kernel - Fix p->p_lock race and remove unused procedures
[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>
b12defdc 97#include <sys/spinlock2.h>
12e4aaff 98#include <vm/vm_page2.h>
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99
100/*
101 * System initialization
102 */
103
104/* the kernel process "vm_pageout"*/
1388df65 105static int vm_pageout_clean (vm_page_t);
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);
984263bc 208#endif
027193eb 209static void vm_pageout_page_stats(int q);
984263bc 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.
238 */
984263bc 239static int
57e43348 240vm_pageout_clean(vm_page_t m)
984263bc 241{
5f910b2f 242 vm_object_t object;
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243 vm_page_t mc[2*vm_pageout_page_count];
244 int pageout_count;
b12defdc 245 int error;
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246 int ib, is, page_base;
247 vm_pindex_t pindex = m->pindex;
248
249 object = m->object;
250
251 /*
252 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP
253 * with the new swapper, but we could have serious problems paging
254 * out other object types if there is insufficient memory.
255 *
256 * Unfortunately, checking free memory here is far too late, so the
257 * check has been moved up a procedural level.
258 */
259
260 /*
261 * Don't mess with the page if it's busy, held, or special
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262 *
263 * XXX do we really need to check hold_count here? hold_count
264 * isn't supposed to mess with vm_page ops except prevent the
265 * page from being reused.
984263bc 266 */
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267 if (m->hold_count != 0 || (m->flags & PG_UNMANAGED)) {
268 vm_page_wakeup(m);
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269 return 0;
270 }
271
272 mc[vm_pageout_page_count] = m;
273 pageout_count = 1;
274 page_base = vm_pageout_page_count;
275 ib = 1;
276 is = 1;
277
278 /*
279 * Scan object for clusterable pages.
280 *
281 * We can cluster ONLY if: ->> the page is NOT
282 * clean, wired, busy, held, or mapped into a
283 * buffer, and one of the following:
284 * 1) The page is inactive, or a seldom used
285 * active page.
286 * -or-
287 * 2) we force the issue.
288 *
289 * During heavy mmap/modification loads the pageout
290 * daemon can really fragment the underlying file
291 * due to flushing pages out of order and not trying
292 * align the clusters (which leave sporatic out-of-order
293 * holes). To solve this problem we do the reverse scan
294 * first and attempt to align our cluster, then do a
295 * forward scan if room remains.
296 */
297
398c240d 298 vm_object_hold(object);
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299more:
300 while (ib && pageout_count < vm_pageout_page_count) {
301 vm_page_t p;
302
303 if (ib > pindex) {
304 ib = 0;
305 break;
306 }
307
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308 p = vm_page_lookup_busy_try(object, pindex - ib, TRUE, &error);
309 if (error || p == NULL) {
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310 ib = 0;
311 break;
312 }
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313 if ((p->queue - p->pc) == PQ_CACHE ||
314 (p->flags & PG_UNMANAGED)) {
315 vm_page_wakeup(p);
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316 ib = 0;
317 break;
318 }
319 vm_page_test_dirty(p);
320 if ((p->dirty & p->valid) == 0 ||
027193eb 321 p->queue - p->pc != PQ_INACTIVE ||
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322 p->wire_count != 0 || /* may be held by buf cache */
323 p->hold_count != 0) { /* may be undergoing I/O */
b12defdc 324 vm_page_wakeup(p);
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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
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343 p = vm_page_lookup_busy_try(object, pindex + is, TRUE, &error);
344 if (error || p == NULL)
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345 break;
346 if (((p->queue - p->pc) == PQ_CACHE) ||
347 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) {
b12defdc 348 vm_page_wakeup(p);
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349 break;
350 }
351 vm_page_test_dirty(p);
352 if ((p->dirty & p->valid) == 0 ||
027193eb 353 p->queue - p->pc != PQ_INACTIVE ||
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354 p->wire_count != 0 || /* may be held by buf cache */
355 p->hold_count != 0) { /* may be undergoing I/O */
b12defdc 356 vm_page_wakeup(p);
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357 break;
358 }
359 mc[page_base + pageout_count] = p;
360 ++pageout_count;
361 ++is;
362 }
363
364 /*
365 * If we exhausted our forward scan, continue with the reverse scan
366 * when possible, even past a page boundry. This catches boundry
367 * conditions.
368 */
369 if (ib && pageout_count < vm_pageout_page_count)
370 goto more;
371
398c240d
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372 vm_object_drop(object);
373
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374 /*
375 * we allow reads during pageouts...
376 */
377 return vm_pageout_flush(&mc[page_base], pageout_count, 0);
378}
379
380/*
381 * vm_pageout_flush() - launder the given pages
382 *
383 * The given pages are laundered. Note that we setup for the start of
384 * I/O ( i.e. busy the page ), mark it read-only, and bump the object
385 * reference count all in here rather then in the parent. If we want
386 * the parent to do more sophisticated things we may have to change
387 * the ordering.
99ad9bc4 388 *
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389 * The pages in the array must be busied by the caller and will be
390 * unbusied by this function.
984263bc 391 */
984263bc 392int
57e43348 393vm_pageout_flush(vm_page_t *mc, int count, int flags)
984263bc 394{
5f910b2f 395 vm_object_t object;
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396 int pageout_status[count];
397 int numpagedout = 0;
398 int i;
399
400 /*
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401 * Initiate I/O. Bump the vm_page_t->busy counter.
402 */
403 for (i = 0; i < count; i++) {
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404 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL,
405 ("vm_pageout_flush page %p index %d/%d: partially "
406 "invalid page", mc[i], i, count));
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407 vm_page_io_start(mc[i]);
408 }
409
410 /*
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411 * We must make the pages read-only. This will also force the
412 * modified bit in the related pmaps to be cleared. The pager
413 * cannot clear the bit for us since the I/O completion code
414 * typically runs from an interrupt. The act of making the page
415 * read-only handles the case for us.
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416 *
417 * Then we can unbusy the pages, we still hold a reference by virtue
418 * of our soft-busy.
984263bc 419 */
984263bc 420 for (i = 0; i < count; i++) {
984263bc 421 vm_page_protect(mc[i], VM_PROT_READ);
b12defdc 422 vm_page_wakeup(mc[i]);
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423 }
424
425 object = mc[0]->object;
426 vm_object_pip_add(object, count);
427
428 vm_pager_put_pages(object, mc, count,
c439ad8f 429 (flags | ((object == &kernel_object) ? VM_PAGER_PUT_SYNC : 0)),
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430 pageout_status);
431
432 for (i = 0; i < count; i++) {
433 vm_page_t mt = mc[i];
434
435 switch (pageout_status[i]) {
436 case VM_PAGER_OK:
437 numpagedout++;
438 break;
439 case VM_PAGER_PEND:
440 numpagedout++;
441 break;
442 case VM_PAGER_BAD:
443 /*
444 * Page outside of range of object. Right now we
445 * essentially lose the changes by pretending it
446 * worked.
