devfs - Fix incorrect st_size reporting
[dragonfly.git] / sys / vm / vm_pageout.c
CommitLineData
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1/*
2 * Copyright (c) 1991 Regents of the University of California.
3 * All rights reserved.
4 * Copyright (c) 1994 John S. Dyson
5 * All rights reserved.
6 * Copyright (c) 1994 David Greenman
7 * All rights reserved.
8 *
9 * This code is derived from software contributed to Berkeley by
10 * The Mach Operating System project at Carnegie-Mellon University.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 *
40 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
41 *
42 *
43 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
44 * All rights reserved.
45 *
46 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
47 *
48 * Permission to use, copy, modify and distribute this software and
49 * its documentation is hereby granted, provided that both the copyright
50 * notice and this permission notice appear in all copies of the
51 * software, derivative works or modified versions, and any portions
52 * thereof, and that both notices appear in supporting documentation.
53 *
54 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
55 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
56 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
57 *
58 * Carnegie Mellon requests users of this software to return to
59 *
60 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
61 * School of Computer Science
62 * Carnegie Mellon University
63 * Pittsburgh PA 15213-3890
64 *
65 * any improvements or extensions that they make and grant Carnegie the
66 * rights to redistribute these changes.
67 *
68 * $FreeBSD: src/sys/vm/vm_pageout.c,v 1.151.2.15 2002/12/29 18:21:04 dillon Exp $
4ecf7cc9 69 * $DragonFly: src/sys/vm/vm_pageout.c,v 1.36 2008/07/01 02:02:56 dillon Exp $
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70 */
71
72/*
73 * The proverbial page-out daemon.
74 */
75
76#include "opt_vm.h"
77#include <sys/param.h>
78#include <sys/systm.h>
79#include <sys/kernel.h>
80#include <sys/proc.h>
81#include <sys/kthread.h>
82#include <sys/resourcevar.h>
83#include <sys/signalvar.h>
84#include <sys/vnode.h>
85#include <sys/vmmeter.h>
86#include <sys/sysctl.h>
87
88#include <vm/vm.h>
89#include <vm/vm_param.h>
90#include <sys/lock.h>
91#include <vm/vm_object.h>
92#include <vm/vm_page.h>
93#include <vm/vm_map.h>
94#include <vm/vm_pageout.h>
95#include <vm/vm_pager.h>
96#include <vm/swap_pager.h>
97#include <vm/vm_extern.h>
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98
99#include <sys/thread2.h>
12e4aaff 100#include <vm/vm_page2.h>
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101
102/*
103 * System initialization
104 */
105
106/* the kernel process "vm_pageout"*/
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107static void vm_pageout (void);
108static int vm_pageout_clean (vm_page_t);
20479584 109static int vm_pageout_scan (int pass);
1388df65 110static int vm_pageout_free_page_calc (vm_size_t count);
bc6dffab 111struct thread *pagethread;
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112
113static struct kproc_desc page_kp = {
114 "pagedaemon",
115 vm_pageout,
bc6dffab 116 &pagethread
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117};
118SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp)
119
120#if !defined(NO_SWAPPING)
121/* the kernel process "vm_daemon"*/
1388df65 122static void vm_daemon (void);
bc6dffab 123static struct thread *vmthread;
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124
125static struct kproc_desc vm_kp = {
126 "vmdaemon",
127 vm_daemon,
bc6dffab 128 &vmthread
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129};
130SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp)
131#endif
132
133
134int vm_pages_needed=0; /* Event on which pageout daemon sleeps */
135int vm_pageout_deficit=0; /* Estimated number of pages deficit */
136int vm_pageout_pages_needed=0; /* flag saying that the pageout daemon needs pages */
137
138#if !defined(NO_SWAPPING)
139static int vm_pageout_req_swapout; /* XXX */
140static int vm_daemon_needed;
141#endif
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142static int vm_max_launder = 32;
143static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0;
144static int vm_pageout_full_stats_interval = 0;
145static int vm_pageout_stats_free_max=0, vm_pageout_algorithm=0;
146static int defer_swap_pageouts=0;
147static int disable_swap_pageouts=0;
148
149#if defined(NO_SWAPPING)
150static int vm_swap_enabled=0;
151static int vm_swap_idle_enabled=0;
152#else
153static int vm_swap_enabled=1;
154static int vm_swap_idle_enabled=0;
155#endif
156
157SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm,
158 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt");
159
160SYSCTL_INT(_vm, OID_AUTO, max_launder,
161 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout");
162
163SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max,
164 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length");
165
166SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval,
167 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan");
168
169SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval,
170 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan");
171
172SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max,
173 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented");
174
175#if defined(NO_SWAPPING)
176SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
177 CTLFLAG_RD, &vm_swap_enabled, 0, "");
178SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
179 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "");
180#else
181SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
182 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout");
183SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
184 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
185#endif
186
187SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts,
188 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem");
189
190SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts,
191 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages");
192
193static int pageout_lock_miss;
194SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss,
195 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout");
196
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197int vm_load;
198SYSCTL_INT(_vm, OID_AUTO, vm_load,
199 CTLFLAG_RD, &vm_load, 0, "load on the VM system");
200int vm_load_enable = 1;
201SYSCTL_INT(_vm, OID_AUTO, vm_load_enable,
202 CTLFLAG_RW, &vm_load_enable, 0, "enable vm_load rate limiting");
203#ifdef INVARIANTS
204int vm_load_debug;
205SYSCTL_INT(_vm, OID_AUTO, vm_load_debug,
206 CTLFLAG_RW, &vm_load_debug, 0, "debug vm_load");
207#endif
208
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209#define VM_PAGEOUT_PAGE_COUNT 16
210int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
211
212int vm_page_max_wired; /* XXX max # of wired pages system-wide */
213
214#if !defined(NO_SWAPPING)
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215typedef void freeer_fcn_t (vm_map_t, vm_object_t, vm_pindex_t, int);
216static void vm_pageout_map_deactivate_pages (vm_map_t, vm_pindex_t);
984263bc 217static freeer_fcn_t vm_pageout_object_deactivate_pages;
1388df65 218static void vm_req_vmdaemon (void);
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219#endif
220static void vm_pageout_page_stats(void);
221
46311ac2 222/*
20479584 223 * Update vm_load to slow down faulting processes.
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224 */
225void
226vm_fault_ratecheck(void)
227{
228 if (vm_pages_needed) {
229 if (vm_load < 1000)
230 ++vm_load;
231 } else {
232 if (vm_load > 0)
233 --vm_load;
234 }
235}
236
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237/*
238 * vm_pageout_clean:
239 *
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240 * Clean the page and remove it from the laundry. The page must not be
241 * busy on-call.
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242 *
243 * We set the busy bit to cause potential page faults on this page to
244 * block. Note the careful timing, however, the busy bit isn't set till
245 * late and we cannot do anything that will mess with the page.
246 */
247
248static int
57e43348 249vm_pageout_clean(vm_page_t m)
984263bc 250{
5f910b2f 251 vm_object_t object;
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252 vm_page_t mc[2*vm_pageout_page_count];
253 int pageout_count;
254 int ib, is, page_base;
255 vm_pindex_t pindex = m->pindex;
256
257 object = m->object;
258
259 /*
260 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP
261 * with the new swapper, but we could have serious problems paging
262 * out other object types if there is insufficient memory.
263 *
264 * Unfortunately, checking free memory here is far too late, so the
265 * check has been moved up a procedural level.
