kernel - Address excessive stall in pageout during deadlock avoidance
[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
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
237/*
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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;
fa1ae1e3 699 struct vnode *vpfailed; /* warning, allowed to be stale */
20479584
MD
700 int maxscan, pcount;
701 int recycle_count;
702 int inactive_shortage, active_shortage;
51db7ca2 703 int inactive_original_shortage;
984263bc
MD
704 vm_object_t object;
705 int actcount;
706 int vnodes_skipped = 0;
707 int maxlaunder;
984263bc
MD
708
709 /*
710 * Do whatever cleanup that the pmap code can.
711 */
712 pmap_collect();
713
984263bc 714 /*
20479584
MD
715 * Calculate our target for the number of free+cache pages we
716 * want to get to. This is higher then the number that causes
717 * allocations to stall (severe) in order to provide hysteresis,
718 * and if we don't make it all the way but get to the minimum
719 * we're happy.
984263bc 720 */
20479584 721 inactive_shortage = vm_paging_target() + vm_pageout_deficit;
51db7ca2 722 inactive_original_shortage = inactive_shortage;
20479584 723 vm_pageout_deficit = 0;
984263bc
MD
724
725 /*
726 * Initialize our marker
727 */
728 bzero(&marker, sizeof(marker));
729 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER;
730 marker.queue = PQ_INACTIVE;
731 marker.wire_count = 1;
732
733 /*
734 * Start scanning the inactive queue for pages we can move to the
735 * cache or free. The scan will stop when the target is reached or
736 * we have scanned the entire inactive queue. Note that m->act_count
737 * is not used to form decisions for the inactive queue, only for the
738 * active queue.
739 *
740 * maxlaunder limits the number of dirty pages we flush per scan.
741 * For most systems a smaller value (16 or 32) is more robust under
742 * extreme memory and disk pressure because any unnecessary writes
743 * to disk can result in extreme performance degredation. However,
744 * systems with excessive dirty pages (especially when MAP_NOSYNC is
745 * used) will die horribly with limited laundering. If the pageout
746 * daemon cannot clean enough pages in the first pass, we let it go
747 * all out in succeeding passes.
748 */
749 if ((maxlaunder = vm_max_launder) <= 1)
750 maxlaunder = 1;
751 if (pass)
752 maxlaunder = 10000;
753
06ecca5a 754 /*
5fd012e0
MD
755 * We will generally be in a critical section throughout the
756 * scan, but we can release it temporarily when we are sitting on a
757 * non-busy page without fear. this is required to prevent an
758 * interrupt from unbusying or freeing a page prior to our busy
759 * check, leaving us on the wrong queue or checking the wrong
760 * page.
06ecca5a 761 */
5fd012e0 762 crit_enter();
984263bc 763rescan0:
fa1ae1e3 764 vpfailed = NULL;
12e4aaff 765 maxscan = vmstats.v_inactive_count;
984263bc 766 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl);
20479584 767 m != NULL && maxscan-- > 0 && inactive_shortage > 0;
06ecca5a
MD
768 m = next
769 ) {
12e4aaff 770 mycpu->gd_cnt.v_pdpages++;
984263bc 771
06ecca5a
MD
772 /*
773 * Give interrupts a chance
774 */
5fd012e0
MD
775 crit_exit();
776 crit_enter();
984263bc 777
06ecca5a
MD
778 /*
779 * It's easier for some of the conditions below to just loop
780 * and catch queue changes here rather then check everywhere
781 * else.
782 */
783 if (m->queue != PQ_INACTIVE)
784 goto rescan0;
984263bc
MD
785 next = TAILQ_NEXT(m, pageq);
786
787 /*
788 * skip marker pages
789 */
790 if (m->flags & PG_MARKER)
791 continue;
792
793 /*
794 * A held page may be undergoing I/O, so skip it.
795 */
796 if (m->hold_count) {
984263bc
MD
797 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
798 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
e527fb6b 799 ++vm_swapcache_inactive_heuristic;
984263bc
MD
800 continue;
801 }
06ecca5a 802
984263bc
MD
803 /*
804 * Dont mess with busy pages, keep in the front of the
805 * queue, most likely are being paged out.
806 */
807 if (m->busy || (m->flags & PG_BUSY)) {
984263bc
MD
808 continue;
809 }
810
984263bc 811 if (m->object->ref_count == 0) {
06ecca5a
MD
812 /*
813 * If the object is not being used, we ignore previous
814 * references.
815 */
984263bc
MD
816 vm_page_flag_clear(m, PG_REFERENCED);
817 pmap_clear_reference(m);
818
984263bc 819 } else if (((m->flags & PG_REFERENCED) == 0) &&
06ecca5a
MD
820 (actcount = pmap_ts_referenced(m))) {
821 /*
822 * Otherwise, if the page has been referenced while
823 * in the inactive queue, we bump the "activation
824 * count" upwards, making it less likely that the
825 * page will be added back to the inactive queue
826 * prematurely again. Here we check the page tables
827 * (or emulated bits, if any), given the upper level
828 * VM system not knowing anything about existing
829 * references.