447 */
b12defdc 448 vm_page_busy_wait(mt, FALSE, "pgbad");
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449 pmap_clear_modify(mt);
450 vm_page_undirty(mt);
b12defdc 451 vm_page_wakeup(mt);
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452 break;
453 case VM_PAGER_ERROR:
454 case VM_PAGER_FAIL:
455 /*
c84c24da
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456 * A page typically cannot be paged out when we
457 * have run out of swap. We leave the page
458 * marked inactive and will try to page it out
459 * again later.
460 *
461 * Starvation of the active page list is used to
462 * determine when the system is massively memory
463 * starved.
984263bc 464 */
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465 break;
466 case VM_PAGER_AGAIN:
467 break;
468 }
469
470 /*
471 * If the operation is still going, leave the page busy to
472 * block all other accesses. Also, leave the paging in
473 * progress indicator set so that we don't attempt an object
474 * collapse.
93afe6be
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475 *
476 * For any pages which have completed synchronously,
477 * deactivate the page if we are under a severe deficit.
478 * Do not try to enter them into the cache, though, they
479 * might still be read-heavy.
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480 */
481 if (pageout_status[i] != VM_PAGER_PEND) {
b12defdc 482 vm_page_busy_wait(mt, FALSE, "pgouw");
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483 if (vm_page_count_severe())
484 vm_page_deactivate(mt);
485#if 0
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486 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt))
487 vm_page_protect(mt, VM_PROT_READ);
93afe6be 488#endif
a491077e 489 vm_page_io_finish(mt);
b12defdc 490 vm_page_wakeup(mt);
a491077e 491 vm_object_pip_wakeup(object);
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492 }
493 }
494 return numpagedout;
495}
496
497#if !defined(NO_SWAPPING)
498/*
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499 * deactivate enough pages to satisfy the inactive target
500 * requirements or if vm_page_proc_limit is set, then
501 * deactivate all of the pages in the object and its
502 * backing_objects.
984263bc 503 *
99ad9bc4 504 * The map must be locked.
398c240d 505 * The caller must hold the vm_object.
984263bc 506 */
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507static int vm_pageout_object_deactivate_pages_callback(vm_page_t, void *);
508
984263bc 509static void
57e43348 510vm_pageout_object_deactivate_pages(vm_map_t map, vm_object_t object,
99ad9bc4 511 vm_pindex_t desired, int map_remove_only)
984263bc 512{
1f804340 513 struct rb_vm_page_scan_info info;
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514 vm_object_t lobject;
515 vm_object_t tobject;
984263bc 516 int remove_mode;
984263bc 517
05b9db80 518 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
b12defdc 519 lobject = object;
398c240d 520
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521 while (lobject) {
522 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
523 break;
524 if (lobject->type == OBJT_DEVICE || lobject->type == OBJT_PHYS)
525 break;
526 if (lobject->paging_in_progress)
527 break;
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528
529 remove_mode = map_remove_only;
b12defdc 530 if (lobject->shadow_count > 1)
984263bc 531 remove_mode = 1;
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532
533 /*
a5fc46c9
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534 * scan the objects entire memory queue. We hold the
535 * object's token so the scan should not race anything.
06ecca5a 536 */
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537 info.limit = remove_mode;
538 info.map = map;
539 info.desired = desired;
b12defdc 540 vm_page_rb_tree_RB_SCAN(&lobject->rb_memq, NULL,
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541 vm_pageout_object_deactivate_pages_callback,
542 &info
543 );
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544 while ((tobject = lobject->backing_object) != NULL) {
545 KKASSERT(tobject != object);
546 vm_object_hold(tobject);
547 if (tobject == lobject->backing_object)
548 break;
549 vm_object_drop(tobject);
550 }
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MD
551 if (lobject != object) {
552 vm_object_lock_swap();
b12defdc 553 vm_object_drop(lobject);
05b9db80 554 }
b12defdc 555 lobject = tobject;
1f804340 556 }
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557 if (lobject != object)
558 vm_object_drop(lobject);
1f804340 559}
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560
561/*
398c240d 562 * The caller must hold the vm_object.
99ad9bc4 563 */
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564static int
565vm_pageout_object_deactivate_pages_callback(vm_page_t p, void *data)
566{
567 struct rb_vm_page_scan_info *info = data;
568 int actcount;
984263bc 569
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570 if (pmap_resident_count(vm_map_pmap(info->map)) <= info->desired) {
571 return(-1);
572 }
573 mycpu->gd_cnt.v_pdpages++;
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574
575 if (vm_page_busy_try(p, TRUE))
576 return(0);
577 if (p->wire_count || p->hold_count || (p->flags & PG_UNMANAGED)) {
578 vm_page_wakeup(p);
579 return(0);
580 }
581 if (!pmap_page_exists_quick(vm_map_pmap(info->map), p)) {
582 vm_page_wakeup(p);
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583 return(0);
584 }
984263bc 585
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586 actcount = pmap_ts_referenced(p);
587 if (actcount) {
588 vm_page_flag_set(p, PG_REFERENCED);
589 } else if (p->flags & PG_REFERENCED) {
590 actcount = 1;
591 }
592
b12defdc 593 vm_page_and_queue_spin_lock(p);
027193eb 594 if (p->queue - p->pc != PQ_ACTIVE && (p->flags & PG_REFERENCED)) {
b12defdc 595 vm_page_and_queue_spin_unlock(p);
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596 vm_page_activate(p);
597 p->act_count += actcount;
598 vm_page_flag_clear(p, PG_REFERENCED);
027193eb 599 } else if (p->queue - p->pc == PQ_ACTIVE) {
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600 if ((p->flags & PG_REFERENCED) == 0) {
601 p->act_count -= min(p->act_count, ACT_DECLINE);
b12defdc
MD
602 if (!info->limit &&
603 (vm_pageout_algorithm || (p->act_count == 0))) {
604 vm_page_and_queue_spin_unlock(p);
984263bc 605 vm_page_protect(p, VM_PROT_NONE);
1f804340
MD
606 vm_page_deactivate(p);
607 } else {
027193eb
MD
608 TAILQ_REMOVE(&vm_page_queues[p->queue].pl,
609 p, pageq);
610 TAILQ_INSERT_TAIL(&vm_page_queues[p->queue].pl,
611 p, pageq);
b12defdc 612 vm_page_and_queue_spin_unlock(p);
984263bc 613 }
1f804340 614 } else {
b12defdc 615 vm_page_and_queue_spin_unlock(p);
1f804340
MD
616 vm_page_activate(p);
617 vm_page_flag_clear(p, PG_REFERENCED);
b12defdc
MD
618
619 vm_page_and_queue_spin_lock(p);
027193eb 620 if (p->queue - p->pc == PQ_ACTIVE) {
b12defdc
MD
621 if (p->act_count < (ACT_MAX - ACT_ADVANCE))
622 p->act_count += ACT_ADVANCE;
027193eb
MD
623 TAILQ_REMOVE(&vm_page_queues[p->queue].pl,
624 p, pageq);
625 TAILQ_INSERT_TAIL(&vm_page_queues[p->queue].pl,
626 p, pageq);
b12defdc
MD
627 }
628 vm_page_and_queue_spin_unlock(p);
984263bc 629 }
027193eb 630 } else if (p->queue - p->pc == PQ_INACTIVE) {
b12defdc 631 vm_page_and_queue_spin_unlock(p);
1f804340 632 vm_page_protect(p, VM_PROT_NONE);
b12defdc
MD
633 } else {
634 vm_page_and_queue_spin_unlock(p);
984263bc 635 }
b12defdc 636 vm_page_wakeup(p);
1f804340 637 return(0);
984263bc
MD
638}
639
640/*
99ad9bc4 641 * Deactivate some number of pages in a map, try to do it fairly, but
984263bc
MD
642 * that is really hard to do.