266 */
267
268 /*
269 * Don't mess with the page if it's busy, held, or special
270 */
271 if ((m->hold_count != 0) ||
272 ((m->busy != 0) || (m->flags & (PG_BUSY|PG_UNMANAGED)))) {
273 return 0;
274 }
275
276 mc[vm_pageout_page_count] = m;
277 pageout_count = 1;
278 page_base = vm_pageout_page_count;
279 ib = 1;
280 is = 1;
281
282 /*
283 * Scan object for clusterable pages.
284 *
285 * We can cluster ONLY if: ->> the page is NOT
286 * clean, wired, busy, held, or mapped into a
287 * buffer, and one of the following:
288 * 1) The page is inactive, or a seldom used
289 * active page.
290 * -or-
291 * 2) we force the issue.
292 *
293 * During heavy mmap/modification loads the pageout
294 * daemon can really fragment the underlying file
295 * due to flushing pages out of order and not trying
296 * align the clusters (which leave sporatic out-of-order
297 * holes). To solve this problem we do the reverse scan
298 * first and attempt to align our cluster, then do a
299 * forward scan if room remains.
300 */
301
302more:
303 while (ib && pageout_count < vm_pageout_page_count) {
304 vm_page_t p;
305
306 if (ib > pindex) {
307 ib = 0;
308 break;
309 }
310
311 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) {
312 ib = 0;
313 break;
314 }
315 if (((p->queue - p->pc) == PQ_CACHE) ||
316 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) {
317 ib = 0;
318 break;
319 }
320 vm_page_test_dirty(p);
321 if ((p->dirty & p->valid) == 0 ||
322 p->queue != PQ_INACTIVE ||
323 p->wire_count != 0 || /* may be held by buf cache */
324 p->hold_count != 0) { /* may be undergoing I/O */
325 ib = 0;
326 break;
327 }
328 mc[--page_base] = p;
329 ++pageout_count;
330 ++ib;
331 /*
332 * alignment boundry, stop here and switch directions. Do
333 * not clear ib.
334 */
335 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0)
336 break;
337 }
338
339 while (pageout_count < vm_pageout_page_count &&
340 pindex + is < object->size) {
341 vm_page_t p;
342
343 if ((p = vm_page_lookup(object, pindex + is)) == NULL)
344 break;
345 if (((p->queue - p->pc) == PQ_CACHE) ||
346 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) {
347 break;
348 }
349 vm_page_test_dirty(p);
350 if ((p->dirty & p->valid) == 0 ||
351 p->queue != PQ_INACTIVE ||
352 p->wire_count != 0 || /* may be held by buf cache */
353 p->hold_count != 0) { /* may be undergoing I/O */
354 break;
355 }
356 mc[page_base + pageout_count] = p;
357 ++pageout_count;
358 ++is;
359 }
360
361 /*
362 * If we exhausted our forward scan, continue with the reverse scan
363 * when possible, even past a page boundry. This catches boundry
364 * conditions.
365 */
366 if (ib && pageout_count < vm_pageout_page_count)
367 goto more;
368
369 /*
370 * we allow reads during pageouts...
371 */
372 return vm_pageout_flush(&mc[page_base], pageout_count, 0);
373}
374
375/*
376 * vm_pageout_flush() - launder the given pages
377 *
378 * The given pages are laundered. Note that we setup for the start of
379 * I/O ( i.e. busy the page ), mark it read-only, and bump the object
380 * reference count all in here rather then in the parent. If we want
381 * the parent to do more sophisticated things we may have to change
382 * the ordering.
383 */
984263bc 384int
57e43348 385vm_pageout_flush(vm_page_t *mc, int count, int flags)
984263bc 386{
5f910b2f 387 vm_object_t object;
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388 int pageout_status[count];
389 int numpagedout = 0;
390 int i;
391
392 /*
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393 * Initiate I/O. Bump the vm_page_t->busy counter.
394 */
395 for (i = 0; i < count; i++) {
396 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count));
397 vm_page_io_start(mc[i]);
398 }
399
400 /*
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401 * We must make the pages read-only. This will also force the
402 * modified bit in the related pmaps to be cleared. The pager
403 * cannot clear the bit for us since the I/O completion code
404 * typically runs from an interrupt. The act of making the page
405 * read-only handles the case for us.
984263bc 406 */
984263bc 407 for (i = 0; i < count; i++) {
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408 vm_page_protect(mc[i], VM_PROT_READ);
409 }
410
411 object = mc[0]->object;
412 vm_object_pip_add(object, count);
413
414 vm_pager_put_pages(object, mc, count,
c439ad8f 415 (flags | ((object == &kernel_object) ? VM_PAGER_PUT_SYNC : 0)),
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416 pageout_status);
417
418 for (i = 0; i < count; i++) {
419 vm_page_t mt = mc[i];
420
421 switch (pageout_status[i]) {
422 case VM_PAGER_OK:
423 numpagedout++;
424 break;
425 case VM_PAGER_PEND:
426 numpagedout++;
427 break;
428 case VM_PAGER_BAD:
429 /*
430 * Page outside of range of object. Right now we
431 * essentially lose the changes by pretending it
432 * worked.
433 */
434 pmap_clear_modify(mt);
435 vm_page_undirty(mt);
436 break;
437 case VM_PAGER_ERROR:
438 case VM_PAGER_FAIL:
439 /*
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440 * A page typically cannot be paged out when we
441 * have run out of swap. We leave the page
442 * marked inactive and will try to page it out
443 * again later.
444 *
445 * Starvation of the active page list is used to
446 * determine when the system is massively memory
447 * starved.
984263bc 448 */
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449 break;
450 case VM_PAGER_AGAIN:
451 break;
452 }
453
454 /*
455 * If the operation is still going, leave the page busy to
456 * block all other accesses. Also, leave the paging in
457 * progress indicator set so that we don't attempt an object
458 * collapse.
93afe6be
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459 *
460 * For any pages which have completed synchronously,
461 * deactivate the page if we are under a severe deficit.
462 * Do not try to enter them into the cache, though, they
463 * might still be read-heavy.
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464 */
465 if (pageout_status[i] != VM_PAGER_PEND) {
466 vm_object_pip_wakeup(object);
467 vm_page_io_finish(mt);
93afe6be
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468 if (vm_page_count_severe())
469 vm_page_deactivate(mt);
470#if 0
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471 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt))
472 vm_page_protect(mt, VM_PROT_READ);
93afe6be 473#endif
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474 }
475 }
476 return numpagedout;
477}
478
479#if !defined(NO_SWAPPING)
480/*
481 * vm_pageout_object_deactivate_pages
482 *
483 * deactivate enough pages to satisfy the inactive target
484 * requirements or if vm_page_proc_limit is set, then
485 * deactivate all of the pages in the object and its
486 * backing_objects.
487 *
488 * The object and map must be locked.
489 */
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490static int vm_pageout_object_deactivate_pages_callback(vm_page_t, void *);
491
984263bc 492static void
57e43348 493vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object,
06ecca5a 494 vm_pindex_t desired, int map_remove_only)
984263bc 495{
1f804340 496 struct rb_vm_page_scan_info info;
984263bc 497 int remove_mode;
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498
499 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS)
500 return;
501
502 while (object) {
503 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
504 return;
505 if (object->paging_in_progress)
506 return;
507
508 remove_mode = map_remove_only;
509 if (object->shadow_count > 1)
510 remove_mode = 1;
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511
512 /*
513 * scan the objects entire memory queue. spl protection is
514 * required to avoid an interrupt unbusy/free race against
515 * our busy check.
