Resurrect z*grep script to support gzip'ped files.
[dragonfly.git] / sys / vm / vm_pageout.c
CommitLineData
984263bc 1/*
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2 * (MPSAFE)
3 *
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4 * Copyright (c) 1991 Regents of the University of California.
5 * All rights reserved.
6 * Copyright (c) 1994 John S. Dyson
7 * All rights reserved.
8 * Copyright (c) 1994 David Greenman
9 * All rights reserved.
10 *
11 * This code is derived from software contributed to Berkeley by
12 * The Mach Operating System project at Carnegie-Mellon University.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
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22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91
39 *
40 *
41 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
42 * All rights reserved.
43 *
44 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
45 *
46 * Permission to use, copy, modify and distribute this software and
47 * its documentation is hereby granted, provided that both the copyright
48 * notice and this permission notice appear in all copies of the
49 * software, derivative works or modified versions, and any portions
50 * thereof, and that both notices appear in supporting documentation.
51 *
52 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
53 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
54 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
55 *
56 * Carnegie Mellon requests users of this software to return to
57 *
58 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
59 * School of Computer Science
60 * Carnegie Mellon University
61 * Pittsburgh PA 15213-3890
62 *
63 * any improvements or extensions that they make and grant Carnegie the
64 * rights to redistribute these changes.
65 *
66 * $FreeBSD: src/sys/vm/vm_pageout.c,v 1.151.2.15 2002/12/29 18:21:04 dillon Exp $
67 */
68
69/*
70 * The proverbial page-out daemon.
71 */
72
73#include "opt_vm.h"
74#include <sys/param.h>
75#include <sys/systm.h>
76#include <sys/kernel.h>
77#include <sys/proc.h>
78#include <sys/kthread.h>
79#include <sys/resourcevar.h>
80#include <sys/signalvar.h>
81#include <sys/vnode.h>
82#include <sys/vmmeter.h>
83#include <sys/sysctl.h>
84
85#include <vm/vm.h>
86#include <vm/vm_param.h>
87#include <sys/lock.h>
88#include <vm/vm_object.h>
89#include <vm/vm_page.h>
90#include <vm/vm_map.h>
91#include <vm/vm_pageout.h>
92#include <vm/vm_pager.h>
93#include <vm/swap_pager.h>
94#include <vm/vm_extern.h>
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95
96#include <sys/thread2.h>
12e4aaff 97#include <vm/vm_page2.h>
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98
99/*
100 * System initialization
101 */
102
103/* the kernel process "vm_pageout"*/
1388df65 104static int vm_pageout_clean (vm_page_t);
20479584 105static int vm_pageout_scan (int pass);
1388df65 106static int vm_pageout_free_page_calc (vm_size_t count);
bc6dffab 107struct thread *pagethread;
984263bc 108
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109#if !defined(NO_SWAPPING)
110/* the kernel process "vm_daemon"*/
1388df65 111static void vm_daemon (void);
bc6dffab 112static struct thread *vmthread;
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113
114static struct kproc_desc vm_kp = {
115 "vmdaemon",
116 vm_daemon,
bc6dffab 117 &vmthread
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118};
119SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp)
120#endif
121
122
123int vm_pages_needed=0; /* Event on which pageout daemon sleeps */
124int vm_pageout_deficit=0; /* Estimated number of pages deficit */
125int vm_pageout_pages_needed=0; /* flag saying that the pageout daemon needs pages */
126
127#if !defined(NO_SWAPPING)
128static int vm_pageout_req_swapout; /* XXX */
129static int vm_daemon_needed;
130#endif
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131static int vm_max_launder = 32;
132static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0;
133static int vm_pageout_full_stats_interval = 0;
134static int vm_pageout_stats_free_max=0, vm_pageout_algorithm=0;
135static int defer_swap_pageouts=0;
136static int disable_swap_pageouts=0;
137
138#if defined(NO_SWAPPING)
139static int vm_swap_enabled=0;
140static int vm_swap_idle_enabled=0;
141#else
142static int vm_swap_enabled=1;
143static int vm_swap_idle_enabled=0;
144#endif
145
146SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm,
147 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt");
148
149SYSCTL_INT(_vm, OID_AUTO, max_launder,
150 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout");
151
152SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max,
153 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length");
154
155SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval,
156 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan");
157
158SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval,
159 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan");
160
161SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max,
162 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented");
163
164#if defined(NO_SWAPPING)
165SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
166 CTLFLAG_RD, &vm_swap_enabled, 0, "");
167SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
168 CTLFLAG_RD, &vm_swap_idle_enabled, 0, "");
169#else
170SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled,
171 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout");
172SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled,
173 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria");
174#endif
175
176SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts,
177 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem");
178
179SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts,
180 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages");
181
182static int pageout_lock_miss;
183SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss,
184 CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout");
185
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186int vm_load;
187SYSCTL_INT(_vm, OID_AUTO, vm_load,
188 CTLFLAG_RD, &vm_load, 0, "load on the VM system");
189int vm_load_enable = 1;
190SYSCTL_INT(_vm, OID_AUTO, vm_load_enable,
191 CTLFLAG_RW, &vm_load_enable, 0, "enable vm_load rate limiting");
192#ifdef INVARIANTS
193int vm_load_debug;
194SYSCTL_INT(_vm, OID_AUTO, vm_load_debug,
195 CTLFLAG_RW, &vm_load_debug, 0, "debug vm_load");
196#endif
197
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198#define VM_PAGEOUT_PAGE_COUNT 16
199int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT;
200
201int vm_page_max_wired; /* XXX max # of wired pages system-wide */
202
203#if !defined(NO_SWAPPING)
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204typedef void freeer_fcn_t (vm_map_t, vm_object_t, vm_pindex_t, int);
205static void vm_pageout_map_deactivate_pages (vm_map_t, vm_pindex_t);
984263bc 206static freeer_fcn_t vm_pageout_object_deactivate_pages;
1388df65 207static void vm_req_vmdaemon (void);
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208#endif
209static void vm_pageout_page_stats(void);
210
46311ac2 211/*
20479584 212 * Update vm_load to slow down faulting processes.
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213 *
214 * SMP races ok.
215 * No requirements.
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216 */
217void
218vm_fault_ratecheck(void)
219{
220 if (vm_pages_needed) {
221 if (vm_load < 1000)
222 ++vm_load;
223 } else {
224 if (vm_load > 0)
225 --vm_load;
226 }
227}
228
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229/*
230 * vm_pageout_clean:
231 *
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232 * Clean the page and remove it from the laundry. The page must not be
233 * busy on-call.
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234 *
235 * We set the busy bit to cause potential page faults on this page to
236 * block. Note the careful timing, however, the busy bit isn't set till
237 * late and we cannot do anything that will mess with the page.
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238 *
239 * The caller must hold vm_token.
984263bc 240 */
984263bc 241static int
57e43348 242vm_pageout_clean(vm_page_t m)
984263bc 243{
5f910b2f 244 vm_object_t object;
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245 vm_page_t mc[2*vm_pageout_page_count];
246 int pageout_count;
247 int ib, is, page_base;
248 vm_pindex_t pindex = m->pindex;
249
250 object = m->object;
251
252 /*
253 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP
254 * with the new swapper, but we could have serious problems paging
255 * out other object types if there is insufficient memory.
256 *
257 * Unfortunately, checking free memory here is far too late, so the
258 * check has been moved up a procedural level.
259 */
260
261 /*
262 * Don't mess with the page if it's busy, held, or special
263 */
264 if ((m->hold_count != 0) ||
265 ((m->busy != 0) || (m->flags & (PG_BUSY|PG_UNMANAGED)))) {
266 return 0;
267 }
268
269 mc[vm_pageout_page_count] = m;
270 pageout_count = 1;
271 page_base = vm_pageout_page_count;
272 ib = 1;
273 is = 1;
274
275 /*
276 * Scan object for clusterable pages.