643 */
644static void
57e43348 645vm_pageout_map_deactivate_pages(vm_map_t map, vm_pindex_t desired)
984263bc
MD
646{
647 vm_map_entry_t tmpe;
648 vm_object_t obj, bigobj;
649 int nothingwired;
650
df4f70a6 651 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT)) {
984263bc
MD
652 return;
653 }
654
655 bigobj = NULL;
656 nothingwired = TRUE;
657
658 /*
659 * first, search out the biggest object, and try to free pages from
660 * that.
661 */
662 tmpe = map->header.next;
663 while (tmpe != &map->header) {
1b874851
MD
664 switch(tmpe->maptype) {
665 case VM_MAPTYPE_NORMAL:
666 case VM_MAPTYPE_VPAGETABLE:
984263bc
MD
667 obj = tmpe->object.vm_object;
668 if ((obj != NULL) && (obj->shadow_count <= 1) &&
669 ((bigobj == NULL) ||
670 (bigobj->resident_page_count < obj->resident_page_count))) {
671 bigobj = obj;
672 }
1b874851
MD
673 break;
674 default:
675 break;
984263bc
MD
676 }
677 if (tmpe->wired_count > 0)
678 nothingwired = FALSE;
679 tmpe = tmpe->next;
680 }
681
05b9db80
MD
682 if (bigobj) {
683 vm_object_hold(bigobj);
984263bc 684 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0);
05b9db80
MD
685 vm_object_drop(bigobj);
686 }
984263bc
MD
687
688 /*
689 * Next, hunt around for other pages to deactivate. We actually
690 * do this search sort of wrong -- .text first is not the best idea.
691 */
692 tmpe = map->header.next;
693 while (tmpe != &map->header) {
694 if (pmap_resident_count(vm_map_pmap(map)) <= desired)
695 break;
1b874851
MD
696 switch(tmpe->maptype) {
697 case VM_MAPTYPE_NORMAL:
698 case VM_MAPTYPE_VPAGETABLE:
984263bc 699 obj = tmpe->object.vm_object;
05b9db80
MD
700 if (obj) {
701 vm_object_hold(obj);
984263bc 702 vm_pageout_object_deactivate_pages(map, obj, desired, 0);
05b9db80
MD
703 vm_object_drop(obj);
704 }
1b874851
MD
705 break;
706 default:
707 break;
984263bc
MD
708 }
709 tmpe = tmpe->next;
710 };
711
712 /*
713 * Remove all mappings if a process is swapped out, this will free page
714 * table pages.
715 */
716 if (desired == 0 && nothingwired)
717 pmap_remove(vm_map_pmap(map),
88181b08 718 VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS);
984263bc 719 vm_map_unlock(map);
984263bc
MD
720}
721#endif
722
723/*
a5fc46c9
MD
724 * Called when the pageout scan wants to free a page. We no longer
725 * try to cycle the vm_object here with a reference & dealloc, which can
726 * cause a non-trivial object collapse in a critical path.
99ad9bc4 727 *
a5fc46c9
MD
728 * It is unclear why we cycled the ref_count in the past, perhaps to try
729 * to optimize shadow chain collapses but I don't quite see why it would
730 * be necessary. An OBJ_DEAD object should terminate any and all vm_pages
731 * synchronously and not have to be kicked-start.
984263bc 732 */
99ad9bc4 733static void
95813af0
MD
734vm_pageout_page_free(vm_page_t m)
735{
984263bc
MD
736 vm_page_protect(m, VM_PROT_NONE);
737 vm_page_free(m);
984263bc
MD
738}
739
740/*
20479584 741 * vm_pageout_scan does the dirty work for the pageout daemon.
984263bc 742 */
8fa76237
MD
743struct vm_pageout_scan_info {
744 struct proc *bigproc;
745 vm_offset_t bigsize;
746};
747
748static int vm_pageout_scan_callback(struct proc *p, void *data);
749
20479584 750static int
027193eb
MD
751vm_pageout_scan_inactive(int pass, int q, int inactive_shortage,
752 int *vnodes_skippedp)
984263bc 753{
b12defdc 754 vm_page_t m;
984263bc 755 struct vm_page marker;
5d6a945b 756 struct vnode *vpfailed; /* warning, allowed to be stale */
027193eb
MD
757 int maxscan;
758 int delta = 0;
984263bc
MD
759 vm_object_t object;
760 int actcount;
984263bc 761 int maxlaunder;
984263bc 762
984263bc
MD
763 /*
764 * Start scanning the inactive queue for pages we can move to the
765 * cache or free. The scan will stop when the target is reached or
766 * we have scanned the entire inactive queue. Note that m->act_count
767 * is not used to form decisions for the inactive queue, only for the
768 * active queue.
769 *
770 * maxlaunder limits the number of dirty pages we flush per scan.
771 * For most systems a smaller value (16 or 32) is more robust under
772 * extreme memory and disk pressure because any unnecessary writes
773 * to disk can result in extreme performance degredation. However,
774 * systems with excessive dirty pages (especially when MAP_NOSYNC is
775 * used) will die horribly with limited laundering. If the pageout
776 * daemon cannot clean enough pages in the first pass, we let it go
777 * all out in succeeding passes.
778 */
779 if ((maxlaunder = vm_max_launder) <= 1)
780 maxlaunder = 1;
781 if (pass)
782 maxlaunder = 10000;
783
06ecca5a 784 /*
b12defdc
MD
785 * Initialize our marker
786 */
787 bzero(&marker, sizeof(marker));
788 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER;
027193eb
MD
789 marker.queue = PQ_INACTIVE + q;
790 marker.pc = q;
b12defdc
MD
791 marker.wire_count = 1;
792
793 /*
794 * Inactive queue scan.