516 */
5fd012e0 517 crit_enter();
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518 info.limit = remove_mode;
519 info.map = map;
520 info.desired = desired;
521 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL,
522 vm_pageout_object_deactivate_pages_callback,
523 &info
524 );
525 crit_exit();
526 object = object->backing_object;
527 }
528}
529
530static int
531vm_pageout_object_deactivate_pages_callback(vm_page_t p, void *data)
532{
533 struct rb_vm_page_scan_info *info = data;
534 int actcount;
984263bc 535
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536 if (pmap_resident_count(vm_map_pmap(info->map)) <= info->desired) {
537 return(-1);
538 }
539 mycpu->gd_cnt.v_pdpages++;
540 if (p->wire_count != 0 || p->hold_count != 0 || p->busy != 0 ||
541 (p->flags & (PG_BUSY|PG_UNMANAGED)) ||
542 !pmap_page_exists_quick(vm_map_pmap(info->map), p)) {
543 return(0);
544 }
984263bc 545
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546 actcount = pmap_ts_referenced(p);
547 if (actcount) {
548 vm_page_flag_set(p, PG_REFERENCED);
549 } else if (p->flags & PG_REFERENCED) {
550 actcount = 1;
551 }
552
553 if ((p->queue != PQ_ACTIVE) &&
554 (p->flags & PG_REFERENCED)) {
555 vm_page_activate(p);
556 p->act_count += actcount;
557 vm_page_flag_clear(p, PG_REFERENCED);
558 } else if (p->queue == PQ_ACTIVE) {
559 if ((p->flags & PG_REFERENCED) == 0) {
560 p->act_count -= min(p->act_count, ACT_DECLINE);
561 if (!info->limit && (vm_pageout_algorithm || (p->act_count == 0))) {
17cde63e 562 vm_page_busy(p);
984263bc 563 vm_page_protect(p, VM_PROT_NONE);
17cde63e 564 vm_page_wakeup(p);
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565 vm_page_deactivate(p);
566 } else {
567 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq);
568 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq);
984263bc 569 }
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570 } else {
571 vm_page_activate(p);
572 vm_page_flag_clear(p, PG_REFERENCED);
573 if (p->act_count < (ACT_MAX - ACT_ADVANCE))
574 p->act_count += ACT_ADVANCE;
575 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq);
576 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq);
984263bc 577 }
1f804340 578 } else if (p->queue == PQ_INACTIVE) {
17cde63e 579 vm_page_busy(p);
1f804340 580 vm_page_protect(p, VM_PROT_NONE);
17cde63e 581 vm_page_wakeup(p);
984263bc 582 }
1f804340 583 return(0);
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584}
585
586/*
587 * deactivate some number of pages in a map, try to do it fairly, but
588 * that is really hard to do.
589 */
590static void
57e43348 591vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired)
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592{
593 vm_map_entry_t tmpe;
594 vm_object_t obj, bigobj;
595 int nothingwired;
596
df4f70a6 597 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT)) {
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598 return;
599 }
600
601 bigobj = NULL;
602 nothingwired = TRUE;
603
604 /*
605 * first, search out the biggest object, and try to free pages from
606 * that.
607 */
608 tmpe = map->header.next;
609 while (tmpe != &map->header) {
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610 switch(tmpe->maptype) {
611 case VM_MAPTYPE_NORMAL:
612 case VM_MAPTYPE_VPAGETABLE:
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613 obj = tmpe->object.vm_object;
614 if ((obj != NULL) && (obj->shadow_count <= 1) &&
615 ((bigobj == NULL) ||
616 (bigobj->resident_page_count < obj->resident_page_count))) {
617 bigobj = obj;
618 }
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619 break;
620 default:
621 break;
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622 }
623 if (tmpe->wired_count > 0)
624 nothingwired = FALSE;
625 tmpe = tmpe->next;
626 }
627
628 if (bigobj)
629 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0);
630
631 /*
632 * Next, hunt around for other pages to deactivate. We actually
633 * do this search sort of wrong -- .text first is not the best idea.
634 */
635 tmpe = map->header.next;
636 while (tmpe != &map->header) {
637 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
638 break;
1b874851
MD
639 switch(tmpe->maptype) {
640 case VM_MAPTYPE_NORMAL:
641 case VM_MAPTYPE_VPAGETABLE:
984263bc
MD
642 obj = tmpe->object.vm_object;
643 if (obj)
644 vm_pageout_object_deactivate_pages(map, obj, desired, 0);
1b874851
MD
645 break;
646 default:
647 break;
984263bc
MD
648 }
649 tmpe = tmpe->next;
650 };
651
652 /*
653 * Remove all mappings if a process is swapped out, this will free page
654 * table pages.
655 */
656 if (desired == 0 && nothingwired)
657 pmap_remove(vm_map_pmap(map),
88181b08 658 VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS);
984263bc 659 vm_map_unlock(map);
984263bc
MD
660}
661#endif
662
663/*
a11aaa81
MD
664 * Don't try to be fancy - being fancy can lead to vnode deadlocks. We
665 * only do it for OBJT_DEFAULT and OBJT_SWAP objects which we know can
666 * be trivially freed.
984263bc 667 */
984263bc 668void
95813af0
MD
669vm_pageout_page_free(vm_page_t m)
670{
984263bc
MD
671 vm_object_t object = m->object;
672 int type = object->type;
673
674 if (type == OBJT_SWAP || type == OBJT_DEFAULT)
675 vm_object_reference(object);
676 vm_page_busy(m);
677 vm_page_protect(m, VM_PROT_NONE);
678 vm_page_free(m);
679 if (type == OBJT_SWAP || type == OBJT_DEFAULT)
680 vm_object_deallocate(object);
681}
682
683/*
20479584 684 * vm_pageout_scan does the dirty work for the pageout daemon.
984263bc 685 */
8fa76237
MD
686struct vm_pageout_scan_info {
687 struct proc *bigproc;
688 vm_offset_t bigsize;
689};
690
691static int vm_pageout_scan_callback(struct proc *p, void *data);
692
20479584 693static int
984263bc
MD
694vm_pageout_scan(int pass)
695{
8fa76237 696 struct vm_pageout_scan_info info;
984263bc
MD
697 vm_page_t m, next;
698 struct vm_page marker;
20479584
MD
699 int maxscan, pcount;
700 int recycle_count;
701 int inactive_shortage, active_shortage;
51db7ca2 702 int inactive_original_shortage;
984263bc
MD
703 vm_object_t object;
704 int actcount;
705 int vnodes_skipped = 0;
706 int maxlaunder;
984263bc
MD
707
708 /*
709 * Do whatever cleanup that the pmap code can.
710 */
711 pmap_collect();
712
984263bc 713 /*
20479584
MD
714 * Calculate our target for the number of free+cache pages we
715 * want to get to. This is higher then the number that causes
716 * allocations to stall (severe) in order to provide hysteresis,
717 * and if we don't make it all the way but get to the minimum
718 * we're happy.
984263bc 719 */
20479584 720 inactive_shortage = vm_paging_target() + vm_pageout_deficit;
51db7ca2 721 inactive_original_shortage = inactive_shortage;
20479584 722 vm_pageout_deficit = 0;
984263bc
MD
723
724 /*
725 * Initialize our marker
726 */
727 bzero(&marker, sizeof(marker));
728 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER;
729 marker.queue = PQ_INACTIVE;
730 marker.wire_count = 1;
731
732 /*
733 * Start scanning the inactive queue for pages we can move to the
734 * cache or free. The scan will stop when the target is reached or
735 * we have scanned the entire inactive queue. Note that m->act_count
736 * is not used to form decisions for the inactive queue, only for the
737 * active queue.