277 *
278 * We can cluster ONLY if: ->> the page is NOT
279 * clean, wired, busy, held, or mapped into a
280 * buffer, and one of the following:
281 * 1) The page is inactive, or a seldom used
282 * active page.
283 * -or-
284 * 2) we force the issue.
285 *
286 * During heavy mmap/modification loads the pageout
287 * daemon can really fragment the underlying file
288 * due to flushing pages out of order and not trying
289 * align the clusters (which leave sporatic out-of-order
290 * holes). To solve this problem we do the reverse scan
291 * first and attempt to align our cluster, then do a
292 * forward scan if room remains.
293 */
294
398c240d 295 vm_object_hold(object);
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296more:
297 while (ib && pageout_count < vm_pageout_page_count) {
298 vm_page_t p;
299
300 if (ib > pindex) {
301 ib = 0;
302 break;
303 }
304
305 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) {
306 ib = 0;
307 break;
308 }
309 if (((p->queue - p->pc) == PQ_CACHE) ||
310 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) {
311 ib = 0;
312 break;
313 }
314 vm_page_test_dirty(p);
315 if ((p->dirty & p->valid) == 0 ||
316 p->queue != PQ_INACTIVE ||
317 p->wire_count != 0 || /* may be held by buf cache */
318 p->hold_count != 0) { /* may be undergoing I/O */
319 ib = 0;
320 break;
321 }
322 mc[--page_base] = p;
323 ++pageout_count;
324 ++ib;
325 /*
326 * alignment boundry, stop here and switch directions. Do
327 * not clear ib.
328 */
329 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0)
330 break;
331 }
332
333 while (pageout_count < vm_pageout_page_count &&
334 pindex + is < object->size) {
335 vm_page_t p;
336
337 if ((p = vm_page_lookup(object, pindex + is)) == NULL)
338 break;
339 if (((p->queue - p->pc) == PQ_CACHE) ||
340 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) {
341 break;
342 }
343 vm_page_test_dirty(p);
344 if ((p->dirty & p->valid) == 0 ||
345 p->queue != PQ_INACTIVE ||
346 p->wire_count != 0 || /* may be held by buf cache */
347 p->hold_count != 0) { /* may be undergoing I/O */
348 break;
349 }
350 mc[page_base + pageout_count] = p;
351 ++pageout_count;
352 ++is;
353 }
354
355 /*
356 * If we exhausted our forward scan, continue with the reverse scan
357 * when possible, even past a page boundry. This catches boundry
358 * conditions.
359 */
360 if (ib && pageout_count < vm_pageout_page_count)
361 goto more;
362
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363 vm_object_drop(object);
364
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365 /*
366 * we allow reads during pageouts...
367 */
368 return vm_pageout_flush(&mc[page_base], pageout_count, 0);
369}
370
371/*
372 * vm_pageout_flush() - launder the given pages
373 *
374 * The given pages are laundered. Note that we setup for the start of
375 * I/O ( i.e. busy the page ), mark it read-only, and bump the object
376 * reference count all in here rather then in the parent. If we want
377 * the parent to do more sophisticated things we may have to change
378 * the ordering.
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379 *
380 * The caller must hold vm_token.
984263bc 381 */
984263bc 382int
57e43348 383vm_pageout_flush(vm_page_t *mc, int count, int flags)
984263bc 384{
5f910b2f 385 vm_object_t object;
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386 int pageout_status[count];
387 int numpagedout = 0;
388 int i;
389
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390 ASSERT_LWKT_TOKEN_HELD(&vm_token);
391
984263bc 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.
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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) {
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466 if (vm_page_count_severe())
467 vm_page_deactivate(mt);
468#if 0
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469 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt))
470 vm_page_protect(mt, VM_PROT_READ);
93afe6be 471#endif
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472 vm_page_io_finish(mt);
473 vm_object_pip_wakeup(object);
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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 *
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488 * The map must be locked.
489 * The caller must hold vm_token.
398c240d 490 * The caller must hold the vm_object.
984263bc 491 */
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492static int vm_pageout_object_deactivate_pages_callback(vm_page_t, void *);
493
984263bc 494static void
57e43348 495vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object,
99ad9bc4 496 vm_pindex_t desired, int map_remove_only)
984263bc 497{
1f804340 498 struct rb_vm_page_scan_info info;
398c240d 499 vm_object_t tmp;
984263bc 500 int remove_mode;
984263bc 501
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502 while (object) {
503 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
504 return;
398c240d
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505
506 vm_object_hold(object);
507
508 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS) {
509 vm_object_drop(object);
510 return;
511 }
512 if (object->paging_in_progress) {
513 vm_object_drop(object);
984263bc 514 return;
398c240d 515 }
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516
517 remove_mode = map_remove_only;
518 if (object->shadow_count > 1)
519 remove_mode = 1;
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520
521 /*
522 * scan the objects entire memory queue. spl protection is
523 * required to avoid an interrupt unbusy/free race against
524 * our busy check.
525 */
5fd012e0 526 crit_enter();
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527 info.limit = remove_mode;
528 info.map = map;
529 info.desired = desired;
530 vm_page_rb_tree_RB_SCAN(&object->rb_memq, NULL,
531 vm_pageout_object_deactivate_pages_callback,
532 &info
533 );
534 crit_exit();
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535 tmp = object->backing_object;
536 vm_object_drop(object);
537 object = tmp;
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538 }
539}
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540
541/*
542 * The caller must hold vm_token.
398c240d 543 * The caller must hold the vm_object.
99ad9bc4 544 */
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545static int
546vm_pageout_object_deactivate_pages_callback(vm_page_t p, void *data)
547{
548 struct rb_vm_page_scan_info *info = data;
549 int actcount;
984263bc 550
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551 if (pmap_resident_count(vm_map_pmap(info->map)) <= info->desired) {
552 return(-1);
553 }
554 mycpu->gd_cnt.v_pdpages++;
555 if (p->wire_count != 0 || p->hold_count != 0 || p->busy != 0 ||
556 (p->flags & (PG_BUSY|PG_UNMANAGED)) ||
557 !pmap_page_exists_quick(vm_map_pmap(info->map), p)) {
558 return(0);
559 }
984263bc 560
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561 actcount = pmap_ts_referenced(p);
562 if (actcount) {
563 vm_page_flag_set(p, PG_REFERENCED);
564 } else if (p->flags & PG_REFERENCED) {
565 actcount = 1;
566 }
567
568 if ((p->queue != PQ_ACTIVE) &&
569 (p->flags & PG_REFERENCED)) {
570 vm_page_activate(p);
571 p->act_count += actcount;
572 vm_page_flag_clear(p, PG_REFERENCED);
573 } else if (p->queue == PQ_ACTIVE) {
574 if ((p->flags & PG_REFERENCED) == 0) {
575 p->act_count -= min(p->act_count, ACT_DECLINE);
576 if (!info->limit && (vm_pageout_algorithm || (p->act_count == 0))) {
17cde63e 577 vm_page_busy(p);
984263bc 578 vm_page_protect(p, VM_PROT_NONE);
1f804340 579 vm_page_deactivate(p);
a491077e 580 vm_page_wakeup(p);
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581 } else {
582 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq);
583 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq);
984263bc 584 }
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585 } else {
586 vm_page_activate(p);
587 vm_page_flag_clear(p, PG_REFERENCED);
588 if (p->act_count < (ACT_MAX - ACT_ADVANCE))
589 p->act_count += ACT_ADVANCE;
590 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, p, pageq);
591 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, p, pageq);
984263bc 592 }
1f804340 593 } else if (p->queue == PQ_INACTIVE) {
17cde63e 594 vm_page_busy(p);
1f804340 595 vm_page_protect(p, VM_PROT_NONE);
17cde63e 596 vm_page_wakeup(p);
984263bc 597 }
1f804340 598 return(0);
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599}
600
601/*
99ad9bc4 602 * Deactivate some number of pages in a map, try to do it fairly, but
984263bc 603 * that is really hard to do.