795 *
796 * NOTE: The vm_page must be spinlocked before the queue to avoid
797 * deadlocks, so it is easiest to simply iterate the loop
798 * with the queue unlocked at the top.
06ecca5a 799 */
5d6a945b 800 vpfailed = NULL;
b12defdc 801
027193eb
MD
802 vm_page_queues_spin_lock(PQ_INACTIVE + q);
803 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_INACTIVE + q].pl, &marker, pageq);
12e4aaff 804 maxscan = vmstats.v_inactive_count;
027193eb 805 vm_page_queues_spin_unlock(PQ_INACTIVE + q);
b12defdc
MD
806
807 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL &&
027193eb 808 maxscan-- > 0 && inactive_shortage - delta > 0)
b12defdc
MD
809 {
810 vm_page_and_queue_spin_lock(m);
811 if (m != TAILQ_NEXT(&marker, pageq)) {
812 vm_page_and_queue_spin_unlock(m);
813 ++maxscan;
814 continue;
815 }
027193eb
MD
816 KKASSERT(m->queue - m->pc == PQ_INACTIVE);
817 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl,
b12defdc 818 &marker, pageq);
027193eb 819 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE + q].pl, m,
b12defdc 820 &marker, pageq);
12e4aaff 821 mycpu->gd_cnt.v_pdpages++;
984263bc 822
06ecca5a 823 /*
b12defdc 824 * Skip marker pages
06ecca5a 825 */
b12defdc
MD
826 if (m->flags & PG_MARKER) {
827 vm_page_and_queue_spin_unlock(m);
828 continue;
829 }
984263bc
MD
830
831 /*
b12defdc
MD
832 * Try to busy the page. Don't mess with pages which are
833 * already busy or reorder them in the queue.
984263bc 834 */
b12defdc
MD
835 if (vm_page_busy_try(m, TRUE)) {
836 vm_page_and_queue_spin_unlock(m);
984263bc 837 continue;
b12defdc
MD
838 }
839 vm_page_and_queue_spin_unlock(m);
027193eb 840 KKASSERT(m->queue - m->pc == PQ_INACTIVE);
984263bc 841
d2d8515b
MD
842 lwkt_yield();
843
984263bc 844 /*
b12defdc
MD
845 * The page has been successfully busied and is now no
846 * longer spinlocked. The queue is no longer spinlocked
847 * either.
984263bc 848 */
06ecca5a 849
90244566
MD
850 /*
851 * It is possible for a page to be busied ad-hoc (e.g. the
852 * pmap_collect() code) and wired and race against the
853 * allocation of a new page. vm_page_alloc() may be forced
854 * to deactivate the wired page in which case it winds up
855 * on the inactive queue and must be handled here. We
856 * correct the problem simply by unqueuing the page.
857 */
858 if (m->wire_count) {
859 vm_page_unqueue_nowakeup(m);
860 vm_page_wakeup(m);
861 kprintf("WARNING: pagedaemon: wired page on "
862 "inactive queue %p\n", m);
863 continue;
864 }
865
984263bc 866 /*
b12defdc 867 * A held page may be undergoing I/O, so skip it.
984263bc 868 */
b12defdc
MD
869 if (m->hold_count) {
870 vm_page_and_queue_spin_lock(m);
027193eb
MD
871 if (m->queue - m->pc == PQ_INACTIVE) {
872 TAILQ_REMOVE(
873 &vm_page_queues[PQ_INACTIVE + q].pl,
874 m, pageq);
875 TAILQ_INSERT_TAIL(
876 &vm_page_queues[PQ_INACTIVE + q].pl,
877 m, pageq);
b12defdc
MD
878 }
879 vm_page_and_queue_spin_unlock(m);
880 ++vm_swapcache_inactive_heuristic;
881 vm_page_wakeup(m);
984263bc
MD
882 continue;
883 }
884
984263bc 885 if (m->object->ref_count == 0) {
06ecca5a
MD
886 /*
887 * If the object is not being used, we ignore previous
888 * references.
889 */
984263bc
MD
890 vm_page_flag_clear(m, PG_REFERENCED);
891 pmap_clear_reference(m);
b12defdc 892 /* fall through to end */
984263bc 893 } else if (((m->flags & PG_REFERENCED) == 0) &&
06ecca5a
MD
894 (actcount = pmap_ts_referenced(m))) {
895 /*
896 * Otherwise, if the page has been referenced while
897 * in the inactive queue, we bump the "activation
898 * count" upwards, making it less likely that the
899 * page will be added back to the inactive queue
900 * prematurely again. Here we check the page tables
901 * (or emulated bits, if any), given the upper level
902 * VM system not knowing anything about existing
903 * references.
904 */
984263bc
MD
905 vm_page_activate(m);
906 m->act_count += (actcount + ACT_ADVANCE);
b12defdc 907 vm_page_wakeup(m);
984263bc
MD
908 continue;
909 }
910
911 /*
b12defdc
MD
912 * (m) is still busied.
913 *
984263bc
MD
914 * If the upper level VM system knows about any page
915 * references, we activate the page. We also set the
916 * "activation count" higher than normal so that we will less
917 * likely place pages back onto the inactive queue again.
918 */
919 if ((m->flags & PG_REFERENCED) != 0) {
920 vm_page_flag_clear(m, PG_REFERENCED);
921 actcount = pmap_ts_referenced(m);
922 vm_page_activate(m);
923 m->act_count += (actcount + ACT_ADVANCE + 1);
b12defdc 924 vm_page_wakeup(m);
984263bc
MD
925 continue;
926 }
927
928 /*
929 * If the upper level VM system doesn't know anything about
930 * the page being dirty, we have to check for it again. As
931 * far as the VM code knows, any partially dirty pages are
932 * fully dirty.
41a01a4d
MD
933 *
934 * Pages marked PG_WRITEABLE may be mapped into the user
935 * address space of a process running on another cpu. A
936 * user process (without holding the MP lock) running on
937 * another cpu may be able to touch the page while we are
17cde63e
MD
938 * trying to remove it. vm_page_cache() will handle this
939 * case for us.
984263bc
MD
940 */
941 if (m->dirty == 0) {
942 vm_page_test_dirty(m);
943 } else {
944 vm_page_dirty(m);
945 }
946
984263bc 947 if (m->valid == 0) {
41a01a4d
MD
948 /*
949 * Invalid pages can be easily freed
950 */
984263bc 951 vm_pageout_page_free(m);
12e4aaff 952 mycpu->gd_cnt.v_dfree++;
027193eb 953 ++delta;
984263bc
MD
954 } else if (m->dirty == 0) {
955 /*
41a01a4d
MD
956 * Clean pages can be placed onto the cache queue.
957 * This effectively frees them.