830 */
984263bc
MD
831 vm_page_activate(m);
832 m->act_count += (actcount + ACT_ADVANCE);
833 continue;
834 }
835
836 /*
837 * If the upper level VM system knows about any page
838 * references, we activate the page. We also set the
839 * "activation count" higher than normal so that we will less
840 * likely place pages back onto the inactive queue again.
841 */
842 if ((m->flags & PG_REFERENCED) != 0) {
843 vm_page_flag_clear(m, PG_REFERENCED);
844 actcount = pmap_ts_referenced(m);
845 vm_page_activate(m);
846 m->act_count += (actcount + ACT_ADVANCE + 1);
847 continue;
848 }
849
850 /*
851 * If the upper level VM system doesn't know anything about
852 * the page being dirty, we have to check for it again. As
853 * far as the VM code knows, any partially dirty pages are
854 * fully dirty.
41a01a4d
MD
855 *
856 * Pages marked PG_WRITEABLE may be mapped into the user
857 * address space of a process running on another cpu. A
858 * user process (without holding the MP lock) running on
859 * another cpu may be able to touch the page while we are
17cde63e
MD
860 * trying to remove it. vm_page_cache() will handle this
861 * case for us.
984263bc
MD
862 */
863 if (m->dirty == 0) {
864 vm_page_test_dirty(m);
865 } else {
866 vm_page_dirty(m);
867 }
868
984263bc 869 if (m->valid == 0) {
41a01a4d
MD
870 /*
871 * Invalid pages can be easily freed
872 */
984263bc 873 vm_pageout_page_free(m);
12e4aaff 874 mycpu->gd_cnt.v_dfree++;
20479584 875 --inactive_shortage;
984263bc
MD
876 } else if (m->dirty == 0) {
877 /*
41a01a4d
MD
878 * Clean pages can be placed onto the cache queue.
879 * This effectively frees them.
984263bc
MD
880 */
881 vm_page_cache(m);
20479584 882 --inactive_shortage;
984263bc
MD
883 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) {
884 /*
885 * Dirty pages need to be paged out, but flushing
886 * a page is extremely expensive verses freeing
887 * a clean page. Rather then artificially limiting
888 * the number of pages we can flush, we instead give
889 * dirty pages extra priority on the inactive queue
890 * by forcing them to be cycled through the queue
891 * twice before being flushed, after which the
892 * (now clean) page will cycle through once more
893 * before being freed. This significantly extends
894 * the thrash point for a heavily loaded machine.
895 */
984263bc
MD
896 vm_page_flag_set(m, PG_WINATCFLS);
897 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
898 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
e527fb6b 899 ++vm_swapcache_inactive_heuristic;
984263bc
MD
900 } else if (maxlaunder > 0) {
901 /*
902 * We always want to try to flush some dirty pages if
903 * we encounter them, to keep the system stable.
904 * Normally this number is small, but under extreme
905 * pressure where there are insufficient clean pages
906 * on the inactive queue, we may have to go all out.
907 */
908 int swap_pageouts_ok;
909 struct vnode *vp = NULL;
910
911 object = m->object;
912
913 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) {
914 swap_pageouts_ok = 1;
915 } else {
916 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts);
917 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts &&
20479584 918 vm_page_count_min(0));
984263bc
MD
919
920 }
921
922 /*
923 * We don't bother paging objects that are "dead".
924 * Those objects are in a "rundown" state.
925 */
926 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
984263bc
MD
927 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
928 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
e527fb6b 929 ++vm_swapcache_inactive_heuristic;
984263bc
MD
930 continue;
931 }
932
933 /*
934 * The object is already known NOT to be dead. It
935 * is possible for the vget() to block the whole
936 * pageout daemon, but the new low-memory handling
937 * code should prevent it.
938 *
939 * The previous code skipped locked vnodes and, worse,
940 * reordered pages in the queue. This results in
941 * completely non-deterministic operation because,
942 * quite often, a vm_fault has initiated an I/O and
943 * is holding a locked vnode at just the point where
944 * the pageout daemon is woken up.
945 *
946 * We can't wait forever for the vnode lock, we might
947 * deadlock due to a vn_read() getting stuck in
948 * vm_wait while holding this vnode. We skip the
949 * vnode if we can't get it in a reasonable amount
950 * of time.
fa1ae1e3
MD
951 *
952 * vpfailed is used to (try to) avoid the case where
953 * a large number of pages are associated with a
954 * locked vnode, which could cause the pageout daemon
955 * to stall for an excessive amount of time.