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604 *
605 * The caller must hold vm_token.
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606 */
607static void
57e43348 608vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired)
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609{
610 vm_map_entry_t tmpe;
611 vm_object_t obj, bigobj;
612 int nothingwired;
613
df4f70a6 614 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT)) {
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615 return;
616 }
617
618 bigobj = NULL;
619 nothingwired = TRUE;
620
621 /*
622 * first, search out the biggest object, and try to free pages from
623 * that.
624 */
625 tmpe = map->header.next;
626 while (tmpe != &map->header) {
1b874851
MD
627 switch(tmpe->maptype) {
628 case VM_MAPTYPE_NORMAL:
629 case VM_MAPTYPE_VPAGETABLE:
984263bc
MD
630 obj = tmpe->object.vm_object;
631 if ((obj != NULL) && (obj->shadow_count <= 1) &&
632 ((bigobj == NULL) ||
633 (bigobj->resident_page_count < obj->resident_page_count))) {
634 bigobj = obj;
635 }
1b874851
MD
636 break;
637 default:
638 break;
984263bc
MD
639 }
640 if (tmpe->wired_count > 0)
641 nothingwired = FALSE;
642 tmpe = tmpe->next;
643 }
644
398c240d 645 if (bigobj)
984263bc
MD
646 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0);
647
648 /*
649 * Next, hunt around for other pages to deactivate. We actually
650 * do this search sort of wrong -- .text first is not the best idea.
651 */
652 tmpe = map->header.next;
653 while (tmpe != &map->header) {
654 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
655 break;
1b874851
MD
656 switch(tmpe->maptype) {
657 case VM_MAPTYPE_NORMAL:
658 case VM_MAPTYPE_VPAGETABLE:
984263bc 659 obj = tmpe->object.vm_object;
398c240d 660 if (obj)
984263bc 661 vm_pageout_object_deactivate_pages(map, obj, desired, 0);
1b874851
MD
662 break;
663 default:
664 break;
984263bc
MD
665 }
666 tmpe = tmpe->next;
667 };
668
669 /*
670 * Remove all mappings if a process is swapped out, this will free page
671 * table pages.
672 */
673 if (desired == 0 && nothingwired)
674 pmap_remove(vm_map_pmap(map),
88181b08 675 VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS);
984263bc 676 vm_map_unlock(map);
984263bc
MD
677}
678#endif
679
680/*
a11aaa81
MD
681 * Don't try to be fancy - being fancy can lead to vnode deadlocks. We
682 * only do it for OBJT_DEFAULT and OBJT_SWAP objects which we know can
683 * be trivially freed.
99ad9bc4
MD
684 *
685 * The caller must hold vm_token.
a491077e
MD
686 *
687 * WARNING: vm_object_reference() can block.
984263bc 688 */
99ad9bc4 689static void
95813af0
MD
690vm_pageout_page_free(vm_page_t m)
691{
984263bc
MD
692 vm_object_t object = m->object;
693 int type = object->type;
694
a491077e 695 vm_page_busy(m);
984263bc
MD
696 if (type == OBJT_SWAP || type == OBJT_DEFAULT)
697 vm_object_reference(object);
984263bc
MD
698 vm_page_protect(m, VM_PROT_NONE);
699 vm_page_free(m);
700 if (type == OBJT_SWAP || type == OBJT_DEFAULT)
701 vm_object_deallocate(object);
702}
703
704/*
20479584 705 * vm_pageout_scan does the dirty work for the pageout daemon.
984263bc 706 */
8fa76237
MD
707struct vm_pageout_scan_info {
708 struct proc *bigproc;
709 vm_offset_t bigsize;
710};
711
712static int vm_pageout_scan_callback(struct proc *p, void *data);
713
99ad9bc4
MD
714/*
715 * The caller must hold vm_token.
716 */
20479584 717static int
984263bc
MD
718vm_pageout_scan(int pass)
719{
8fa76237 720 struct vm_pageout_scan_info info;
984263bc
MD
721 vm_page_t m, next;
722 struct vm_page marker;
5d6a945b 723 struct vnode *vpfailed; /* warning, allowed to be stale */
20479584
MD
724 int maxscan, pcount;
725 int recycle_count;
726 int inactive_shortage, active_shortage;
51db7ca2 727 int inactive_original_shortage;
984263bc
MD
728 vm_object_t object;
729 int actcount;
730 int vnodes_skipped = 0;
731 int maxlaunder;
984263bc
MD
732
733 /*
734 * Do whatever cleanup that the pmap code can.
735 */
736 pmap_collect();
737
984263bc 738 /*
20479584
MD
739 * Calculate our target for the number of free+cache pages we
740 * want to get to. This is higher then the number that causes
741 * allocations to stall (severe) in order to provide hysteresis,
742 * and if we don't make it all the way but get to the minimum
743 * we're happy.
984263bc 744 */
20479584 745 inactive_shortage = vm_paging_target() + vm_pageout_deficit;
51db7ca2 746 inactive_original_shortage = inactive_shortage;
20479584 747 vm_pageout_deficit = 0;
984263bc
MD
748
749 /*
750 * Initialize our marker
751 */
752 bzero(&marker, sizeof(marker));
753 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER;
754 marker.queue = PQ_INACTIVE;
755 marker.wire_count = 1;
756
757 /*
758 * Start scanning the inactive queue for pages we can move to the
759 * cache or free. The scan will stop when the target is reached or
760 * we have scanned the entire inactive queue. Note that m->act_count
761 * is not used to form decisions for the inactive queue, only for the
762 * active queue.
763 *
764 * maxlaunder limits the number of dirty pages we flush per scan.
765 * For most systems a smaller value (16 or 32) is more robust under
766 * extreme memory and disk pressure because any unnecessary writes
767 * to disk can result in extreme performance degredation. However,
768 * systems with excessive dirty pages (especially when MAP_NOSYNC is
769 * used) will die horribly with limited laundering. If the pageout
770 * daemon cannot clean enough pages in the first pass, we let it go
771 * all out in succeeding passes.
772 */
773 if ((maxlaunder = vm_max_launder) <= 1)
774 maxlaunder = 1;
775 if (pass)
776 maxlaunder = 10000;
777
06ecca5a 778 /*
5fd012e0
MD
779 * We will generally be in a critical section throughout the
780 * scan, but we can release it temporarily when we are sitting on a
781 * non-busy page without fear. this is required to prevent an
782 * interrupt from unbusying or freeing a page prior to our busy
783 * check, leaving us on the wrong queue or checking the wrong
784 * page.
06ecca5a 785 */
5fd012e0 786 crit_enter();
984263bc 787rescan0:
5d6a945b 788 vpfailed = NULL;
12e4aaff 789 maxscan = vmstats.v_inactive_count;
984263bc 790 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl);
20479584 791 m != NULL && maxscan-- > 0 && inactive_shortage > 0;
06ecca5a
MD
792 m = next
793 ) {
12e4aaff 794 mycpu->gd_cnt.v_pdpages++;
984263bc 795
06ecca5a
MD
796 /*
797 * Give interrupts a chance
798 */
5fd012e0
MD
799 crit_exit();
800 crit_enter();
984263bc 801
06ecca5a
MD
802 /*
803 * It's easier for some of the conditions below to just loop
804 * and catch queue changes here rather then check everywhere
805 * else.