738 *
739 * maxlaunder limits the number of dirty pages we flush per scan.
740 * For most systems a smaller value (16 or 32) is more robust under
741 * extreme memory and disk pressure because any unnecessary writes
742 * to disk can result in extreme performance degredation. However,
743 * systems with excessive dirty pages (especially when MAP_NOSYNC is
744 * used) will die horribly with limited laundering. If the pageout
745 * daemon cannot clean enough pages in the first pass, we let it go
746 * all out in succeeding passes.
747 */
748 if ((maxlaunder = vm_max_launder) <= 1)
749 maxlaunder = 1;
750 if (pass)
751 maxlaunder = 10000;
752
06ecca5a 753 /*
5fd012e0
MD
754 * We will generally be in a critical section throughout the
755 * scan, but we can release it temporarily when we are sitting on a
756 * non-busy page without fear. this is required to prevent an
757 * interrupt from unbusying or freeing a page prior to our busy
758 * check, leaving us on the wrong queue or checking the wrong
759 * page.
06ecca5a 760 */
5fd012e0 761 crit_enter();
984263bc 762rescan0:
12e4aaff 763 maxscan = vmstats.v_inactive_count;
984263bc 764 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl);
20479584 765 m != NULL && maxscan-- > 0 && inactive_shortage > 0;
06ecca5a
MD
766 m = next
767 ) {
12e4aaff 768 mycpu->gd_cnt.v_pdpages++;
984263bc 769
06ecca5a
MD
770 /*
771 * Give interrupts a chance
772 */
5fd012e0
MD
773 crit_exit();
774 crit_enter();
984263bc 775
06ecca5a
MD
776 /*
777 * It's easier for some of the conditions below to just loop
778 * and catch queue changes here rather then check everywhere
779 * else.
780 */
781 if (m->queue != PQ_INACTIVE)
782 goto rescan0;
984263bc
MD
783 next = TAILQ_NEXT(m, pageq);
784
785 /*
786 * skip marker pages
787 */
788 if (m->flags & PG_MARKER)
789 continue;
790
791 /*
792 * A held page may be undergoing I/O, so skip it.
793 */
794 if (m->hold_count) {
984263bc
MD
795 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
796 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
e527fb6b 797 ++vm_swapcache_inactive_heuristic;
984263bc
MD
798 continue;
799 }
06ecca5a 800
984263bc
MD
801 /*
802 * Dont mess with busy pages, keep in the front of the
803 * queue, most likely are being paged out.
804 */
805 if (m->busy || (m->flags & PG_BUSY)) {
984263bc
MD
806 continue;
807 }
808
984263bc 809 if (m->object->ref_count == 0) {
06ecca5a
MD
810 /*
811 * If the object is not being used, we ignore previous
812 * references.
813 */
984263bc
MD
814 vm_page_flag_clear(m, PG_REFERENCED);
815 pmap_clear_reference(m);
816
984263bc 817 } else if (((m->flags & PG_REFERENCED) == 0) &&
06ecca5a
MD
818 (actcount = pmap_ts_referenced(m))) {
819 /*
820 * Otherwise, if the page has been referenced while
821 * in the inactive queue, we bump the "activation
822 * count" upwards, making it less likely that the
823 * page will be added back to the inactive queue
824 * prematurely again. Here we check the page tables
825 * (or emulated bits, if any), given the upper level
826 * VM system not knowing anything about existing
827 * references.
828 */
984263bc
MD
829 vm_page_activate(m);
830 m->act_count += (actcount + ACT_ADVANCE);
831 continue;
832 }
833
834 /*
835 * If the upper level VM system knows about any page
836 * references, we activate the page. We also set the
837 * "activation count" higher than normal so that we will less
838 * likely place pages back onto the inactive queue again.
839 */
840 if ((m->flags & PG_REFERENCED) != 0) {
841 vm_page_flag_clear(m, PG_REFERENCED);
842 actcount = pmap_ts_referenced(m);
843 vm_page_activate(m);
844 m->act_count += (actcount + ACT_ADVANCE + 1);
845 continue;
846 }
847
848 /*
849 * If the upper level VM system doesn't know anything about
850 * the page being dirty, we have to check for it again. As
851 * far as the VM code knows, any partially dirty pages are
852 * fully dirty.
41a01a4d
MD
853 *
854 * Pages marked PG_WRITEABLE may be mapped into the user
855 * address space of a process running on another cpu. A
856 * user process (without holding the MP lock) running on
857 * another cpu may be able to touch the page while we are
17cde63e
MD
858 * trying to remove it. vm_page_cache() will handle this
859 * case for us.
984263bc
MD
860 */
861 if (m->dirty == 0) {
862 vm_page_test_dirty(m);
863 } else {
864 vm_page_dirty(m);
865 }
866
984263bc 867 if (m->valid == 0) {
41a01a4d
MD
868 /*
869 * Invalid pages can be easily freed
870 */
984263bc 871 vm_pageout_page_free(m);
12e4aaff 872 mycpu->gd_cnt.v_dfree++;
20479584 873 --inactive_shortage;
984263bc
MD
874 } else if (m->dirty == 0) {
875 /*
41a01a4d
MD
876 * Clean pages can be placed onto the cache queue.
877 * This effectively frees them.
984263bc
MD
878 */
879 vm_page_cache(m);
20479584 880 --inactive_shortage;
984263bc
MD
881 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) {
882 /*
883 * Dirty pages need to be paged out, but flushing
884 * a page is extremely expensive verses freeing
885 * a clean page. Rather then artificially limiting
886 * the number of pages we can flush, we instead give
887 * dirty pages extra priority on the inactive queue
888 * by forcing them to be cycled through the queue
889 * twice before being flushed, after which the
890 * (now clean) page will cycle through once more
891 * before being freed. This significantly extends
892 * the thrash point for a heavily loaded machine.
893 */
984263bc
MD
894 vm_page_flag_set(m, PG_WINATCFLS);
895 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
896 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
e527fb6b 897 ++vm_swapcache_inactive_heuristic;
984263bc
MD
898 } else if (maxlaunder > 0) {
899 /*
900 * We always want to try to flush some dirty pages if
901 * we encounter them, to keep the system stable.
902 * Normally this number is small, but under extreme
903 * pressure where there are insufficient clean pages
904 * on the inactive queue, we may have to go all out.
905 */
906 int swap_pageouts_ok;
907 struct vnode *vp = NULL;
908
909 object = m->object;
910
911 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) {
912 swap_pageouts_ok = 1;
913 } else {
914 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts);
915 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts &&
20479584 916 vm_page_count_min(0));
984263bc
MD
917
918 }
919
920 /*
921 * We don't bother paging objects that are "dead".
922 * Those objects are in a "rundown" state.
923 */
924 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
984263bc
MD
925 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
926 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
e527fb6b 927 ++vm_swapcache_inactive_heuristic;
984263bc
MD
928 continue;
929 }
930
931 /*
932 * The object is already known NOT to be dead. It
933 * is possible for the vget() to block the whole
934 * pageout daemon, but the new low-memory handling
935 * code should prevent it.