984263bc 956 */
984263bc 957 if (object->type == OBJT_VNODE) {
fa1ae1e3 958 int flags;
984263bc 959
fa1ae1e3
MD
960 vp = object->handle;
961 flags = LK_EXCLUSIVE | LK_NOOBJ;
962 if (vp == vpfailed)
963 flags |= LK_NOWAIT;
964 else
965 flags |= LK_TIMELOCK;
966 if (vget(vp, flags) != 0) {
967 vpfailed = vp;
984263bc
MD
968 ++pageout_lock_miss;
969 if (object->flags & OBJ_MIGHTBEDIRTY)
970 vnodes_skipped++;
971 continue;
972 }
973
974 /*
975 * The page might have been moved to another
976 * queue during potential blocking in vget()
977 * above. The page might have been freed and
978 * reused for another vnode. The object might
979 * have been reused for another vnode.
980 */
981 if (m->queue != PQ_INACTIVE ||
982 m->object != object ||
983 object->handle != vp) {
984 if (object->flags & OBJ_MIGHTBEDIRTY)
985 vnodes_skipped++;
986 vput(vp);
987 continue;
988 }
989
990 /*
991 * The page may have been busied during the
992 * blocking in vput(); We don't move the
993 * page back onto the end of the queue so that
994 * statistics are more correct if we don't.
995 */
996 if (m->busy || (m->flags & PG_BUSY)) {
997 vput(vp);
998 continue;
999 }
1000
1001 /*
1002 * If the page has become held it might
1003 * be undergoing I/O, so skip it
1004 */
1005 if (m->hold_count) {
984263bc
MD
1006 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
1007 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
e527fb6b 1008 ++vm_swapcache_inactive_heuristic;
984263bc
MD
1009 if (object->flags & OBJ_MIGHTBEDIRTY)
1010 vnodes_skipped++;
1011 vput(vp);
1012 continue;
1013 }
1014 }
1015
1016 /*
1017 * If a page is dirty, then it is either being washed
1018 * (but not yet cleaned) or it is still in the
1019 * laundry. If it is still in the laundry, then we
1020 * start the cleaning operation.
1021 *
1022 * This operation may cluster, invalidating the 'next'
1023 * pointer. To prevent an inordinate number of
1024 * restarts we use our marker to remember our place.
1025 *
20479584
MD
1026 * decrement inactive_shortage on success to account
1027 * for the (future) cleaned page. Otherwise we
1028 * could wind up laundering or cleaning too many
1029 * pages.
984263bc 1030 */
984263bc 1031 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq);
984263bc 1032 if (vm_pageout_clean(m) != 0) {
20479584 1033 --inactive_shortage;
984263bc 1034 --maxlaunder;
c84c24da 1035 }
984263bc
MD
1036 next = TAILQ_NEXT(&marker, pageq);
1037 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq);
984263bc
MD
1038 if (vp != NULL)
1039 vput(vp);
1040 }
1041 }
1042
1043 /*
20479584
MD
1044 * We want to move pages from the active queue to the inactive
1045 * queue to get the inactive queue to the inactive target. If
1046 * we still have a page shortage from above we try to directly free
1047 * clean pages instead of moving them.
06ecca5a 1048 *
20479584
MD
1049 * If we do still have a shortage we keep track of the number of
1050 * pages we free or cache (recycle_count) as a measure of thrashing
1051 * between the active and inactive queues.
1052 *
51db7ca2
MD
1053 * If we were able to completely satisfy the free+cache targets
1054 * from the inactive pool we limit the number of pages we move
1055 * from the active pool to the inactive pool to 2x the pages we
e6e9a0c3
MD
1056 * had removed from the inactive pool (with a minimum of 1/5 the
1057 * inactive target). If we were not able to completely satisfy
1058 * the free+cache targets we go for the whole target aggressively.
20479584
MD
1059 *
1060 * NOTE: Both variables can end up negative.
1061 * NOTE: We are still in a critical section.
984263bc 1062 */
20479584 1063 active_shortage = vmstats.v_inactive_target - vmstats.v_inactive_count;
e6e9a0c3
MD
1064 if (inactive_original_shortage < vmstats.v_inactive_target / 10)
1065 inactive_original_shortage = vmstats.v_inactive_target / 10;
51db7ca2
MD
1066 if (inactive_shortage <= 0 &&
1067 active_shortage > inactive_original_shortage * 2) {
1068 active_shortage = inactive_original_shortage * 2;
1069 }
20479584 1070
12e4aaff 1071 pcount = vmstats.v_active_count;
20479584 1072 recycle_count = 0;
984263bc
MD
1073 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1074
20479584
MD
1075 while ((m != NULL) && (pcount-- > 0) &&
1076 (inactive_shortage > 0 || active_shortage > 0)
1077 ) {
06ecca5a
MD
1078 /*
1079 * Give interrupts a chance.
1080 */
5fd012e0
MD
1081 crit_exit();
1082 crit_enter();
984263bc
MD
1083
1084 /*
06ecca5a 1085 * If the page was ripped out from under us, just stop.