806 */
807 if (m->queue != PQ_INACTIVE)
808 goto rescan0;
984263bc
MD
809 next = TAILQ_NEXT(m, pageq);
810
811 /*
812 * skip marker pages
813 */
814 if (m->flags & PG_MARKER)
815 continue;
816
817 /*
818 * A held page may be undergoing I/O, so skip it.
819 */
820 if (m->hold_count) {
984263bc
MD
821 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
822 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
e527fb6b 823 ++vm_swapcache_inactive_heuristic;
984263bc
MD
824 continue;
825 }
06ecca5a 826
984263bc
MD
827 /*
828 * Dont mess with busy pages, keep in the front of the
829 * queue, most likely are being paged out.
830 */
831 if (m->busy || (m->flags & PG_BUSY)) {
984263bc
MD
832 continue;
833 }
834
984263bc 835 if (m->object->ref_count == 0) {
06ecca5a
MD
836 /*
837 * If the object is not being used, we ignore previous
838 * references.
839 */
984263bc
MD
840 vm_page_flag_clear(m, PG_REFERENCED);
841 pmap_clear_reference(m);
842
984263bc 843 } else if (((m->flags & PG_REFERENCED) == 0) &&
06ecca5a
MD
844 (actcount = pmap_ts_referenced(m))) {
845 /*
846 * Otherwise, if the page has been referenced while
847 * in the inactive queue, we bump the "activation
848 * count" upwards, making it less likely that the
849 * page will be added back to the inactive queue
850 * prematurely again. Here we check the page tables
851 * (or emulated bits, if any), given the upper level
852 * VM system not knowing anything about existing
853 * references.
854 */
984263bc
MD
855 vm_page_activate(m);
856 m->act_count += (actcount + ACT_ADVANCE);
857 continue;
858 }
859
860 /*
861 * If the upper level VM system knows about any page
862 * references, we activate the page. We also set the
863 * "activation count" higher than normal so that we will less
864 * likely place pages back onto the inactive queue again.
865 */
866 if ((m->flags & PG_REFERENCED) != 0) {
867 vm_page_flag_clear(m, PG_REFERENCED);
868 actcount = pmap_ts_referenced(m);
869 vm_page_activate(m);
870 m->act_count += (actcount + ACT_ADVANCE + 1);
871 continue;
872 }
873
874 /*
875 * If the upper level VM system doesn't know anything about
876 * the page being dirty, we have to check for it again. As
877 * far as the VM code knows, any partially dirty pages are
878 * fully dirty.
41a01a4d
MD
879 *
880 * Pages marked PG_WRITEABLE may be mapped into the user
881 * address space of a process running on another cpu. A
882 * user process (without holding the MP lock) running on
883 * another cpu may be able to touch the page while we are
17cde63e
MD
884 * trying to remove it. vm_page_cache() will handle this
885 * case for us.
984263bc
MD
886 */
887 if (m->dirty == 0) {
888 vm_page_test_dirty(m);
889 } else {
890 vm_page_dirty(m);
891 }
892
984263bc 893 if (m->valid == 0) {
41a01a4d
MD
894 /*
895 * Invalid pages can be easily freed
896 */
984263bc 897 vm_pageout_page_free(m);
12e4aaff 898 mycpu->gd_cnt.v_dfree++;
20479584 899 --inactive_shortage;
984263bc
MD
900 } else if (m->dirty == 0) {
901 /*
41a01a4d
MD
902 * Clean pages can be placed onto the cache queue.
903 * This effectively frees them.
984263bc 904 */
a491077e 905 vm_page_busy(m);
984263bc 906 vm_page_cache(m);
20479584 907 --inactive_shortage;
984263bc
MD
908 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) {
909 /*
910 * Dirty pages need to be paged out, but flushing
911 * a page is extremely expensive verses freeing
912 * a clean page. Rather then artificially limiting
913 * the number of pages we can flush, we instead give
914 * dirty pages extra priority on the inactive queue
915 * by forcing them to be cycled through the queue
916 * twice before being flushed, after which the
917 * (now clean) page will cycle through once more
918 * before being freed. This significantly extends
919 * the thrash point for a heavily loaded machine.
920 */
984263bc
MD
921 vm_page_flag_set(m, PG_WINATCFLS);
922 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
923 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
e527fb6b 924 ++vm_swapcache_inactive_heuristic;
984263bc
MD
925 } else if (maxlaunder > 0) {
926 /*
927 * We always want to try to flush some dirty pages if
928 * we encounter them, to keep the system stable.
929 * Normally this number is small, but under extreme
930 * pressure where there are insufficient clean pages
931 * on the inactive queue, we may have to go all out.
932 */
933 int swap_pageouts_ok;
934 struct vnode *vp = NULL;
935
936 object = m->object;
937
938 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) {
939 swap_pageouts_ok = 1;
940 } else {
941 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts);
942 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts &&
20479584 943 vm_page_count_min(0));
984263bc
MD
944
945 }
946
947 /*
948 * We don't bother paging objects that are "dead".
949 * Those objects are in a "rundown" state.
950 */
951 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
984263bc
MD
952 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
953 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
e527fb6b 954 ++vm_swapcache_inactive_heuristic;
984263bc
MD
955 continue;
956 }
957
958 /*
959 * The object is already known NOT to be dead. It
960 * is possible for the vget() to block the whole
961 * pageout daemon, but the new low-memory handling
962 * code should prevent it.
963 *
964 * The previous code skipped locked vnodes and, worse,
965 * reordered pages in the queue. This results in
966 * completely non-deterministic operation because,
967 * quite often, a vm_fault has initiated an I/O and
968 * is holding a locked vnode at just the point where
969 * the pageout daemon is woken up.
970 *
971 * We can't wait forever for the vnode lock, we might
972 * deadlock due to a vn_read() getting stuck in
973 * vm_wait while holding this vnode. We skip the
974 * vnode if we can't get it in a reasonable amount
975 * of time.
5d6a945b
MD
976 *
977 * vpfailed is used to (try to) avoid the case where
978 * a large number of pages are associated with a
979 * locked vnode, which could cause the pageout daemon
980 * to stall for an excessive amount of time.
984263bc 981 */
984263bc 982 if (object->type == OBJT_VNODE) {
5d6a945b 983 int flags;
984263bc 984
5d6a945b
MD
985 vp = object->handle;
986 flags = LK_EXCLUSIVE | LK_NOOBJ;
987 if (vp == vpfailed)
988 flags |= LK_NOWAIT;
989 else
990 flags |= LK_TIMELOCK;
991 if (vget(vp, flags) != 0) {
992 vpfailed = vp;
984263bc
MD
993 ++pageout_lock_miss;
994 if (object->flags & OBJ_MIGHTBEDIRTY)
995 vnodes_skipped++;
996 continue;
997 }
998
999 /*
1000 * The page might have been moved to another
1001 * queue during potential blocking in vget()
1002 * above. The page might have been freed and
1003 * reused for another vnode. The object might
1004 * have been reused for another vnode.
1005 */
1006 if (m->queue != PQ_INACTIVE ||
1007 m->object != object ||
1008 object->handle != vp) {
1009 if (object->flags & OBJ_MIGHTBEDIRTY)
1010 vnodes_skipped++;
1011 vput(vp);
1012 continue;
1013 }
1014
1015 /*
1016 * The page may have been busied during the
1017 * blocking in vput(); We don't move the
1018 * page back onto the end of the queue so that
1019 * statistics are more correct if we don't.