984263bc
MD
958 */
959 vm_page_cache(m);
027193eb 960 ++delta;
984263bc
MD
961 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) {
962 /*
963 * Dirty pages need to be paged out, but flushing
964 * a page is extremely expensive verses freeing
965 * a clean page. Rather then artificially limiting
966 * the number of pages we can flush, we instead give
967 * dirty pages extra priority on the inactive queue
968 * by forcing them to be cycled through the queue
969 * twice before being flushed, after which the
970 * (now clean) page will cycle through once more
971 * before being freed. This significantly extends
972 * the thrash point for a heavily loaded machine.
973 */
984263bc 974 vm_page_flag_set(m, PG_WINATCFLS);
b12defdc 975 vm_page_and_queue_spin_lock(m);
027193eb
MD
976 if (m->queue - m->pc == PQ_INACTIVE) {
977 TAILQ_REMOVE(
978 &vm_page_queues[PQ_INACTIVE + q].pl,
979 m, pageq);
980 TAILQ_INSERT_TAIL(
981 &vm_page_queues[PQ_INACTIVE + q].pl,
982 m, pageq);
b12defdc
MD
983 }
984 vm_page_and_queue_spin_unlock(m);
e527fb6b 985 ++vm_swapcache_inactive_heuristic;
b12defdc 986 vm_page_wakeup(m);
984263bc
MD
987 } else if (maxlaunder > 0) {
988 /*
989 * We always want to try to flush some dirty pages if
990 * we encounter them, to keep the system stable.
991 * Normally this number is small, but under extreme
992 * pressure where there are insufficient clean pages
993 * on the inactive queue, we may have to go all out.
994 */
995 int swap_pageouts_ok;
996 struct vnode *vp = NULL;
997
998 object = m->object;
999
1000 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) {
1001 swap_pageouts_ok = 1;
1002 } else {
1003 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts);
1004 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts &&
20479584 1005 vm_page_count_min(0));
984263bc
MD
1006
1007 }
1008
1009 /*
1010 * We don't bother paging objects that are "dead".
1011 * Those objects are in a "rundown" state.
1012 */
1013 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) {
b12defdc 1014 vm_page_and_queue_spin_lock(m);
027193eb
MD
1015 if (m->queue - m->pc == PQ_INACTIVE) {
1016 TAILQ_REMOVE(
1017 &vm_page_queues[PQ_INACTIVE + q].pl,
1018 m, pageq);
1019 TAILQ_INSERT_TAIL(
1020 &vm_page_queues[PQ_INACTIVE + q].pl,
1021 m, pageq);
b12defdc
MD
1022 }
1023 vm_page_and_queue_spin_unlock(m);
e527fb6b 1024 ++vm_swapcache_inactive_heuristic;
b12defdc 1025 vm_page_wakeup(m);
984263bc
MD
1026 continue;
1027 }
1028
1029 /*
b12defdc
MD
1030 * (m) is still busied.
1031 *
984263bc
MD
1032 * The object is already known NOT to be dead. It
1033 * is possible for the vget() to block the whole
1034 * pageout daemon, but the new low-memory handling
1035 * code should prevent it.
1036 *
1037 * The previous code skipped locked vnodes and, worse,
1038 * reordered pages in the queue. This results in
1039 * completely non-deterministic operation because,
1040 * quite often, a vm_fault has initiated an I/O and
1041 * is holding a locked vnode at just the point where
1042 * the pageout daemon is woken up.
1043 *
1044 * We can't wait forever for the vnode lock, we might
1045 * deadlock due to a vn_read() getting stuck in
1046 * vm_wait while holding this vnode. We skip the
1047 * vnode if we can't get it in a reasonable amount
1048 * of time.
5d6a945b
MD
1049 *
1050 * vpfailed is used to (try to) avoid the case where
1051 * a large number of pages are associated with a
1052 * locked vnode, which could cause the pageout daemon
1053 * to stall for an excessive amount of time.
984263bc 1054 */
984263bc 1055 if (object->type == OBJT_VNODE) {
5d6a945b 1056 int flags;
984263bc 1057
5d6a945b
MD
1058 vp = object->handle;
1059 flags = LK_EXCLUSIVE | LK_NOOBJ;
1060 if (vp == vpfailed)
1061 flags |= LK_NOWAIT;
1062 else
1063 flags |= LK_TIMELOCK;
b12defdc
MD
1064 vm_page_hold(m);
1065 vm_page_wakeup(m);
1066
1067 /*
1068 * We have unbusied (m) temporarily so we can
1069 * acquire the vp lock without deadlocking.
1070 * (m) is held to prevent destruction.
1071 */
5d6a945b
MD
1072 if (vget(vp, flags) != 0) {
1073 vpfailed = vp;
984263bc
MD
1074 ++pageout_lock_miss;
1075 if (object->flags & OBJ_MIGHTBEDIRTY)
027193eb 1076 ++*vnodes_skippedp;
b12defdc 1077 vm_page_unhold(m);
984263bc
MD
1078 continue;
1079 }
1080
1081 /*
1082 * The page might have been moved to another
1083 * queue during potential blocking in vget()
1084 * above. The page might have been freed and
1085 * reused for another vnode. The object might
1086 * have been reused for another vnode.
1087 */
027193eb 1088 if (m->queue - m->pc != PQ_INACTIVE ||
984263bc
MD
1089 m->object != object ||
1090 object->handle != vp) {
1091 if (object->flags & OBJ_MIGHTBEDIRTY)
027193eb 1092 ++*vnodes_skippedp;
984263bc 1093 vput(vp);
b12defdc 1094 vm_page_unhold(m);
984263bc
MD
1095 continue;
1096 }
1097
1098 /*
1099 * The page may have been busied during the
1100 * blocking in vput(); We don't move the
1101 * page back onto the end of the queue so that
1102 * statistics are more correct if we don't.
1103 */
b12defdc 1104 if (vm_page_busy_try(m, TRUE)) {
984263bc 1105 vput(vp);
b12defdc 1106 vm_page_unhold(m);
984263bc
MD
1107 continue;
1108 }
b12defdc 1109 vm_page_unhold(m);
984263bc
MD
1110
1111 /*
b12defdc
MD
1112 * (m) is busied again
1113 *
1114 * We own the busy bit and remove our hold
1115 * bit. If the page is still held it
1116 * might be undergoing I/O, so skip it.
984263bc
MD
1117 */
1118 if (m->hold_count) {
b12defdc 1119 vm_page_and_queue_spin_lock(m);
027193eb
MD
1120 if (m->queue - m->pc == PQ_INACTIVE) {
1121 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, m, pageq);
1122 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_INACTIVE + q].pl, m, pageq);
b12defdc
MD
1123 }
1124 vm_page_and_queue_spin_unlock(m);
e527fb6b 1125 ++vm_swapcache_inactive_heuristic;
984263bc 1126 if (object->flags & OBJ_MIGHTBEDIRTY)
027193eb 1127 ++*vnodes_skippedp;
b12defdc 1128 vm_page_wakeup(m);
984263bc
MD
1129 vput(vp);
1130 continue;
1131 }
b12defdc 1132 /* (m) is left busied as we fall through */
984263bc
MD
1133 }
1134
1135 /*
b12defdc
MD
1136 * page is busy and not held here.