984263bc 1086 */
06ecca5a 1087 if (m->queue != PQ_ACTIVE)
984263bc 1088 break;
984263bc 1089 next = TAILQ_NEXT(m, pageq);
06ecca5a 1090
984263bc
MD
1091 /*
1092 * Don't deactivate pages that are busy.
1093 */
1094 if ((m->busy != 0) ||
1095 (m->flags & PG_BUSY) ||
1096 (m->hold_count != 0)) {
984263bc
MD
1097 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1098 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1099 m = next;
1100 continue;
1101 }
1102
1103 /*
1104 * The count for pagedaemon pages is done after checking the
1105 * page for eligibility...
1106 */
12e4aaff 1107 mycpu->gd_cnt.v_pdpages++;
984263bc
MD
1108
1109 /*
20479584
MD
1110 * Check to see "how much" the page has been used and clear
1111 * the tracking access bits. If the object has no references
1112 * don't bother paying the expense.
984263bc
MD
1113 */
1114 actcount = 0;
1115 if (m->object->ref_count != 0) {
20479584
MD
1116 if (m->flags & PG_REFERENCED)
1117 ++actcount;
984263bc
MD
1118 actcount += pmap_ts_referenced(m);
1119 if (actcount) {
1120 m->act_count += ACT_ADVANCE + actcount;
1121 if (m->act_count > ACT_MAX)
1122 m->act_count = ACT_MAX;
1123 }
1124 }
984263bc
MD
1125 vm_page_flag_clear(m, PG_REFERENCED);
1126
1127 /*
20479584 1128 * actcount is only valid if the object ref_count is non-zero.
984263bc 1129 */
20479584 1130 if (actcount && m->object->ref_count != 0) {
984263bc
MD
1131 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1132 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1133 } else {
1134 m->act_count -= min(m->act_count, ACT_DECLINE);
1135 if (vm_pageout_algorithm ||
1136 m->object->ref_count == 0 ||
20479584
MD
1137 m->act_count < pass + 1
1138 ) {
1139 /*
1140 * Deactivate the page. If we had a
1141 * shortage from our inactive scan try to
1142 * free (cache) the page instead.
e6e9a0c3
MD
1143 *
1144 * Don't just blindly cache the page if
1145 * we do not have a shortage from the
1146 * inactive scan, that could lead to
1147 * gigabytes being moved.
20479584
MD
1148 */
1149 --active_shortage;
1150 if (inactive_shortage > 0 ||
1151 m->object->ref_count == 0) {
1152 if (inactive_shortage > 0)
1153 ++recycle_count;
17cde63e 1154 vm_page_busy(m);
984263bc 1155 vm_page_protect(m, VM_PROT_NONE);
17cde63e 1156 vm_page_wakeup(m);
e6e9a0c3
MD
1157 if (m->dirty == 0 &&
1158 inactive_shortage > 0) {
20479584 1159 --inactive_shortage;
984263bc 1160 vm_page_cache(m);
c84c24da 1161 } else {
984263bc 1162 vm_page_deactivate(m);
c84c24da 1163 }
984263bc
MD
1164 } else {
1165 vm_page_deactivate(m);
1166 }
1167 } else {
984263bc
MD
1168 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1169 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1170 }
1171 }
1172 m = next;
1173 }
1174
984263bc
MD
1175 /*
1176 * We try to maintain some *really* free pages, this allows interrupt
1177 * code to be guaranteed space. Since both cache and free queues
1178 * are considered basically 'free', moving pages from cache to free
1179 * does not effect other calculations.
06ecca5a 1180 *
5fd012e0 1181 * NOTE: we are still in a critical section.
c84c24da
MD
1182 *
1183 * Pages moved from PQ_CACHE to totally free are not counted in the
1184 * pages_freed counter.
984263bc 1185 */
12e4aaff 1186 while (vmstats.v_free_count < vmstats.v_free_reserved) {
984263bc
MD
1187 static int cache_rover = 0;
1188 m = vm_page_list_find(PQ_CACHE, cache_rover, FALSE);
20479584 1189 if (m == NULL)
984263bc
MD
1190 break;
1191 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) ||
1192 m->busy ||
1193 m->hold_count ||
1194 m->wire_count) {
1195#ifdef INVARIANTS
086c1d7e 1196 kprintf("Warning: busy page %p found in cache\n", m);
984263bc
MD
1197#endif
1198 vm_page_deactivate(m);
1199 continue;
1200 }
17cde63e
MD
1201 KKASSERT((m->flags & PG_MAPPED) == 0);
1202 KKASSERT(m->dirty == 0);
984263bc
MD
1203 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK;
1204 vm_pageout_page_free(m);
12e4aaff 1205 mycpu->gd_cnt.v_dfree++;
984263bc 1206 }
06ecca5a 1207
5fd012e0 1208 crit_exit();
984263bc
MD
1209
1210#if !defined(NO_SWAPPING)
1211 /*
1212 * Idle process swapout -- run once per second.