936 *
937 * The previous code skipped locked vnodes and, worse,
938 * reordered pages in the queue. This results in
939 * completely non-deterministic operation because,
940 * quite often, a vm_fault has initiated an I/O and
941 * is holding a locked vnode at just the point where
942 * the pageout daemon is woken up.
943 *
944 * We can't wait forever for the vnode lock, we might
945 * deadlock due to a vn_read() getting stuck in
946 * vm_wait while holding this vnode. We skip the
947 * vnode if we can't get it in a reasonable amount
948 * of time.
949 */
950
951 if (object->type == OBJT_VNODE) {
952 vp = object->handle;
953
87de5057 954 if (vget(vp, LK_EXCLUSIVE|LK_NOOBJ|LK_TIMELOCK)) {
984263bc
MD
955 ++pageout_lock_miss;
956 if (object->flags & OBJ_MIGHTBEDIRTY)
957 vnodes_skipped++;
958 continue;
959 }
960
961 /*
962 * The page might have been moved to another
963 * queue during potential blocking in vget()
964 * above. The page might have been freed and
965 * reused for another vnode. The object might
966 * have been reused for another vnode.
967 */
968 if (m->queue != PQ_INACTIVE ||
969 m->object != object ||
970 object->handle != vp) {
971 if (object->flags & OBJ_MIGHTBEDIRTY)
972 vnodes_skipped++;
973 vput(vp);
974 continue;
975 }
976
977 /*
978 * The page may have been busied during the
979 * blocking in vput(); We don't move the
980 * page back onto the end of the queue so that
981 * statistics are more correct if we don't.
982 */
983 if (m->busy || (m->flags & PG_BUSY)) {
984 vput(vp);
985 continue;
986 }
987
988 /*
989 * If the page has become held it might
990 * be undergoing I/O, so skip it
991 */
992 if (m->hold_count) {
984263bc
MD
993 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
994 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
e527fb6b 995 ++vm_swapcache_inactive_heuristic;
984263bc
MD
996 if (object->flags & OBJ_MIGHTBEDIRTY)
997 vnodes_skipped++;
998 vput(vp);
999 continue;
1000 }
1001 }
1002
1003 /*
1004 * If a page is dirty, then it is either being washed
1005 * (but not yet cleaned) or it is still in the
1006 * laundry. If it is still in the laundry, then we
1007 * start the cleaning operation.
1008 *
1009 * This operation may cluster, invalidating the 'next'
1010 * pointer. To prevent an inordinate number of
1011 * restarts we use our marker to remember our place.
1012 *
20479584
MD
1013 * decrement inactive_shortage on success to account
1014 * for the (future) cleaned page. Otherwise we
1015 * could wind up laundering or cleaning too many
1016 * pages.
984263bc 1017 */
984263bc 1018 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq);
984263bc 1019 if (vm_pageout_clean(m) != 0) {
20479584 1020 --inactive_shortage;
984263bc 1021 --maxlaunder;
c84c24da 1022 }
984263bc
MD
1023 next = TAILQ_NEXT(&marker, pageq);
1024 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq);
984263bc
MD
1025 if (vp != NULL)
1026 vput(vp);
1027 }
1028 }
1029
1030 /*
20479584
MD
1031 * We want to move pages from the active queue to the inactive
1032 * queue to get the inactive queue to the inactive target. If
1033 * we still have a page shortage from above we try to directly free
1034 * clean pages instead of moving them.
06ecca5a 1035 *
20479584
MD
1036 * If we do still have a shortage we keep track of the number of
1037 * pages we free or cache (recycle_count) as a measure of thrashing
1038 * between the active and inactive queues.
1039 *
51db7ca2
MD
1040 * If we were able to completely satisfy the free+cache targets
1041 * from the inactive pool we limit the number of pages we move
1042 * from the active pool to the inactive pool to 2x the pages we
e6e9a0c3
MD
1043 * had removed from the inactive pool (with a minimum of 1/5 the
1044 * inactive target). If we were not able to completely satisfy
1045 * the free+cache targets we go for the whole target aggressively.
20479584
MD
1046 *
1047 * NOTE: Both variables can end up negative.
1048 * NOTE: We are still in a critical section.
984263bc 1049 */
20479584 1050 active_shortage = vmstats.v_inactive_target - vmstats.v_inactive_count;
e6e9a0c3
MD
1051 if (inactive_original_shortage < vmstats.v_inactive_target / 10)
1052 inactive_original_shortage = vmstats.v_inactive_target / 10;
51db7ca2
MD
1053 if (inactive_shortage <= 0 &&
1054 active_shortage > inactive_original_shortage * 2) {
1055 active_shortage = inactive_original_shortage * 2;
1056 }
20479584 1057
12e4aaff 1058 pcount = vmstats.v_active_count;
20479584 1059 recycle_count = 0;
984263bc
MD
1060 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1061
20479584
MD
1062 while ((m != NULL) && (pcount-- > 0) &&
1063 (inactive_shortage > 0 || active_shortage > 0)
1064 ) {
06ecca5a
MD
1065 /*
1066 * Give interrupts a chance.
1067 */
5fd012e0
MD
1068 crit_exit();
1069 crit_enter();
984263bc
MD
1070
1071 /*
06ecca5a 1072 * If the page was ripped out from under us, just stop.
984263bc 1073 */
06ecca5a 1074 if (m->queue != PQ_ACTIVE)
984263bc 1075 break;
984263bc 1076 next = TAILQ_NEXT(m, pageq);
06ecca5a 1077
984263bc
MD
1078 /*
1079 * Don't deactivate pages that are busy.
1080 */
1081 if ((m->busy != 0) ||
1082 (m->flags & PG_BUSY) ||
1083 (m->hold_count != 0)) {
984263bc
MD
1084 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1085 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1086 m = next;
1087 continue;
1088 }
1089
1090 /*
1091 * The count for pagedaemon pages is done after checking the
1092 * page for eligibility...
1093 */
12e4aaff 1094 mycpu->gd_cnt.v_pdpages++;
984263bc
MD
1095
1096 /*
20479584
MD
1097 * Check to see "how much" the page has been used and clear
1098 * the tracking access bits. If the object has no references
1099 * don't bother paying the expense.
984263bc
MD
1100 */
1101 actcount = 0;
1102 if (m->object->ref_count != 0) {
20479584
MD
1103 if (m->flags & PG_REFERENCED)
1104 ++actcount;
984263bc
MD
1105 actcount += pmap_ts_referenced(m);
1106 if (actcount) {
1107 m->act_count += ACT_ADVANCE + actcount;
1108 if (m->act_count > ACT_MAX)
1109 m->act_count = ACT_MAX;
1110 }
1111 }
984263bc
MD
1112 vm_page_flag_clear(m, PG_REFERENCED);
1113
1114 /*
20479584 1115 * actcount is only valid if the object ref_count is non-zero.
984263bc 1116 */
20479584 1117 if (actcount && m->object->ref_count != 0) {
984263bc
MD
1118 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1119 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1120 } else {
1121 m->act_count -= min(m->act_count, ACT_DECLINE);
1122 if (vm_pageout_algorithm ||
1123 m->object->ref_count == 0 ||
20479584
MD
1124 m->act_count < pass + 1
1125 ) {
1126 /*
1127 * Deactivate the page. If we had a
1128 * shortage from our inactive scan try to
1129 * free (cache) the page instead.
e6e9a0c3
MD
1130 *
1131 * Don't just blindly cache the page if
1132 * we do not have a shortage from the
1133 * inactive scan, that could lead to
1134 * gigabytes being moved.