1020 */
1021 if (m->busy || (m->flags & PG_BUSY)) {
1022 vput(vp);
1023 continue;
1024 }
1025
1026 /*
1027 * If the page has become held it might
1028 * be undergoing I/O, so skip it
1029 */
1030 if (m->hold_count) {
984263bc
MD
1031 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
1032 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE].pl, m, pageq);
e527fb6b 1033 ++vm_swapcache_inactive_heuristic;
984263bc
MD
1034 if (object->flags & OBJ_MIGHTBEDIRTY)
1035 vnodes_skipped++;
1036 vput(vp);
1037 continue;
1038 }
1039 }
1040
1041 /*
1042 * If a page is dirty, then it is either being washed
1043 * (but not yet cleaned) or it is still in the
1044 * laundry. If it is still in the laundry, then we
1045 * start the cleaning operation.
1046 *
1047 * This operation may cluster, invalidating the 'next'
1048 * pointer. To prevent an inordinate number of
1049 * restarts we use our marker to remember our place.
1050 *
20479584
MD
1051 * decrement inactive_shortage on success to account
1052 * for the (future) cleaned page. Otherwise we
1053 * could wind up laundering or cleaning too many
1054 * pages.
984263bc 1055 */
984263bc 1056 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq);
984263bc 1057 if (vm_pageout_clean(m) != 0) {
20479584 1058 --inactive_shortage;
984263bc 1059 --maxlaunder;
c84c24da 1060 }
984263bc
MD
1061 next = TAILQ_NEXT(&marker, pageq);
1062 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq);
984263bc
MD
1063 if (vp != NULL)
1064 vput(vp);
1065 }
1066 }
1067
1068 /*
20479584
MD
1069 * We want to move pages from the active queue to the inactive
1070 * queue to get the inactive queue to the inactive target. If
1071 * we still have a page shortage from above we try to directly free
1072 * clean pages instead of moving them.
06ecca5a 1073 *
20479584
MD
1074 * If we do still have a shortage we keep track of the number of
1075 * pages we free or cache (recycle_count) as a measure of thrashing
1076 * between the active and inactive queues.
1077 *
51db7ca2
MD
1078 * If we were able to completely satisfy the free+cache targets
1079 * from the inactive pool we limit the number of pages we move
1080 * from the active pool to the inactive pool to 2x the pages we
e6e9a0c3
MD
1081 * had removed from the inactive pool (with a minimum of 1/5 the
1082 * inactive target). If we were not able to completely satisfy
1083 * the free+cache targets we go for the whole target aggressively.
20479584
MD
1084 *
1085 * NOTE: Both variables can end up negative.
1086 * NOTE: We are still in a critical section.
984263bc 1087 */
20479584 1088 active_shortage = vmstats.v_inactive_target - vmstats.v_inactive_count;
e6e9a0c3
MD
1089 if (inactive_original_shortage < vmstats.v_inactive_target / 10)
1090 inactive_original_shortage = vmstats.v_inactive_target / 10;
51db7ca2
MD
1091 if (inactive_shortage <= 0 &&
1092 active_shortage > inactive_original_shortage * 2) {
1093 active_shortage = inactive_original_shortage * 2;
1094 }
20479584 1095
12e4aaff 1096 pcount = vmstats.v_active_count;
20479584 1097 recycle_count = 0;
984263bc
MD
1098 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1099
20479584
MD
1100 while ((m != NULL) && (pcount-- > 0) &&
1101 (inactive_shortage > 0 || active_shortage > 0)
1102 ) {
06ecca5a
MD
1103 /*
1104 * Give interrupts a chance.
1105 */
5fd012e0
MD
1106 crit_exit();
1107 crit_enter();
984263bc
MD
1108
1109 /*
06ecca5a 1110 * If the page was ripped out from under us, just stop.
984263bc 1111 */
06ecca5a 1112 if (m->queue != PQ_ACTIVE)
984263bc 1113 break;
984263bc 1114 next = TAILQ_NEXT(m, pageq);
06ecca5a 1115
984263bc
MD
1116 /*
1117 * Don't deactivate pages that are busy.
1118 */
1119 if ((m->busy != 0) ||
1120 (m->flags & PG_BUSY) ||
1121 (m->hold_count != 0)) {
984263bc
MD
1122 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1123 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1124 m = next;
1125 continue;
1126 }
1127
1128 /*
1129 * The count for pagedaemon pages is done after checking the
1130 * page for eligibility...
1131 */
12e4aaff 1132 mycpu->gd_cnt.v_pdpages++;
984263bc
MD
1133
1134 /*
20479584
MD
1135 * Check to see "how much" the page has been used and clear
1136 * the tracking access bits. If the object has no references
1137 * don't bother paying the expense.
984263bc
MD
1138 */
1139 actcount = 0;
1140 if (m->object->ref_count != 0) {
20479584
MD
1141 if (m->flags & PG_REFERENCED)
1142 ++actcount;
984263bc
MD
1143 actcount += pmap_ts_referenced(m);
1144 if (actcount) {
1145 m->act_count += ACT_ADVANCE + actcount;
1146 if (m->act_count > ACT_MAX)
1147 m->act_count = ACT_MAX;
1148 }
1149 }
984263bc
MD
1150 vm_page_flag_clear(m, PG_REFERENCED);
1151
1152 /*
20479584 1153 * actcount is only valid if the object ref_count is non-zero.
984263bc 1154 */
20479584 1155 if (actcount && m->object->ref_count != 0) {
984263bc
MD
1156 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1157 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1158 } else {
1159 m->act_count -= min(m->act_count, ACT_DECLINE);
1160 if (vm_pageout_algorithm ||
1161 m->object->ref_count == 0 ||
20479584
MD
1162 m->act_count < pass + 1
1163 ) {
1164 /*
1165 * Deactivate the page. If we had a
1166 * shortage from our inactive scan try to
1167 * free (cache) the page instead.
e6e9a0c3
MD
1168 *
1169 * Don't just blindly cache the page if
1170 * we do not have a shortage from the
1171 * inactive scan, that could lead to
1172 * gigabytes being moved.
20479584
MD
1173 */
1174 --active_shortage;
1175 if (inactive_shortage > 0 ||
1176 m->object->ref_count == 0) {
1177 if (inactive_shortage > 0)
1178 ++recycle_count;
17cde63e 1179 vm_page_busy(m);
984263bc 1180 vm_page_protect(m, VM_PROT_NONE);
e6e9a0c3
MD
1181 if (m->dirty == 0 &&
1182 inactive_shortage > 0) {
20479584 1183 --inactive_shortage;
984263bc 1184 vm_page_cache(m);
c84c24da 1185 } else {
984263bc 1186 vm_page_deactivate(m);
a491077e 1187 vm_page_wakeup(m);
c84c24da 1188 }
984263bc
MD
1189 } else {
1190 vm_page_deactivate(m);
1191 }
1192 } else {
984263bc
MD
1193 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1194 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1195 }
1196 }
1197 m = next;
1198 }
1199
984263bc 1200 /*
cd3c66bd
MD
1201 * The number of actually free pages can drop down to v_free_reserved,
1202 * we try to build the free count back above v_free_min. Note that
1203 * vm_paging_needed() also returns TRUE if v_free_count is not at
1204 * least v_free_min so that is the minimum we must build the free
1205 * count to.
1206 *
1207 * We use a slightly higher target to improve hysteresis,
1208 * ((v_free_target + v_free_min) / 2). Since v_free_target
1209 * is usually the same as v_cache_min this maintains about
1210 * half the pages in the free queue as are in the cache queue,
1211 * providing pretty good pipelining for pageout operation.
1212 *
1213 * The system operator can manipulate vm.v_cache_min and
1214 * vm.v_free_target to tune the pageout demon. Be sure
1215 * to keep vm.v_free_min < vm.v_free_target.