1213 */
1214 if (vm_swap_idle_enabled) {
1215 static long lsec;
1216 if (time_second != lsec) {
1217 vm_pageout_req_swapout |= VM_SWAP_IDLE;
1218 vm_req_vmdaemon();
1219 lsec = time_second;
1220 }
1221 }
1222#endif
1223
1224 /*
1225 * If we didn't get enough free pages, and we have skipped a vnode
1226 * in a writeable object, wakeup the sync daemon. And kick swapout
1227 * if we did not get enough free pages.
1228 */
1229 if (vm_paging_target() > 0) {
20479584 1230 if (vnodes_skipped && vm_page_count_min(0))
418ff780 1231 speedup_syncer();
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1232#if !defined(NO_SWAPPING)
1233 if (vm_swap_enabled && vm_page_count_target()) {
1234 vm_req_vmdaemon();
1235 vm_pageout_req_swapout |= VM_SWAP_NORMAL;
1236 }
1237#endif
1238 }
1239
1240 /*
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MD
1241 * Handle catastrophic conditions. Under good conditions we should
1242 * be at the target, well beyond our minimum. If we could not even
1243 * reach our minimum the system is under heavy stress.
1244 *
1245 * Determine whether we have run out of memory. This occurs when
1246 * swap_pager_full is TRUE and the only pages left in the page
1247 * queues are dirty. We will still likely have page shortages.
c84c24da
MD
1248 *
1249 * - swap_pager_full is set if insufficient swap was
1250 * available to satisfy a requested pageout.
1251 *
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MD
1252 * - the inactive queue is bloated (4 x size of active queue),
1253 * meaning it is unable to get rid of dirty pages and.
c84c24da 1254 *
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MD
1255 * - vm_page_count_min() without counting pages recycled from the
1256 * active queue (recycle_count) means we could not recover
1257 * enough pages to meet bare minimum needs. This test only
1258 * works if the inactive queue is bloated.
c84c24da 1259 *
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MD
1260 * - due to a positive inactive_shortage we shifted the remaining
1261 * dirty pages from the active queue to the inactive queue
1262 * trying to find clean ones to free.
984263bc 1263 */
20479584 1264 if (swap_pager_full && vm_page_count_min(recycle_count))
c84c24da 1265 kprintf("Warning: system low on memory+swap!\n");
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MD
1266 if (swap_pager_full && vm_page_count_min(recycle_count) &&
1267 vmstats.v_inactive_count > vmstats.v_active_count * 4 &&
1268 inactive_shortage > 0) {
1269 /*
1270 * Kill something.
1271 */
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1272 info.bigproc = NULL;
1273 info.bigsize = 0;
1274 allproc_scan(vm_pageout_scan_callback, &info);
1275 if (info.bigproc != NULL) {
1276 killproc(info.bigproc, "out of swap space");
1277 info.bigproc->p_nice = PRIO_MIN;
08f2f1bb
SS
1278 info.bigproc->p_usched->resetpriority(
1279 FIRST_LWP_IN_PROC(info.bigproc));
12e4aaff 1280 wakeup(&vmstats.v_free_count);
8fa76237 1281 PRELE(info.bigproc);
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MD
1282 }
1283 }
20479584 1284 return(inactive_shortage);
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1285}
1286
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1287static int
1288vm_pageout_scan_callback(struct proc *p, void *data)
1289{
1290 struct vm_pageout_scan_info *info = data;
1291 vm_offset_t size;
1292
1293 /*
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1294 * Never kill system processes or init. If we have configured swap
1295 * then try to avoid killing low-numbered pids.
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1296 */
1297 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) ||
1298 ((p->p_pid < 48) && (vm_swap_size != 0))) {
1299 return (0);
1300 }
1301
1302 /*
1303 * if the process is in a non-running type state,
1304 * don't touch it.
1305 */
20479584 1306 if (p->p_stat != SACTIVE && p->p_stat != SSTOP)
8fa76237 1307 return (0);
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1308
1309 /*
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1310 * Get the approximate process size. Note that anonymous pages
1311 * with backing swap will be counted twice, but there should not
1312 * be too many such pages due to the stress the VM system is
1313 * under at this point.
8fa76237 1314 */
20479584 1315 size = vmspace_anonymous_count(p->p_vmspace) +
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MD
1316 vmspace_swap_count(p->p_vmspace);
1317
1318 /*
1319 * If the this process is bigger than the biggest one
1320 * remember it.
1321 */
20479584 1322 if (info->bigsize < size) {
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1323 if (info->bigproc)
1324 PRELE(info->bigproc);
1325 PHOLD(p);
1326 info->bigproc = p;
1327 info->bigsize = size;
1328 }
1329 return(0);
1330}
1331
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1332/*
1333 * This routine tries to maintain the pseudo LRU active queue,
1334 * so that during long periods of time where there is no paging,
1335 * that some statistic accumulation still occurs. This code
1336 * helps the situation where paging just starts to occur.