1137 *
984263bc
MD
1138 * If a page is dirty, then it is either being washed
1139 * (but not yet cleaned) or it is still in the
1140 * laundry. If it is still in the laundry, then we
1141 * start the cleaning operation.
1142 *
20479584
MD
1143 * decrement inactive_shortage on success to account
1144 * for the (future) cleaned page. Otherwise we
1145 * could wind up laundering or cleaning too many
1146 * pages.
984263bc 1147 */
984263bc 1148 if (vm_pageout_clean(m) != 0) {
027193eb 1149 ++delta;
984263bc 1150 --maxlaunder;
c84c24da 1151 }
b12defdc 1152 /* clean ate busy, page no longer accessible */
984263bc
MD
1153 if (vp != NULL)
1154 vput(vp);
b12defdc
MD
1155 } else {
1156 vm_page_wakeup(m);
984263bc
MD
1157 }
1158 }
027193eb
MD
1159 vm_page_queues_spin_lock(PQ_INACTIVE + q);
1160 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE + q].pl, &marker, pageq);
1161 vm_page_queues_spin_unlock(PQ_INACTIVE + q);
1162
1163 return (delta);
1164}
1165
1166static int
1167vm_pageout_scan_active(int pass, int q,
1168 int inactive_shortage, int active_shortage,
1169 int *recycle_countp)
1170{
1171 struct vm_page marker;
1172 vm_page_t m;
1173 int actcount;
1174 int delta = 0;
1175 int pcount;
984263bc
MD
1176
1177 /*
20479584
MD
1178 * We want to move pages from the active queue to the inactive
1179 * queue to get the inactive queue to the inactive target. If
1180 * we still have a page shortage from above we try to directly free
1181 * clean pages instead of moving them.
06ecca5a 1182 *
20479584
MD
1183 * If we do still have a shortage we keep track of the number of
1184 * pages we free or cache (recycle_count) as a measure of thrashing
1185 * between the active and inactive queues.
1186 *
51db7ca2
MD
1187 * If we were able to completely satisfy the free+cache targets
1188 * from the inactive pool we limit the number of pages we move
1189 * from the active pool to the inactive pool to 2x the pages we
e6e9a0c3
MD
1190 * had removed from the inactive pool (with a minimum of 1/5 the
1191 * inactive target). If we were not able to completely satisfy
1192 * the free+cache targets we go for the whole target aggressively.
20479584
MD
1193 *
1194 * NOTE: Both variables can end up negative.
1195 * NOTE: We are still in a critical section.
984263bc 1196 */
20479584 1197
027193eb
MD
1198 bzero(&marker, sizeof(marker));
1199 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER;
1200 marker.queue = PQ_ACTIVE + q;
1201 marker.pc = q;
1202 marker.wire_count = 1;
b12defdc 1203
027193eb
MD
1204 vm_page_queues_spin_lock(PQ_ACTIVE + q);
1205 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq);
1206 vm_page_queues_spin_unlock(PQ_ACTIVE + q);
b12defdc
MD
1207 pcount = vmstats.v_active_count;
1208
1209 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL &&
027193eb
MD
1210 pcount-- > 0 && (inactive_shortage - delta > 0 ||
1211 active_shortage > 0))
b12defdc
MD
1212 {
1213 vm_page_and_queue_spin_lock(m);
1214 if (m != TAILQ_NEXT(&marker, pageq)) {
1215 vm_page_and_queue_spin_unlock(m);
1216 ++pcount;
1217 continue;
1218 }
027193eb
MD
1219 KKASSERT(m->queue - m->pc == PQ_ACTIVE);
1220 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl,
b12defdc 1221 &marker, pageq);
027193eb 1222 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_ACTIVE + q].pl, m,
b12defdc 1223 &marker, pageq);
984263bc 1224
984263bc 1225 /*
b12defdc 1226 * Skip marker pages
984263bc 1227 */
b12defdc
MD
1228 if (m->flags & PG_MARKER) {
1229 vm_page_and_queue_spin_unlock(m);
1230 continue;
1231 }
06ecca5a 1232
984263bc 1233 /*
b12defdc
MD
1234 * Try to busy the page. Don't mess with pages which are
1235 * already busy or reorder them in the queue.
984263bc 1236 */
b12defdc
MD
1237 if (vm_page_busy_try(m, TRUE)) {
1238 vm_page_and_queue_spin_unlock(m);
984263bc
MD
1239 continue;
1240 }
1241
b12defdc
MD
1242 /*
1243 * Don't deactivate pages that are held, even if we can
1244 * busy them. (XXX why not?)
1245 */
1246 if (m->hold_count != 0) {
027193eb 1247 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl,
b12defdc 1248 m, pageq);
027193eb 1249 TAILQ_INSERT_TAIL(&vm_page_queues[PQ_ACTIVE + q].pl,
b12defdc
MD
1250 m, pageq);
1251 vm_page_and_queue_spin_unlock(m);
1252 vm_page_wakeup(m);
1253 continue;
1254 }
1255 vm_page_and_queue_spin_unlock(m);
d2d8515b 1256 lwkt_yield();
b12defdc
MD
1257
1258 /*
1259 * The page has been successfully busied and the page and
1260 * queue are no longer locked.
1261 */
1262
984263bc
MD
1263 /*
1264 * The count for pagedaemon pages is done after checking the
1265 * page for eligibility...
1266 */
12e4aaff 1267 mycpu->gd_cnt.v_pdpages++;
984263bc
MD
1268
1269 /*
20479584
MD
1270 * Check to see "how much" the page has been used and clear
1271 * the tracking access bits. If the object has no references
1272 * don't bother paying the expense.
984263bc
MD
1273 */
1274 actcount = 0;
1275 if (m->object->ref_count != 0) {
20479584
MD
1276 if (m->flags & PG_REFERENCED)
1277 ++actcount;
984263bc
MD
1278 actcount += pmap_ts_referenced(m);
1279 if (actcount) {
1280 m->act_count += ACT_ADVANCE + actcount;
1281 if (m->act_count > ACT_MAX)
1282 m->act_count = ACT_MAX;
1283 }
1284 }
984263bc
MD
1285 vm_page_flag_clear(m, PG_REFERENCED);
1286
1287 /*
20479584 1288 * actcount is only valid if the object ref_count is non-zero.