20479584
MD
1135 */
1136 --active_shortage;
1137 if (inactive_shortage > 0 ||
1138 m->object->ref_count == 0) {
1139 if (inactive_shortage > 0)
1140 ++recycle_count;
17cde63e 1141 vm_page_busy(m);
984263bc 1142 vm_page_protect(m, VM_PROT_NONE);
17cde63e 1143 vm_page_wakeup(m);
e6e9a0c3
MD
1144 if (m->dirty == 0 &&
1145 inactive_shortage > 0) {
20479584 1146 --inactive_shortage;
984263bc 1147 vm_page_cache(m);
c84c24da 1148 } else {
984263bc 1149 vm_page_deactivate(m);
c84c24da 1150 }
984263bc
MD
1151 } else {
1152 vm_page_deactivate(m);
1153 }
1154 } else {
984263bc
MD
1155 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1156 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1157 }
1158 }
1159 m = next;
1160 }
1161
984263bc
MD
1162 /*
1163 * We try to maintain some *really* free pages, this allows interrupt
1164 * code to be guaranteed space. Since both cache and free queues
1165 * are considered basically 'free', moving pages from cache to free
1166 * does not effect other calculations.
06ecca5a 1167 *
5fd012e0 1168 * NOTE: we are still in a critical section.
c84c24da
MD
1169 *
1170 * Pages moved from PQ_CACHE to totally free are not counted in the
1171 * pages_freed counter.
984263bc 1172 */
12e4aaff 1173 while (vmstats.v_free_count < vmstats.v_free_reserved) {
984263bc
MD
1174 static int cache_rover = 0;
1175 m = vm_page_list_find(PQ_CACHE, cache_rover, FALSE);
20479584 1176 if (m == NULL)
984263bc
MD
1177 break;
1178 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) ||
1179 m->busy ||
1180 m->hold_count ||
1181 m->wire_count) {
1182#ifdef INVARIANTS
086c1d7e 1183 kprintf("Warning: busy page %p found in cache\n", m);
984263bc
MD
1184#endif
1185 vm_page_deactivate(m);
1186 continue;
1187 }
17cde63e
MD
1188 KKASSERT((m->flags & PG_MAPPED) == 0);
1189 KKASSERT(m->dirty == 0);
984263bc
MD
1190 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK;
1191 vm_pageout_page_free(m);
12e4aaff 1192 mycpu->gd_cnt.v_dfree++;
984263bc 1193 }
06ecca5a 1194
5fd012e0 1195 crit_exit();
984263bc
MD
1196
1197#if !defined(NO_SWAPPING)
1198 /*
1199 * Idle process swapout -- run once per second.
1200 */
1201 if (vm_swap_idle_enabled) {
1202 static long lsec;
1203 if (time_second != lsec) {
1204 vm_pageout_req_swapout |= VM_SWAP_IDLE;
1205 vm_req_vmdaemon();
1206 lsec = time_second;
1207 }
1208 }
1209#endif
1210
1211 /*
1212 * If we didn't get enough free pages, and we have skipped a vnode
1213 * in a writeable object, wakeup the sync daemon. And kick swapout
1214 * if we did not get enough free pages.
1215 */
1216 if (vm_paging_target() > 0) {
20479584 1217 if (vnodes_skipped && vm_page_count_min(0))
418ff780 1218 speedup_syncer();
984263bc
MD
1219#if !defined(NO_SWAPPING)
1220 if (vm_swap_enabled && vm_page_count_target()) {
1221 vm_req_vmdaemon();
1222 vm_pageout_req_swapout |= VM_SWAP_NORMAL;
1223 }
1224#endif
1225 }
1226
1227 /*
20479584
MD
1228 * Handle catastrophic conditions. Under good conditions we should
1229 * be at the target, well beyond our minimum. If we could not even
1230 * reach our minimum the system is under heavy stress.
1231 *
1232 * Determine whether we have run out of memory. This occurs when
1233 * swap_pager_full is TRUE and the only pages left in the page
1234 * queues are dirty. We will still likely have page shortages.
c84c24da
MD
1235 *
1236 * - swap_pager_full is set if insufficient swap was
1237 * available to satisfy a requested pageout.
1238 *
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MD
1239 * - the inactive queue is bloated (4 x size of active queue),
1240 * meaning it is unable to get rid of dirty pages and.
c84c24da 1241 *
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MD
1242 * - vm_page_count_min() without counting pages recycled from the
1243 * active queue (recycle_count) means we could not recover
1244 * enough pages to meet bare minimum needs. This test only
1245 * works if the inactive queue is bloated.
c84c24da 1246 *
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MD
1247 * - due to a positive inactive_shortage we shifted the remaining
1248 * dirty pages from the active queue to the inactive queue
1249 * trying to find clean ones to free.
984263bc 1250 */
20479584 1251 if (swap_pager_full && vm_page_count_min(recycle_count))
c84c24da 1252 kprintf("Warning: system low on memory+swap!\n");
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1253 if (swap_pager_full && vm_page_count_min(recycle_count) &&
1254 vmstats.v_inactive_count > vmstats.v_active_count * 4 &&
1255 inactive_shortage > 0) {
1256 /*
1257 * Kill something.
1258 */
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1259 info.bigproc = NULL;
1260 info.bigsize = 0;
1261 allproc_scan(vm_pageout_scan_callback, &info);
1262 if (info.bigproc != NULL) {
1263 killproc(info.bigproc, "out of swap space");
1264 info.bigproc->p_nice = PRIO_MIN;
08f2f1bb
SS
1265 info.bigproc->p_usched->resetpriority(
1266 FIRST_LWP_IN_PROC(info.bigproc));
12e4aaff 1267 wakeup(&vmstats.v_free_count);
8fa76237 1268 PRELE(info.bigproc);
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MD
1269 }
1270 }
20479584 1271 return(inactive_shortage);
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1272}
1273
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1274static int
1275vm_pageout_scan_callback(struct proc *p, void *data)
1276{
1277 struct vm_pageout_scan_info *info = data;
1278 vm_offset_t size;
1279
1280 /*
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MD
1281 * Never kill system processes or init. If we have configured swap
1282 * then try to avoid killing low-numbered pids.
8fa76237
MD
1283 */
1284 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) ||
1285 ((p->p_pid < 48) && (vm_swap_size != 0))) {
1286 return (0);
1287 }
1288
1289 /*
1290 * if the process is in a non-running type state,
1291 * don't touch it.
1292 */
20479584 1293 if (p->p_stat != SACTIVE && p->p_stat != SSTOP)
8fa76237 1294 return (0);
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1295
1296 /*
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1297 * Get the approximate process size. Note that anonymous pages
1298 * with backing swap will be counted twice, but there should not
1299 * be too many such pages due to the stress the VM system is
1300 * under at this point.
8fa76237 1301 */
20479584 1302 size = vmspace_anonymous_count(p->p_vmspace) +
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MD
1303 vmspace_swap_count(p->p_vmspace);
1304
1305 /*
1306 * If the this process is bigger than the biggest one
1307 * remember it.
1308 */
20479584 1309 if (info->bigsize < size) {
8fa76237
MD
1310 if (info->bigproc)
1311 PRELE(info->bigproc);
1312 PHOLD(p);
1313 info->bigproc = p;
1314 info->bigsize = size;
1315 }
1316 return(0);
1317}
1318
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1319/*
1320 * This routine tries to maintain the pseudo LRU active queue,
1321 * so that during long periods of time where there is no paging,
1322 * that some statistic accumulation still occurs. This code
1323 * helps the situation where paging just starts to occur.