1337 */
1338static void
57e43348 1339vm_pageout_page_stats(void)
984263bc 1340{
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MD
1341 vm_page_t m,next;
1342 int pcount,tpcount; /* Number of pages to check */
1343 static int fullintervalcount = 0;
1344 int page_shortage;
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1345
1346 page_shortage =
12e4aaff
MD
1347 (vmstats.v_inactive_target + vmstats.v_cache_max + vmstats.v_free_min) -
1348 (vmstats.v_free_count + vmstats.v_inactive_count + vmstats.v_cache_count);
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1349
1350 if (page_shortage <= 0)
1351 return;
1352
5fd012e0 1353 crit_enter();
984263bc 1354
12e4aaff 1355 pcount = vmstats.v_active_count;
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MD
1356 fullintervalcount += vm_pageout_stats_interval;
1357 if (fullintervalcount < vm_pageout_full_stats_interval) {
12e4aaff 1358 tpcount = (vm_pageout_stats_max * vmstats.v_active_count) / vmstats.v_page_count;
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1359 if (pcount > tpcount)
1360 pcount = tpcount;
1361 } else {
1362 fullintervalcount = 0;
1363 }
1364
1365 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1366 while ((m != NULL) && (pcount-- > 0)) {
1367 int actcount;
1368
1369 if (m->queue != PQ_ACTIVE) {
1370 break;
1371 }
1372
1373 next = TAILQ_NEXT(m, pageq);
1374 /*
1375 * Don't deactivate pages that are busy.
1376 */
1377 if ((m->busy != 0) ||
1378 (m->flags & PG_BUSY) ||
1379 (m->hold_count != 0)) {
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MD
1380 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1381 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
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MD
1382 m = next;
1383 continue;
1384 }
1385
1386 actcount = 0;
1387 if (m->flags & PG_REFERENCED) {
1388 vm_page_flag_clear(m, PG_REFERENCED);
1389 actcount += 1;
1390 }
1391
1392 actcount += pmap_ts_referenced(m);
1393 if (actcount) {
1394 m->act_count += ACT_ADVANCE + actcount;
1395 if (m->act_count > ACT_MAX)
1396 m->act_count = ACT_MAX;
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1397 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1398 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
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MD
1399 } else {
1400 if (m->act_count == 0) {
1401 /*
1402 * We turn off page access, so that we have
1403 * more accurate RSS stats. We don't do this
1404 * in the normal page deactivation when the
1405 * system is loaded VM wise, because the
1406 * cost of the large number of page protect
1407 * operations would be higher than the value
1408 * of doing the operation.
1409 */
17cde63e 1410 vm_page_busy(m);
984263bc 1411 vm_page_protect(m, VM_PROT_NONE);
17cde63e 1412 vm_page_wakeup(m);
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1413 vm_page_deactivate(m);
1414 } else {
1415 m->act_count -= min(m->act_count, ACT_DECLINE);
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1416 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1417 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1418 }
1419 }
1420
1421 m = next;
1422 }
5fd012e0 1423 crit_exit();
984263bc
MD
1424}
1425
1426static int
57e43348 1427vm_pageout_free_page_calc(vm_size_t count)
984263bc 1428{
12e4aaff 1429 if (count < vmstats.v_page_count)
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MD
1430 return 0;
1431 /*
1432 * free_reserved needs to include enough for the largest swap pager
1433 * structures plus enough for any pv_entry structs when paging.
1434 */
12e4aaff
MD
1435 if (vmstats.v_page_count > 1024)
1436 vmstats.v_free_min = 4 + (vmstats.v_page_count - 1024) / 200;
984263bc 1437 else
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MD
1438 vmstats.v_free_min = 4;
1439 vmstats.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE +
1440 vmstats.v_interrupt_free_min;
1441 vmstats.v_free_reserved = vm_pageout_page_count +
1442 vmstats.v_pageout_free_min + (count / 768) + PQ_L2_SIZE;
1443 vmstats.v_free_severe = vmstats.v_free_min / 2;
1444 vmstats.v_free_min += vmstats.v_free_reserved;
1445 vmstats.v_free_severe += vmstats.v_free_reserved;
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MD
1446 return 1;
1447}
1448
1449
1450/*
20479584 1451 * vm_pageout is the high level pageout daemon.
984263bc
MD
1452 */
1453static void
57e43348 1454vm_pageout(void)
984263bc
MD
1455{
1456 int pass;
20479584 1457 int inactive_shortage;
984263bc
MD
1458
1459 /*
1460 * Initialize some paging parameters.
1461 */
4ecf7cc9 1462 curthread->td_flags |= TDF_SYSTHREAD;
984263bc 1463
12e4aaff
MD
1464 vmstats.v_interrupt_free_min = 2;
1465 if (vmstats.v_page_count < 2000)
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MD
1466 vm_pageout_page_count = 8;
1467
12e4aaff 1468 vm_pageout_free_page_calc(vmstats.v_page_count);
20479584 1469
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MD
1470 /*
1471 * v_free_target and v_cache_min control pageout hysteresis. Note
1472 * that these are more a measure of the VM cache queue hysteresis
1473 * then the VM free queue. Specifically, v_free_target is the
1474 * high water mark (free+cache pages).