984263bc 1289 */
20479584 1290 if (actcount && m->object->ref_count != 0) {
b12defdc 1291 vm_page_and_queue_spin_lock(m);
027193eb
MD
1292 if (m->queue - m->pc == PQ_ACTIVE) {
1293 TAILQ_REMOVE(
1294 &vm_page_queues[PQ_ACTIVE + q].pl,
1295 m, pageq);
1296 TAILQ_INSERT_TAIL(
1297 &vm_page_queues[PQ_ACTIVE + q].pl,
1298 m, pageq);
b12defdc
MD
1299 }
1300 vm_page_and_queue_spin_unlock(m);
1301 vm_page_wakeup(m);
984263bc
MD
1302 } else {
1303 m->act_count -= min(m->act_count, ACT_DECLINE);
1304 if (vm_pageout_algorithm ||
1305 m->object->ref_count == 0 ||
20479584
MD
1306 m->act_count < pass + 1
1307 ) {
1308 /*
1309 * Deactivate the page. If we had a
1310 * shortage from our inactive scan try to
1311 * free (cache) the page instead.
e6e9a0c3
MD
1312 *
1313 * Don't just blindly cache the page if
1314 * we do not have a shortage from the
1315 * inactive scan, that could lead to
1316 * gigabytes being moved.
20479584
MD
1317 */
1318 --active_shortage;
027193eb 1319 if (inactive_shortage - delta > 0 ||
20479584 1320 m->object->ref_count == 0) {
027193eb
MD
1321 if (inactive_shortage - delta > 0)
1322 ++*recycle_countp;
984263bc 1323 vm_page_protect(m, VM_PROT_NONE);
e6e9a0c3 1324 if (m->dirty == 0 &&
027193eb
MD
1325 inactive_shortage - delta > 0) {
1326 ++delta;
984263bc 1327 vm_page_cache(m);
c84c24da 1328 } else {
984263bc 1329 vm_page_deactivate(m);
a491077e 1330 vm_page_wakeup(m);
c84c24da 1331 }
984263bc
MD
1332 } else {
1333 vm_page_deactivate(m);
b12defdc 1334 vm_page_wakeup(m);
984263bc
MD
1335 }
1336 } else {
b12defdc 1337 vm_page_and_queue_spin_lock(m);
027193eb 1338 if (m->queue - m->pc == PQ_ACTIVE) {
b12defdc 1339 TAILQ_REMOVE(
027193eb
MD
1340 &vm_page_queues[PQ_ACTIVE + q].pl,
1341 m, pageq);
b12defdc 1342 TAILQ_INSERT_TAIL(
027193eb
MD
1343 &vm_page_queues[PQ_ACTIVE + q].pl,
1344 m, pageq);
b12defdc
MD
1345 }
1346 vm_page_and_queue_spin_unlock(m);
1347 vm_page_wakeup(m);
984263bc
MD
1348 }
1349 }
984263bc
MD
1350 }
1351
b12defdc
MD
1352 /*
1353 * Clean out our local marker.
1354 */
027193eb
MD
1355 vm_page_queues_spin_lock(PQ_ACTIVE + q);
1356 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq);
1357 vm_page_queues_spin_unlock(PQ_ACTIVE + q);
1358
1359 return (delta);
1360}
1361
1362/*
1363 * The number of actually free pages can drop down to v_free_reserved,
1364 * we try to build the free count back above v_free_min. Note that
1365 * vm_paging_needed() also returns TRUE if v_free_count is not at
1366 * least v_free_min so that is the minimum we must build the free
1367 * count to.
1368 *
1369 * We use a slightly higher target to improve hysteresis,
1370 * ((v_free_target + v_free_min) / 2). Since v_free_target
1371 * is usually the same as v_cache_min this maintains about
1372 * half the pages in the free queue as are in the cache queue,
1373 * providing pretty good pipelining for pageout operation.
1374 *
1375 * The system operator can manipulate vm.v_cache_min and
1376 * vm.v_free_target to tune the pageout demon. Be sure
1377 * to keep vm.v_free_min < vm.v_free_target.
1378 *
1379 * Note that the original paging target is to get at least
1380 * (free_min + cache_min) into (free + cache). The slightly
1381 * higher target will shift additional pages from cache to free
1382 * without effecting the original paging target in order to
1383 * maintain better hysteresis and not have the free count always
1384 * be dead-on v_free_min.
1385 *
1386 * NOTE: we are still in a critical section.
1387 *
1388 * Pages moved from PQ_CACHE to totally free are not counted in the
1389 * pages_freed counter.
1390 */
1391static void
1392vm_pageout_scan_cache(int inactive_shortage,
1393 int vnodes_skipped, int recycle_count)
1394{
1395 struct vm_pageout_scan_info info;
1396 vm_page_t m;
b12defdc 1397
cd3c66bd
MD
1398 while (vmstats.v_free_count <
1399 (vmstats.v_free_min + vmstats.v_free_target) / 2) {
1400 /*
b12defdc 1401 * This steals some code from vm/vm_page.c
cd3c66bd 1402 */
984263bc 1403 static int cache_rover = 0;
b12defdc
MD
1404
1405 m = vm_page_list_find(PQ_CACHE, cache_rover & PQ_L2_MASK, FALSE);
20479584 1406 if (m == NULL)
984263bc 1407 break;
b12defdc
MD
1408 /* page is returned removed from its queue and spinlocked */
1409 if (vm_page_busy_try(m, TRUE)) {
1410 vm_page_deactivate_locked(m);
1411 vm_page_spin_unlock(m);
984263bc 1412#ifdef INVARIANTS
086c1d7e 1413 kprintf("Warning: busy page %p found in cache\n", m);
984263bc 1414#endif
b12defdc
MD
1415 continue;
1416 }
1417 vm_page_spin_unlock(m);
1418 pagedaemon_wakeup();
d2d8515b 1419 lwkt_yield();
b12defdc
MD
1420
1421 /*
1422 * Page has been successfully busied and it and its queue
1423 * is no longer spinlocked.
1424 */
1425 if ((m->flags & PG_UNMANAGED) ||
1426 m->hold_count ||
1427 m->wire_count) {
984263bc 1428 vm_page_deactivate(m);
b12defdc 1429 vm_page_wakeup(m);
984263bc
MD
1430 continue;
1431 }
17cde63e
MD
1432 KKASSERT((m->flags & PG_MAPPED) == 0);
1433 KKASSERT(m->dirty == 0);
b12defdc 1434 cache_rover += PQ_PRIME2;
984263bc 1435 vm_pageout_page_free(m);
12e4aaff 1436 mycpu->gd_cnt.v_dfree++;
984263bc 1437 }
06ecca5a 1438
984263bc
MD
1439#if !defined(NO_SWAPPING)
1440 /*
1441 * Idle process swapout -- run once per second.
1442 */
1443 if (vm_swap_idle_enabled) {
1444 static long lsec;
1445 if (time_second != lsec) {
1446 vm_pageout_req_swapout |= VM_SWAP_IDLE;
1447 vm_req_vmdaemon();
1448 lsec = time_second;
1449 }
1450 }
1451#endif
1452
1453 /*
1454 * If we didn't get enough free pages, and we have skipped a vnode
1455 * in a writeable object, wakeup the sync daemon. And kick swapout
1456 * if we did not get enough free pages.