1216 *
1217 * Note that the original paging target is to get at least
1218 * (free_min + cache_min) into (free + cache). The slightly
1219 * higher target will shift additional pages from cache to free
1220 * without effecting the original paging target in order to
1221 * maintain better hysteresis and not have the free count always
1222 * be dead-on v_free_min.
06ecca5a 1223 *
5fd012e0 1224 * NOTE: we are still in a critical section.
c84c24da
MD
1225 *
1226 * Pages moved from PQ_CACHE to totally free are not counted in the
1227 * pages_freed counter.
984263bc 1228 */
cd3c66bd
MD
1229 while (vmstats.v_free_count <
1230 (vmstats.v_free_min + vmstats.v_free_target) / 2) {
1231 /*
1232 *
1233 */
984263bc
MD
1234 static int cache_rover = 0;
1235 m = vm_page_list_find(PQ_CACHE, cache_rover, FALSE);
20479584 1236 if (m == NULL)
984263bc
MD
1237 break;
1238 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) ||
1239 m->busy ||
1240 m->hold_count ||
1241 m->wire_count) {
1242#ifdef INVARIANTS
086c1d7e 1243 kprintf("Warning: busy page %p found in cache\n", m);
984263bc
MD
1244#endif
1245 vm_page_deactivate(m);
1246 continue;
1247 }
17cde63e
MD
1248 KKASSERT((m->flags & PG_MAPPED) == 0);
1249 KKASSERT(m->dirty == 0);
984263bc
MD
1250 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK;
1251 vm_pageout_page_free(m);
12e4aaff 1252 mycpu->gd_cnt.v_dfree++;
984263bc 1253 }
06ecca5a 1254
5fd012e0 1255 crit_exit();
984263bc
MD
1256
1257#if !defined(NO_SWAPPING)
1258 /*
1259 * Idle process swapout -- run once per second.
1260 */
1261 if (vm_swap_idle_enabled) {
1262 static long lsec;
1263 if (time_second != lsec) {
1264 vm_pageout_req_swapout |= VM_SWAP_IDLE;
1265 vm_req_vmdaemon();
1266 lsec = time_second;
1267 }
1268 }
1269#endif
1270
1271 /*
1272 * If we didn't get enough free pages, and we have skipped a vnode
1273 * in a writeable object, wakeup the sync daemon. And kick swapout
1274 * if we did not get enough free pages.
1275 */
1276 if (vm_paging_target() > 0) {
20479584 1277 if (vnodes_skipped && vm_page_count_min(0))
418ff780 1278 speedup_syncer();
984263bc
MD
1279#if !defined(NO_SWAPPING)
1280 if (vm_swap_enabled && vm_page_count_target()) {
1281 vm_req_vmdaemon();
1282 vm_pageout_req_swapout |= VM_SWAP_NORMAL;
1283 }
1284#endif
1285 }
1286
1287 /*
20479584
MD
1288 * Handle catastrophic conditions. Under good conditions we should
1289 * be at the target, well beyond our minimum. If we could not even
1290 * reach our minimum the system is under heavy stress.
1291 *
1292 * Determine whether we have run out of memory. This occurs when
1293 * swap_pager_full is TRUE and the only pages left in the page
1294 * queues are dirty. We will still likely have page shortages.
c84c24da
MD
1295 *
1296 * - swap_pager_full is set if insufficient swap was
1297 * available to satisfy a requested pageout.
1298 *
20479584
MD
1299 * - the inactive queue is bloated (4 x size of active queue),
1300 * meaning it is unable to get rid of dirty pages and.
c84c24da 1301 *
20479584
MD
1302 * - vm_page_count_min() without counting pages recycled from the
1303 * active queue (recycle_count) means we could not recover
1304 * enough pages to meet bare minimum needs. This test only
1305 * works if the inactive queue is bloated.
c84c24da 1306 *
20479584
MD
1307 * - due to a positive inactive_shortage we shifted the remaining
1308 * dirty pages from the active queue to the inactive queue
1309 * trying to find clean ones to free.
984263bc 1310 */
20479584 1311 if (swap_pager_full && vm_page_count_min(recycle_count))
c84c24da 1312 kprintf("Warning: system low on memory+swap!\n");
20479584
MD
1313 if (swap_pager_full && vm_page_count_min(recycle_count) &&
1314 vmstats.v_inactive_count > vmstats.v_active_count * 4 &&
1315 inactive_shortage > 0) {
1316 /*
1317 * Kill something.
1318 */
8fa76237
MD
1319 info.bigproc = NULL;
1320 info.bigsize = 0;
1321 allproc_scan(vm_pageout_scan_callback, &info);
1322 if (info.bigproc != NULL) {
1323 killproc(info.bigproc, "out of swap space");
1324 info.bigproc->p_nice = PRIO_MIN;
08f2f1bb
SS
1325 info.bigproc->p_usched->resetpriority(
1326 FIRST_LWP_IN_PROC(info.bigproc));
12e4aaff 1327 wakeup(&vmstats.v_free_count);
8fa76237 1328 PRELE(info.bigproc);
984263bc
MD
1329 }
1330 }
20479584 1331 return(inactive_shortage);
984263bc
MD
1332}
1333
99ad9bc4
MD
1334/*
1335 * The caller must hold vm_token and proc_token.
1336 */
8fa76237
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1337static int
1338vm_pageout_scan_callback(struct proc *p, void *data)
1339{
1340 struct vm_pageout_scan_info *info = data;
1341 vm_offset_t size;
1342
1343 /*
20479584
MD
1344 * Never kill system processes or init. If we have configured swap
1345 * then try to avoid killing low-numbered pids.
8fa76237
MD
1346 */
1347 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) ||
1348 ((p->p_pid < 48) && (vm_swap_size != 0))) {
1349 return (0);
1350 }
1351
1352 /*
1353 * if the process is in a non-running type state,
1354 * don't touch it.
1355 */
20479584 1356 if (p->p_stat != SACTIVE && p->p_stat != SSTOP)
8fa76237 1357 return (0);
8fa76237
MD
1358
1359 /*
20479584
MD
1360 * Get the approximate process size. Note that anonymous pages
1361 * with backing swap will be counted twice, but there should not
1362 * be too many such pages due to the stress the VM system is
1363 * under at this point.
8fa76237 1364 */
20479584 1365 size = vmspace_anonymous_count(p->p_vmspace) +
8fa76237
MD
1366 vmspace_swap_count(p->p_vmspace);
1367
1368 /*
1369 * If the this process is bigger than the biggest one
1370 * remember it.
1371 */
20479584 1372 if (info->bigsize < size) {
8fa76237
MD
1373 if (info->bigproc)
1374 PRELE(info->bigproc);
1375 PHOLD(p);
1376 info->bigproc = p;
1377 info->bigsize = size;
1378 }
1379 return(0);
1380}
1381
984263bc
MD
1382/*
1383 * This routine tries to maintain the pseudo LRU active queue,
1384 * so that during long periods of time where there is no paging,
1385 * that some statistic accumulation still occurs. This code
1386 * helps the situation where paging just starts to occur.
99ad9bc4
MD
1387 *
1388 * The caller must hold vm_token.