1475 *
1476 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the
1477 * low water mark, while v_free_min is the stop. v_cache_min must
1478 * be big enough to handle memory needs while the pageout daemon
1479 * is signalled and run to free more pages.
1480 */
12e4aaff
MD
1481 if (vmstats.v_free_count > 6144)
1482 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved;
984263bc 1483 else
12e4aaff 1484 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved;
984263bc 1485
0e8bd897
MD
1486 /*
1487 * NOTE: With the new buffer cache b_act_count we want the default
1488 * inactive target to be a percentage of available memory.
1489 *
1490 * The inactive target essentially determines the minimum
1491 * number of 'temporary' pages capable of caching one-time-use
1492 * files when the VM system is otherwise full of pages
1493 * belonging to multi-time-use files or active program data.
51db7ca2
MD
1494 *
1495 * NOTE: The inactive target is aggressively persued only if the
1496 * inactive queue becomes too small. If the inactive queue
1497 * is large enough to satisfy page movement to free+cache
1498 * then it is repopulated more slowly from the active queue.
e15708fc 1499 * This allows a general inactive_target default to be set.
51db7ca2
MD
1500 *
1501 * There is an issue here for processes which sit mostly idle
1502 * 'overnight', such as sshd, tcsh, and X. Any movement from
1503 * the active queue will eventually cause such pages to
1504 * recycle eventually causing a lot of paging in the morning.
1505 * To reduce the incidence of this pages cycled out of the
1506 * buffer cache are moved directly to the inactive queue if
e15708fc
MD
1507 * they were only used once or twice.
1508 *
1509 * The vfs.vm_cycle_point sysctl can be used to adjust this.
1510 * Increasing the value (up to 64) increases the number of
1511 * buffer recyclements which go directly to the inactive queue.
0e8bd897 1512 */
12e4aaff
MD
1513 if (vmstats.v_free_count > 2048) {
1514 vmstats.v_cache_min = vmstats.v_free_target;
1515 vmstats.v_cache_max = 2 * vmstats.v_cache_min;
984263bc 1516 } else {
12e4aaff
MD
1517 vmstats.v_cache_min = 0;
1518 vmstats.v_cache_max = 0;
984263bc 1519 }
e15708fc 1520 vmstats.v_inactive_target = vmstats.v_free_count / 4;
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MD
1521
1522 /* XXX does not really belong here */
1523 if (vm_page_max_wired == 0)
12e4aaff 1524 vm_page_max_wired = vmstats.v_free_count / 3;
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MD
1525
1526 if (vm_pageout_stats_max == 0)
12e4aaff 1527 vm_pageout_stats_max = vmstats.v_free_target;
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MD
1528
1529 /*
1530 * Set interval in seconds for stats scan.
1531 */
1532 if (vm_pageout_stats_interval == 0)
1533 vm_pageout_stats_interval = 5;
1534 if (vm_pageout_full_stats_interval == 0)
1535 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4;
1536
1537
1538 /*
1539 * Set maximum free per pass
1540 */
1541 if (vm_pageout_stats_free_max == 0)
1542 vm_pageout_stats_free_max = 5;
1543
1544 swap_pager_swap_init();
1545 pass = 0;
20479584 1546
984263bc
MD
1547 /*
1548 * The pageout daemon is never done, so loop forever.
1549 */
1550 while (TRUE) {
1551 int error;
984263bc 1552
12d8aca7
MD
1553 /*
1554 * Wait for an action request
1555 */
1556 crit_enter();
20479584 1557 if (vm_pages_needed == 0) {
984263bc 1558 error = tsleep(&vm_pages_needed,
20479584
MD
1559 0, "psleep",
1560 vm_pageout_stats_interval * hz);
1561 if (error && vm_pages_needed == 0) {
984263bc
MD
1562 vm_pageout_page_stats();
1563 continue;
1564 }
20479584 1565 vm_pages_needed = 1;
984263bc 1566 }
12d8aca7 1567 crit_exit();
984263bc 1568
20479584
MD
1569 /*
1570 * If we have enough free memory, wakeup waiters.
12d8aca7 1571 * (This is optional here)
20479584
MD
1572 */
1573 crit_enter();
1574 if (!vm_page_count_min(0))
1575 wakeup(&vmstats.v_free_count);
1576 mycpu->gd_cnt.v_pdwakeups++;
5fd012e0 1577 crit_exit();
20479584
MD
1578
1579 /*
12d8aca7
MD
1580 * Scan for pageout. Try to avoid thrashing the system
1581 * with activity.
