {
2430 lwkt_reltoken(&p
->p_token
);
2437 limit
= OFF_TO_IDX(qmin(p
->p_rlimit
[RLIMIT_RSS
].rlim_cur
,
2438 p
->p_rlimit
[RLIMIT_RSS
].rlim_max
));
2441 * let processes that are swapped out really be
2442 * swapped out. Set the limit to nothing to get as
2443 * many pages out to swap as possible.
2445 if (p
->p_flags
& P_SWAPPEDOUT
)
2450 size
= pmap_resident_tlnw_count(&vm
->vm_pmap
);
2451 if (limit
>= 0 && size
> 4096 &&
2452 size
- 4096 >= limit
&& vm_pageout_memuse_mode
>= 1) {
2453 vm_pageout_map_deactivate_pages(&vm
->vm_map
, limit
);
2457 lwkt_reltoken(&p
->p_token
);