1324 */
1325static void
57e43348 1326vm_pageout_page_stats(void)
984263bc 1327{
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MD
1328 vm_page_t m,next;
1329 int pcount,tpcount; /* Number of pages to check */
1330 static int fullintervalcount = 0;
1331 int page_shortage;
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1332
1333 page_shortage =
12e4aaff
MD
1334 (vmstats.v_inactive_target + vmstats.v_cache_max + vmstats.v_free_min) -
1335 (vmstats.v_free_count + vmstats.v_inactive_count + vmstats.v_cache_count);
984263bc
MD
1336
1337 if (page_shortage <= 0)
1338 return;
1339
5fd012e0 1340 crit_enter();
984263bc 1341
12e4aaff 1342 pcount = vmstats.v_active_count;
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MD
1343 fullintervalcount += vm_pageout_stats_interval;
1344 if (fullintervalcount < vm_pageout_full_stats_interval) {
12e4aaff 1345 tpcount = (vm_pageout_stats_max * vmstats.v_active_count) / vmstats.v_page_count;
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1346 if (pcount > tpcount)
1347 pcount = tpcount;
1348 } else {
1349 fullintervalcount = 0;
1350 }
1351
1352 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1353 while ((m != NULL) && (pcount-- > 0)) {
1354 int actcount;
1355
1356 if (m->queue != PQ_ACTIVE) {
1357 break;
1358 }
1359
1360 next = TAILQ_NEXT(m, pageq);
1361 /*
1362 * Don't deactivate pages that are busy.
1363 */
1364 if ((m->busy != 0) ||
1365 (m->flags & PG_BUSY) ||
1366 (m->hold_count != 0)) {
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MD
1367 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1368 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
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MD
1369 m = next;
1370 continue;
1371 }
1372
1373 actcount = 0;
1374 if (m->flags & PG_REFERENCED) {
1375 vm_page_flag_clear(m, PG_REFERENCED);
1376 actcount += 1;
1377 }
1378
1379 actcount += pmap_ts_referenced(m);
1380 if (actcount) {
1381 m->act_count += ACT_ADVANCE + actcount;
1382 if (m->act_count > ACT_MAX)
1383 m->act_count = ACT_MAX;
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MD
1384 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1385 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1386 } else {
1387 if (m->act_count == 0) {
1388 /*
1389 * We turn off page access, so that we have
1390 * more accurate RSS stats. We don't do this
1391 * in the normal page deactivation when the
1392 * system is loaded VM wise, because the
1393 * cost of the large number of page protect
1394 * operations would be higher than the value
1395 * of doing the operation.
1396 */
17cde63e 1397 vm_page_busy(m);
984263bc 1398 vm_page_protect(m, VM_PROT_NONE);
17cde63e 1399 vm_page_wakeup(m);
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MD
1400 vm_page_deactivate(m);
1401 } else {
1402 m->act_count -= min(m->act_count, ACT_DECLINE);
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MD
1403 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1404 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1405 }
1406 }
1407
1408 m = next;
1409 }
5fd012e0 1410 crit_exit();
984263bc
MD
1411}
1412
1413static int
57e43348 1414vm_pageout_free_page_calc(vm_size_t count)
984263bc 1415{
12e4aaff 1416 if (count < vmstats.v_page_count)
984263bc
MD
1417 return 0;
1418 /*
1419 * free_reserved needs to include enough for the largest swap pager
1420 * structures plus enough for any pv_entry structs when paging.
1421 */
12e4aaff
MD
1422 if (vmstats.v_page_count > 1024)
1423 vmstats.v_free_min = 4 + (vmstats.v_page_count - 1024) / 200;
984263bc 1424 else
12e4aaff
MD
1425 vmstats.v_free_min = 4;
1426 vmstats.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE +
1427 vmstats.v_interrupt_free_min;
1428 vmstats.v_free_reserved = vm_pageout_page_count +
1429 vmstats.v_pageout_free_min + (count / 768) + PQ_L2_SIZE;
1430 vmstats.v_free_severe = vmstats.v_free_min / 2;
1431 vmstats.v_free_min += vmstats.v_free_reserved;
1432 vmstats.v_free_severe += vmstats.v_free_reserved;
984263bc
MD
1433 return 1;
1434}
1435
1436
1437/*
20479584 1438 * vm_pageout is the high level pageout daemon.
984263bc
MD
1439 */
1440static void
57e43348 1441vm_pageout(void)
984263bc
MD
1442{
1443 int pass;
20479584 1444 int inactive_shortage;
984263bc
MD
1445
1446 /*
1447 * Initialize some paging parameters.
1448 */
4ecf7cc9 1449 curthread->td_flags |= TDF_SYSTHREAD;
984263bc 1450
12e4aaff
MD
1451 vmstats.v_interrupt_free_min = 2;
1452 if (vmstats.v_page_count < 2000)
984263bc
MD
1453 vm_pageout_page_count = 8;
1454
12e4aaff 1455 vm_pageout_free_page_calc(vmstats.v_page_count);
20479584 1456
984263bc
MD
1457 /*
1458 * v_free_target and v_cache_min control pageout hysteresis. Note
1459 * that these are more a measure of the VM cache queue hysteresis
1460 * then the VM free queue. Specifically, v_free_target is the
1461 * high water mark (free+cache pages).
1462 *
1463 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the
1464 * low water mark, while v_free_min is the stop. v_cache_min must
1465 * be big enough to handle memory needs while the pageout daemon
1466 * is signalled and run to free more pages.
1467 */
12e4aaff
MD
1468 if (vmstats.v_free_count > 6144)
1469 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved;
984263bc 1470 else
12e4aaff 1471 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved;
984263bc 1472
0e8bd897
MD
1473 /*
1474 * NOTE: With the new buffer cache b_act_count we want the default
1475 * inactive target to be a percentage of available memory.
1476 *
1477 * The inactive target essentially determines the minimum
1478 * number of 'temporary' pages capable of caching one-time-use
1479 * files when the VM system is otherwise full of pages
1480 * belonging to multi-time-use files or active program data.
51db7ca2
MD
1481 *
1482 * NOTE: The inactive target is aggressively persued only if the
1483 * inactive queue becomes too small. If the inactive queue
1484 * is large enough to satisfy page movement to free+cache
1485 * then it is repopulated more slowly from the active queue.
e15708fc 1486 * This allows a general inactive_target default to be set.
51db7ca2
MD
1487 *
1488 * There is an issue here for processes which sit mostly idle
1489 * 'overnight', such as sshd, tcsh, and X. Any movement from
1490 * the active queue will eventually cause such pages to
1491 * recycle eventually causing a lot of paging in the morning.
1492 * To reduce the incidence of this pages cycled out of the
1493 * buffer cache are moved directly to the inactive queue if
e15708fc
MD
1494 * they were only used once or twice.
1495 *
1496 * The vfs.vm_cycle_point sysctl can be used to adjust this.
1497 * Increasing the value (up to 64) increases the number of
1498 * buffer recyclements which go directly to the inactive queue.