20479584 1582 */
12d8aca7 1583 inactive_shortage = vm_pageout_scan(pass);
20479584
MD
1584 if (inactive_shortage > 0) {
1585 ++pass;
1586 if (swap_pager_full) {
1587 /*
1588 * Running out of memory, catastrophic back-off
1589 * to one-second intervals.
1590 */
1591 tsleep(&vm_pages_needed, 0, "pdelay", hz);
1592 } else if (pass < 10 && vm_pages_needed > 1) {
1593 /*
1594 * Normal operation, additional processes
1595 * have already kicked us. Retry immediately.
1596 */
1597 } else if (pass < 10) {
1598 /*
1599 * Normal operation, fewer processes. Delay
1600 * a bit but allow wakeups.
1601 */
1602 vm_pages_needed = 0;
1603 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10);
1604 vm_pages_needed = 1;
1605 } else {
1606 /*
1607 * We've taken too many passes, forced delay.
1608 */
1609 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10);
1610 }
1611 } else {
12d8aca7
MD
1612 /*
1613 * Interlocked wakeup of waiters (non-optional)
1614 */
20479584 1615 pass = 0;
12d8aca7
MD
1616 if (vm_pages_needed && !vm_page_count_min(0)) {
1617 wakeup(&vmstats.v_free_count);
1618 vm_pages_needed = 0;
1619 }
20479584 1620 }
984263bc
MD
1621 }
1622}
1623
20479584
MD
1624/*
1625 * Called after allocating a page out of the cache or free queue
1626 * to possibly wake the pagedaemon up to replentish our supply.
1627 *
1628 * We try to generate some hysteresis by waking the pagedaemon up
1629 * when our free+cache pages go below the severe level. The pagedaemon
1630 * tries to get the count back up to at least the minimum, and through
1631 * to the target level if possible.
1632 *
1633 * If the pagedaemon is already active bump vm_pages_needed as a hint
1634 * that there are even more requests pending.
1635 */
984263bc 1636void
57e43348 1637pagedaemon_wakeup(void)
984263bc 1638{
20479584
MD
1639 if (vm_page_count_severe() && curthread != pagethread) {
1640 if (vm_pages_needed == 0) {
1641 vm_pages_needed = 1;
1642 wakeup(&vm_pages_needed);
1643 } else if (vm_page_count_min(0)) {
1644 ++vm_pages_needed;
1645 }
984263bc
MD
1646 }
1647}
1648
1649#if !defined(NO_SWAPPING)
1650static void
57e43348 1651vm_req_vmdaemon(void)
984263bc
MD
1652{
1653 static int lastrun = 0;
1654
1655 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
1656 wakeup(&vm_daemon_needed);
1657 lastrun = ticks;
1658 }
1659}
1660
8fa76237
MD
1661static int vm_daemon_callback(struct proc *p, void *data __unused);
1662
984263bc 1663static void
57e43348 1664vm_daemon(void)
984263bc 1665{
984263bc 1666 while (TRUE) {
377d4740 1667 tsleep(&vm_daemon_needed, 0, "psleep", 0);
984263bc
MD
1668 if (vm_pageout_req_swapout) {
1669 swapout_procs(vm_pageout_req_swapout);
1670 vm_pageout_req_swapout = 0;
1671 }
1672 /*
1673 * scan the processes for exceeding their rlimits or if
1674 * process is swapped out -- deactivate pages
1675 */
8fa76237
MD
1676 allproc_scan(vm_daemon_callback, NULL);
1677 }
1678}
984263bc 1679
8fa76237
MD
1680static int
1681vm_daemon_callback(struct proc *p, void *data __unused)
1682{
1683 vm_pindex_t limit, size;
984263bc 1684
8fa76237
MD
1685 /*
1686 * if this is a system process or if we have already
1687 * looked at this process, skip it.
1688 */
1689 if (p->p_flag & (P_SYSTEM | P_WEXIT))
1690 return (0);
984263bc 1691
8fa76237
MD
1692 /*
1693 * if the process is in a non-running type state,
1694 * don't touch it.
1695 */
164b8401 1696 if (p->p_stat != SACTIVE && p->p_stat != SSTOP)
8fa76237 1697 return (0);
984263bc 1698
8fa76237
MD
1699 /*
1700 * get a limit
1701 */
1702 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur,
1703 p->p_rlimit[RLIMIT_RSS].rlim_max));
1704
1705 /*
1706 * let processes that are swapped out really be
1707 * swapped out. Set the limit to nothing to get as
1708 * many pages out to swap as possible.
1709 */
1710 if (p->p_flag & P_SWAPPEDOUT)
1711 limit = 0;
1712
1713 size = vmspace_resident_count(p->p_vmspace);
1714 if (limit >= 0 && size >= limit) {
1715 vm_pageout_map_deactivate_pages(
1716 &p->p_vmspace->vm_map, limit);
984263bc 1717 }
8fa76237 1718 return (0);
984263bc 1719}
8fa76237 1720
984263bc 1721#endif