984263bc
MD
1389 */
1390static void
57e43348 1391vm_pageout_page_stats(void)
984263bc 1392{
984263bc
MD
1393 vm_page_t m,next;
1394 int pcount,tpcount; /* Number of pages to check */
1395 static int fullintervalcount = 0;
1396 int page_shortage;
984263bc
MD
1397
1398 page_shortage =
12e4aaff
MD
1399 (vmstats.v_inactive_target + vmstats.v_cache_max + vmstats.v_free_min) -
1400 (vmstats.v_free_count + vmstats.v_inactive_count + vmstats.v_cache_count);
984263bc
MD
1401
1402 if (page_shortage <= 0)
1403 return;
1404
5fd012e0 1405 crit_enter();
984263bc 1406
12e4aaff 1407 pcount = vmstats.v_active_count;
984263bc
MD
1408 fullintervalcount += vm_pageout_stats_interval;
1409 if (fullintervalcount < vm_pageout_full_stats_interval) {
12e4aaff 1410 tpcount = (vm_pageout_stats_max * vmstats.v_active_count) / vmstats.v_page_count;
984263bc
MD
1411 if (pcount > tpcount)
1412 pcount = tpcount;
1413 } else {
1414 fullintervalcount = 0;
1415 }
1416
1417 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl);
1418 while ((m != NULL) && (pcount-- > 0)) {
1419 int actcount;
1420
1421 if (m->queue != PQ_ACTIVE) {
1422 break;
1423 }
1424
1425 next = TAILQ_NEXT(m, pageq);
1426 /*
1427 * Don't deactivate pages that are busy.
1428 */
1429 if ((m->busy != 0) ||
1430 (m->flags & PG_BUSY) ||
1431 (m->hold_count != 0)) {
984263bc
MD
1432 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1433 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1434 m = next;
1435 continue;
1436 }
1437
1438 actcount = 0;
1439 if (m->flags & PG_REFERENCED) {
1440 vm_page_flag_clear(m, PG_REFERENCED);
1441 actcount += 1;
1442 }
1443
1444 actcount += pmap_ts_referenced(m);
1445 if (actcount) {
1446 m->act_count += ACT_ADVANCE + actcount;
1447 if (m->act_count > ACT_MAX)
1448 m->act_count = ACT_MAX;
984263bc
MD
1449 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1450 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1451 } else {
1452 if (m->act_count == 0) {
1453 /*
1454 * We turn off page access, so that we have
1455 * more accurate RSS stats. We don't do this
1456 * in the normal page deactivation when the
1457 * system is loaded VM wise, because the
1458 * cost of the large number of page protect
1459 * operations would be higher than the value
1460 * of doing the operation.
1461 */
17cde63e 1462 vm_page_busy(m);
984263bc
MD
1463 vm_page_protect(m, VM_PROT_NONE);
1464 vm_page_deactivate(m);
a491077e 1465 vm_page_wakeup(m);
984263bc
MD
1466 } else {
1467 m->act_count -= min(m->act_count, ACT_DECLINE);
984263bc
MD
1468 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
1469 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE].pl, m, pageq);
984263bc
MD
1470 }
1471 }
1472
1473 m = next;
1474 }
5fd012e0 1475 crit_exit();
984263bc
MD
1476}
1477
99ad9bc4
MD
1478/*
1479 * The caller must hold vm_token.
1480 */
984263bc 1481static int
57e43348 1482vm_pageout_free_page_calc(vm_size_t count)
984263bc 1483{
12e4aaff 1484 if (count < vmstats.v_page_count)
984263bc
MD
1485 return 0;
1486 /*
1487 * free_reserved needs to include enough for the largest swap pager
1488 * structures plus enough for any pv_entry structs when paging.
1489 */
12e4aaff
MD
1490 if (vmstats.v_page_count > 1024)
1491 vmstats.v_free_min = 4 + (vmstats.v_page_count - 1024) / 200;
984263bc 1492 else
12e4aaff
MD
1493 vmstats.v_free_min = 4;
1494 vmstats.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE +
1495 vmstats.v_interrupt_free_min;
1496 vmstats.v_free_reserved = vm_pageout_page_count +
1497 vmstats.v_pageout_free_min + (count / 768) + PQ_L2_SIZE;
1498 vmstats.v_free_severe = vmstats.v_free_min / 2;
1499 vmstats.v_free_min += vmstats.v_free_reserved;
1500 vmstats.v_free_severe += vmstats.v_free_reserved;
984263bc
MD
1501 return 1;
1502}
1503
1504
1505/*
20479584 1506 * vm_pageout is the high level pageout daemon.
99ad9bc4
MD
1507 *
1508 * No requirements.
984263bc
MD
1509 */
1510static void
cd8ab232 1511vm_pageout_thread(void)
984263bc
MD
1512{
1513 int pass;
20479584 1514 int inactive_shortage;
984263bc 1515
99ad9bc4
MD
1516 /*
1517 * Permanently hold vm_token.
1518 */
1519 lwkt_gettoken(&vm_token);
1520
984263bc
MD
1521 /*
1522 * Initialize some paging parameters.
1523 */
4ecf7cc9 1524 curthread->td_flags |= TDF_SYSTHREAD;
984263bc 1525
12e4aaff
MD
1526 vmstats.v_interrupt_free_min = 2;
1527 if (vmstats.v_page_count < 2000)
984263bc
MD
1528 vm_pageout_page_count = 8;
1529
12e4aaff 1530 vm_pageout_free_page_calc(vmstats.v_page_count);
20479584 1531
984263bc
MD
1532 /*
1533 * v_free_target and v_cache_min control pageout hysteresis. Note
1534 * that these are more a measure of the VM cache queue hysteresis
1535 * then the VM free queue. Specifically, v_free_target is the
1536 * high water mark (free+cache pages).
1537 *
1538 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the
1539 * low water mark, while v_free_min is the stop. v_cache_min must
1540 * be big enough to handle memory needs while the pageout daemon
1541 * is signalled and run to free more pages.
1542 */
12e4aaff
MD
1543 if (vmstats.v_free_count > 6144)
1544 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved;
984263bc 1545 else
12e4aaff 1546 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved;
984263bc 1547
0e8bd897
MD
1548 /*
1549 * NOTE: With the new buffer cache b_act_count we want the default
1550 * inactive target to be a percentage of available memory.
1551 *
1552 * The inactive target essentially determines the minimum
1553 * number of 'temporary' pages capable of caching one-time-use
1554 * files when the VM system is otherwise full of pages
1555 * belonging to multi-time-use files or active program data.
51db7ca2
MD
1556 *
1557 * NOTE: The inactive target is aggressively persued only if the
1558 * inactive queue becomes too small. If the inactive queue
1559 * is large enough to satisfy page movement to free+cache
1560 * then it is repopulated more slowly from the active queue.
e15708fc 1561 * This allows a general inactive_target default to be set.
51db7ca2
MD
1562 *
1563 * There is an issue here for processes which sit mostly idle
1564 * 'overnight', such as sshd, tcsh, and X. Any movement from
1565 * the active queue will eventually cause such pages to
1566 * recycle eventually causing a lot of paging in the morning.
1567 * To reduce the incidence of this pages cycled out of the
1568 * buffer cache are moved directly to the inactive queue if
e15708fc
MD
1569 * they were only used once or twice.
1570 *
1571 * The vfs.vm_cycle_point sysctl can be used to adjust this.
1572 * Increasing the value (up to 64) increases the number of
1573 * buffer recyclements which go directly to the inactive queue.
0e8bd897 1574 */
12e4aaff
MD
1575 if (vmstats.v_free_count > 2048) {
1576 vmstats.v_cache_min = vmstats.v_free_target;
1577 vmstats.v_cache_max = 2 * vmstats.v_cache_min;
984263bc 1578 } else {
12e4aaff
MD
1579 vmstats.v_cache_min = 0;
1580 vmstats.v_cache_max = 0;
984263bc 1581 }
e15708fc 1582 vmstats.v_inactive_target = vmstats.v_free_count / 4;
984263bc
MD
1583
1584 /* XXX does not really belong here */
1585 if (vm_page_max_wired == 0)
12e4aaff 1586 vm_page_max_wired = vmstats.v_free_count / 3;
984263bc
MD
1587
1588 if (vm_pageout_stats_max == 0)
12e4aaff 1589 vm_pageout_stats_max = vmstats.v_free_target;
984263bc
MD
1590
1591 /*
1592 * Set interval in seconds for stats scan.