0e8bd897 1499 */
12e4aaff
MD
1500 if (vmstats.v_free_count > 2048) {
1501 vmstats.v_cache_min = vmstats.v_free_target;
1502 vmstats.v_cache_max = 2 * vmstats.v_cache_min;
984263bc 1503 } else {
12e4aaff
MD
1504 vmstats.v_cache_min = 0;
1505 vmstats.v_cache_max = 0;
984263bc 1506 }
e15708fc 1507 vmstats.v_inactive_target = vmstats.v_free_count / 4;
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MD
1508
1509 /* XXX does not really belong here */
1510 if (vm_page_max_wired == 0)
12e4aaff 1511 vm_page_max_wired = vmstats.v_free_count / 3;
984263bc
MD
1512
1513 if (vm_pageout_stats_max == 0)
12e4aaff 1514 vm_pageout_stats_max = vmstats.v_free_target;
984263bc
MD
1515
1516 /*
1517 * Set interval in seconds for stats scan.
1518 */
1519 if (vm_pageout_stats_interval == 0)
1520 vm_pageout_stats_interval = 5;
1521 if (vm_pageout_full_stats_interval == 0)
1522 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4;
1523
1524
1525 /*
1526 * Set maximum free per pass
1527 */
1528 if (vm_pageout_stats_free_max == 0)
1529 vm_pageout_stats_free_max = 5;
1530
1531 swap_pager_swap_init();
1532 pass = 0;
20479584 1533
984263bc
MD
1534 /*
1535 * The pageout daemon is never done, so loop forever.
1536 */
1537 while (TRUE) {
1538 int error;
984263bc 1539
12d8aca7
MD
1540 /*
1541 * Wait for an action request
1542 */
1543 crit_enter();
20479584 1544 if (vm_pages_needed == 0) {
984263bc 1545 error = tsleep(&vm_pages_needed,
20479584
MD
1546 0, "psleep",
1547 vm_pageout_stats_interval * hz);
1548 if (error && vm_pages_needed == 0) {
984263bc
MD
1549 vm_pageout_page_stats();
1550 continue;
1551 }
20479584 1552 vm_pages_needed = 1;
984263bc 1553 }
12d8aca7 1554 crit_exit();
984263bc 1555
20479584
MD
1556 /*
1557 * If we have enough free memory, wakeup waiters.
12d8aca7 1558 * (This is optional here)
20479584
MD
1559 */
1560 crit_enter();
1561 if (!vm_page_count_min(0))
1562 wakeup(&vmstats.v_free_count);
1563 mycpu->gd_cnt.v_pdwakeups++;
5fd012e0 1564 crit_exit();
20479584
MD
1565
1566 /*
12d8aca7
MD
1567 * Scan for pageout. Try to avoid thrashing the system
1568 * with activity.
20479584 1569 */
12d8aca7 1570 inactive_shortage = vm_pageout_scan(pass);
20479584
MD
1571 if (inactive_shortage > 0) {
1572 ++pass;
1573 if (swap_pager_full) {
1574 /*
1575 * Running out of memory, catastrophic back-off
1576 * to one-second intervals.
1577 */
1578 tsleep(&vm_pages_needed, 0, "pdelay", hz);
1579 } else if (pass < 10 && vm_pages_needed > 1) {
1580 /*
1581 * Normal operation, additional processes
1582 * have already kicked us. Retry immediately.
1583 */
1584 } else if (pass < 10) {
1585 /*
1586 * Normal operation, fewer processes. Delay
1587 * a bit but allow wakeups.
1588 */
1589 vm_pages_needed = 0;
1590 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10);
1591 vm_pages_needed = 1;
1592 } else {
1593 /*
1594 * We've taken too many passes, forced delay.
1595 */
1596 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10);
1597 }
1598 } else {
12d8aca7
MD
1599 /*
1600 * Interlocked wakeup of waiters (non-optional)
1601 */
20479584 1602 pass = 0;
12d8aca7
MD
1603 if (vm_pages_needed && !vm_page_count_min(0)) {
1604 wakeup(&vmstats.v_free_count);
1605 vm_pages_needed = 0;
1606 }
20479584 1607 }
984263bc
MD
1608 }
1609}
1610
20479584
MD
1611/*
1612 * Called after allocating a page out of the cache or free queue
1613 * to possibly wake the pagedaemon up to replentish our supply.
1614 *
1615 * We try to generate some hysteresis by waking the pagedaemon up
1616 * when our free+cache pages go below the severe level. The pagedaemon
1617 * tries to get the count back up to at least the minimum, and through
1618 * to the target level if possible.
1619 *
1620 * If the pagedaemon is already active bump vm_pages_needed as a hint
1621 * that there are even more requests pending.
1622 */
984263bc 1623void
57e43348 1624pagedaemon_wakeup(void)
984263bc 1625{
20479584
MD
1626 if (vm_page_count_severe() && curthread != pagethread) {
1627 if (vm_pages_needed == 0) {
1628 vm_pages_needed = 1;
1629 wakeup(&vm_pages_needed);
1630 } else if (vm_page_count_min(0)) {
1631 ++vm_pages_needed;
1632 }
984263bc
MD
1633 }
1634}
1635
1636#if !defined(NO_SWAPPING)
1637static void
57e43348 1638vm_req_vmdaemon(void)
984263bc
MD
1639{
1640 static int lastrun = 0;
1641
1642 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
1643 wakeup(&vm_daemon_needed);
1644 lastrun = ticks;
1645 }
1646}
1647
8fa76237
MD
1648static int vm_daemon_callback(struct proc *p, void *data __unused);
1649
984263bc 1650static void
57e43348 1651vm_daemon(void)
984263bc 1652{
984263bc 1653 while (TRUE) {
377d4740 1654 tsleep(&vm_daemon_needed, 0, "psleep", 0);
984263bc
MD
1655 if (vm_pageout_req_swapout) {
1656 swapout_procs(vm_pageout_req_swapout);
1657 vm_pageout_req_swapout = 0;
1658 }
1659 /*
1660 * scan the processes for exceeding their rlimits or if
1661 * process is swapped out -- deactivate pages
1662 */
8fa76237
MD
1663 allproc_scan(vm_daemon_callback, NULL);
1664 }
1665}
984263bc 1666
8fa76237
MD
1667static int
1668vm_daemon_callback(struct proc *p, void *data __unused)
1669{
1670 vm_pindex_t limit, size;
984263bc 1671
8fa76237
MD
1672 /*
1673 * if this is a system process or if we have already
1674 * looked at this process, skip it.
1675 */
1676 if (p->p_flag & (P_SYSTEM | P_WEXIT))
1677 return (0);
984263bc 1678
8fa76237
MD
1679 /*
1680 * if the process is in a non-running type state,
1681 * don't touch it.
1682 */
164b8401 1683 if (p->p_stat != SACTIVE && p->p_stat != SSTOP)
8fa76237 1684 return (0);
984263bc 1685
8fa76237
MD
1686 /*
1687 * get a limit
1688 */
1689 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur,
1690 p->p_rlimit[RLIMIT_RSS].rlim_max));
1691
1692 /*
1693 * let processes that are swapped out really be
1694 * swapped out. Set the limit to nothing to get as
1695 * many pages out to swap as possible.
1696 */
1697 if (p->p_flag & P_SWAPPEDOUT)
1698 limit = 0;
1699
1700 size = vmspace_resident_count(p->p_vmspace);
1701 if (limit >= 0 && size >= limit) {
1702 vm_pageout_map_deactivate_pages(
1703 &p->p_vmspace->vm_map, limit);
984263bc 1704 }
8fa76237 1705 return (0);
984263bc 1706}
8fa76237 1707
984263bc 1708#endif