1593 */
1594 if (vm_pageout_stats_interval == 0)
1595 vm_pageout_stats_interval = 5;
1596 if (vm_pageout_full_stats_interval == 0)
1597 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4;
1598
1599
1600 /*
1601 * Set maximum free per pass
1602 */
1603 if (vm_pageout_stats_free_max == 0)
1604 vm_pageout_stats_free_max = 5;
1605
1606 swap_pager_swap_init();
1607 pass = 0;
20479584 1608
984263bc
MD
1609 /*
1610 * The pageout daemon is never done, so loop forever.
1611 */
1612 while (TRUE) {
1613 int error;
984263bc 1614
12d8aca7 1615 /*
1bfac262
MD
1616 * Wait for an action request. If we timeout check to
1617 * see if paging is needed (in case the normal wakeup
1618 * code raced us).
12d8aca7 1619 */
20479584 1620 if (vm_pages_needed == 0) {
984263bc 1621 error = tsleep(&vm_pages_needed,
20479584
MD
1622 0, "psleep",
1623 vm_pageout_stats_interval * hz);
1bfac262
MD
1624 if (error &&
1625 vm_paging_needed() == 0 &&
1626 vm_pages_needed == 0) {
984263bc
MD
1627 vm_pageout_page_stats();
1628 continue;
1629 }
20479584 1630 vm_pages_needed = 1;
984263bc
MD
1631 }
1632
20479584 1633 mycpu->gd_cnt.v_pdwakeups++;
20479584
MD
1634
1635 /*
12d8aca7
MD
1636 * Scan for pageout. Try to avoid thrashing the system
1637 * with activity.
20479584 1638 */
12d8aca7 1639 inactive_shortage = vm_pageout_scan(pass);
20479584
MD
1640 if (inactive_shortage > 0) {
1641 ++pass;
1642 if (swap_pager_full) {
1643 /*
1644 * Running out of memory, catastrophic back-off
1645 * to one-second intervals.
1646 */
1647 tsleep(&vm_pages_needed, 0, "pdelay", hz);
1648 } else if (pass < 10 && vm_pages_needed > 1) {
1649 /*
1650 * Normal operation, additional processes
1651 * have already kicked us. Retry immediately.
1652 */
1653 } else if (pass < 10) {
1654 /*
1655 * Normal operation, fewer processes. Delay
1656 * a bit but allow wakeups.
1657 */
1658 vm_pages_needed = 0;
1659 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10);
1660 vm_pages_needed = 1;
1661 } else {
1662 /*
1663 * We've taken too many passes, forced delay.
1664 */
1665 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10);
1666 }
1667 } else {
12d8aca7
MD
1668 /*
1669 * Interlocked wakeup of waiters (non-optional)
1670 */
20479584 1671 pass = 0;
12d8aca7
MD
1672 if (vm_pages_needed && !vm_page_count_min(0)) {
1673 wakeup(&vmstats.v_free_count);
1674 vm_pages_needed = 0;
1675 }
20479584 1676 }
984263bc
MD
1677 }
1678}
1679
cd8ab232
MD
1680static struct kproc_desc page_kp = {
1681 "pagedaemon",
1682 vm_pageout_thread,
1683 &pagethread
1684};
1685SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp)
1686
1687
20479584
MD
1688/*
1689 * Called after allocating a page out of the cache or free queue
1690 * to possibly wake the pagedaemon up to replentish our supply.
1691 *
1692 * We try to generate some hysteresis by waking the pagedaemon up
1bfac262
MD
1693 * when our free+cache pages go below the free_min+cache_min level.
1694 * The pagedaemon tries to get the count back up to at least the
1695 * minimum, and through to the target level if possible.
20479584
MD
1696 *
1697 * If the pagedaemon is already active bump vm_pages_needed as a hint
1698 * that there are even more requests pending.
99ad9bc4
MD
1699 *
1700 * SMP races ok?
1701 * No requirements.
20479584 1702 */
984263bc 1703void
57e43348 1704pagedaemon_wakeup(void)
984263bc 1705{
1bfac262 1706 if (vm_paging_needed() && curthread != pagethread) {
20479584 1707 if (vm_pages_needed == 0) {
1bfac262 1708 vm_pages_needed = 1; /* SMP race ok */
20479584
MD
1709 wakeup(&vm_pages_needed);
1710 } else if (vm_page_count_min(0)) {
1bfac262 1711 ++vm_pages_needed; /* SMP race ok */
20479584 1712 }
984263bc
MD
1713 }
1714}
1715
1716#if !defined(NO_SWAPPING)
99ad9bc4
MD
1717
1718/*
1719 * SMP races ok?
1720 * No requirements.
1721 */
984263bc 1722static void
57e43348 1723vm_req_vmdaemon(void)
984263bc
MD
1724{
1725 static int lastrun = 0;
1726
1727 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
1728 wakeup(&vm_daemon_needed);
1729 lastrun = ticks;
1730 }
1731}
1732
8fa76237
MD
1733static int vm_daemon_callback(struct proc *p, void *data __unused);
1734
99ad9bc4
MD
1735/*
1736 * No requirements.
1737 */
984263bc 1738static void
57e43348 1739vm_daemon(void)
984263bc 1740{
99ad9bc4
MD
1741 /*
1742 * Permanently hold vm_token.
1743 */
1744 lwkt_gettoken(&vm_token);
1745
984263bc 1746 while (TRUE) {
377d4740 1747 tsleep(&vm_daemon_needed, 0, "psleep", 0);
984263bc
MD
1748 if (vm_pageout_req_swapout) {
1749 swapout_procs(vm_pageout_req_swapout);
1750 vm_pageout_req_swapout = 0;
1751 }
1752 /*
1753 * scan the processes for exceeding their rlimits or if
1754 * process is swapped out -- deactivate pages
1755 */
8fa76237
MD
1756 allproc_scan(vm_daemon_callback, NULL);
1757 }
1758}
984263bc 1759
99ad9bc4
MD
1760/*
1761 * Caller must hold vm_token and proc_token.
1762 */
8fa76237
MD
1763static int
1764vm_daemon_callback(struct proc *p, void *data __unused)
1765{
1766 vm_pindex_t limit, size;
984263bc 1767
8fa76237
MD
1768 /*
1769 * if this is a system process or if we have already
1770 * looked at this process, skip it.
1771 */
1772 if (p->p_flag & (P_SYSTEM | P_WEXIT))
1773 return (0);
984263bc 1774
8fa76237
MD
1775 /*
1776 * if the process is in a non-running type state,
1777 * don't touch it.
1778 */
164b8401 1779 if (p->p_stat != SACTIVE && p->p_stat != SSTOP)
8fa76237 1780 return (0);
984263bc 1781
8fa76237
MD
1782 /*
1783 * get a limit
1784 */
1785 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur,
1786 p->p_rlimit[RLIMIT_RSS].rlim_max));
1787
1788 /*
1789 * let processes that are swapped out really be
1790 * swapped out. Set the limit to nothing to get as
1791 * many pages out to swap as possible.
1792 */
1793 if (p->p_flag & P_SWAPPEDOUT)
1794 limit = 0;
1795
1796 size = vmspace_resident_count(p->p_vmspace);
1797 if (limit >= 0 && size >= limit) {
1798 vm_pageout_map_deactivate_pages(
1799 &p->p_vmspace->vm_map, limit);
984263bc 1800 }
8fa76237 1801 return (0);
984263bc 1802}
8fa76237 1803
984263bc 1804#endif