1457 */
1458 if (vm_paging_target() > 0) {
20479584 1459 if (vnodes_skipped && vm_page_count_min(0))
418ff780 1460 speedup_syncer();
984263bc
MD
1461#if !defined(NO_SWAPPING)
1462 if (vm_swap_enabled && vm_page_count_target()) {
1463 vm_req_vmdaemon();
1464 vm_pageout_req_swapout |= VM_SWAP_NORMAL;
1465 }
1466#endif
1467 }
1468
1469 /*
20479584
MD
1470 * Handle catastrophic conditions. Under good conditions we should
1471 * be at the target, well beyond our minimum. If we could not even
1472 * reach our minimum the system is under heavy stress.
1473 *
1474 * Determine whether we have run out of memory. This occurs when
1475 * swap_pager_full is TRUE and the only pages left in the page
1476 * queues are dirty. We will still likely have page shortages.
c84c24da
MD
1477 *
1478 * - swap_pager_full is set if insufficient swap was
1479 * available to satisfy a requested pageout.
1480 *
20479584
MD
1481 * - the inactive queue is bloated (4 x size of active queue),
1482 * meaning it is unable to get rid of dirty pages and.
c84c24da 1483 *
20479584
MD
1484 * - vm_page_count_min() without counting pages recycled from the
1485 * active queue (recycle_count) means we could not recover
1486 * enough pages to meet bare minimum needs. This test only
1487 * works if the inactive queue is bloated.
c84c24da 1488 *
20479584
MD
1489 * - due to a positive inactive_shortage we shifted the remaining
1490 * dirty pages from the active queue to the inactive queue
1491 * trying to find clean ones to free.
984263bc 1492 */
20479584 1493 if (swap_pager_full && vm_page_count_min(recycle_count))
c84c24da 1494 kprintf("Warning: system low on memory+swap!\n");
20479584
MD
1495 if (swap_pager_full && vm_page_count_min(recycle_count) &&
1496 vmstats.v_inactive_count > vmstats.v_active_count * 4 &&
1497 inactive_shortage > 0) {
1498 /*
1499 * Kill something.
1500 */
8fa76237
MD
1501 info.bigproc = NULL;
1502 info.bigsize = 0;
1503 allproc_scan(vm_pageout_scan_callback, &info);
1504 if (info.bigproc != NULL) {
1505 killproc(info.bigproc, "out of swap space");
1506 info.bigproc->p_nice = PRIO_MIN;
08f2f1bb
SS
1507 info.bigproc->p_usched->resetpriority(
1508 FIRST_LWP_IN_PROC(info.bigproc));
12e4aaff 1509 wakeup(&vmstats.v_free_count);
8fa76237 1510 PRELE(info.bigproc);
984263bc
MD
1511 }
1512 }
1513}
1514
99ad9bc4 1515/*
b12defdc 1516 * The caller must hold proc_token.
99ad9bc4 1517 */
8fa76237
MD
1518static int
1519vm_pageout_scan_callback(struct proc *p, void *data)
1520{
1521 struct vm_pageout_scan_info *info = data;
1522 vm_offset_t size;
1523
1524 /*
20479584
MD
1525 * Never kill system processes or init. If we have configured swap
1526 * then try to avoid killing low-numbered pids.
8fa76237
MD
1527 */
1528 if ((p->p_flag & P_SYSTEM) || (p->p_pid == 1) ||
1529 ((p->p_pid < 48) && (vm_swap_size != 0))) {
1530 return (0);
1531 }
1532
1533 /*
1534 * if the process is in a non-running type state,
1535 * don't touch it.
1536 */
20479584 1537 if (p->p_stat != SACTIVE && p->p_stat != SSTOP)
8fa76237 1538 return (0);
8fa76237
MD
1539
1540 /*
20479584
MD
1541 * Get the approximate process size. Note that anonymous pages
1542 * with backing swap will be counted twice, but there should not
1543 * be too many such pages due to the stress the VM system is
1544 * under at this point.
8fa76237 1545 */
20479584 1546 size = vmspace_anonymous_count(p->p_vmspace) +
8fa76237
MD
1547 vmspace_swap_count(p->p_vmspace);
1548
1549 /*
1550 * If the this process is bigger than the biggest one
1551 * remember it.
1552 */
20479584 1553 if (info->bigsize < size) {
8fa76237
MD
1554 if (info->bigproc)
1555 PRELE(info->bigproc);
1556 PHOLD(p);
1557 info->bigproc = p;
1558 info->bigsize = size;
1559 }
d2d8515b 1560 lwkt_yield();
8fa76237
MD
1561 return(0);
1562}
1563
984263bc
MD
1564/*
1565 * This routine tries to maintain the pseudo LRU active queue,
1566 * so that during long periods of time where there is no paging,
1567 * that some statistic accumulation still occurs. This code
1568 * helps the situation where paging just starts to occur.
1569 */
1570static void
027193eb 1571vm_pageout_page_stats(int q)
984263bc 1572{
984263bc 1573 static int fullintervalcount = 0;
b12defdc
MD
1574 struct vm_page marker;
1575 vm_page_t m;
1576 int pcount, tpcount; /* Number of pages to check */
984263bc 1577 int page_shortage;
984263bc 1578
b12defdc
MD
1579 page_shortage = (vmstats.v_inactive_target + vmstats.v_cache_max +
1580 vmstats.v_free_min) -
1581 (vmstats.v_free_count + vmstats.v_inactive_count +
1582 vmstats.v_cache_count);
984263bc
MD
1583
1584 if (page_shortage <= 0)
1585 return;
1586
12e4aaff 1587 pcount = vmstats.v_active_count;
984263bc
MD
1588 fullintervalcount += vm_pageout_stats_interval;
1589 if (fullintervalcount < vm_pageout_full_stats_interval) {
b12defdc
MD
1590 tpcount = (vm_pageout_stats_max * vmstats.v_active_count) /
1591 vmstats.v_page_count;
984263bc
MD
1592 if (pcount > tpcount)
1593 pcount = tpcount;
1594 } else {
1595 fullintervalcount = 0;
1596 }
1597
b12defdc
MD
1598 bzero(&marker, sizeof(marker));
1599 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER;
027193eb
MD
1600 marker.queue = PQ_ACTIVE + q;
1601 marker.pc = q;
b12defdc
MD
1602 marker.wire_count = 1;
1603
027193eb
MD
1604 vm_page_queues_spin_lock(PQ_ACTIVE + q);
1605 TAILQ_INSERT_HEAD(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq);
1606 vm_page_queues_spin_unlock(PQ_ACTIVE + q);
b12defdc
MD
1607
1608 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL &&
1609 pcount-- > 0)
1610 {
984263bc
MD
1611 int actcount;
1612
b12defdc
MD
1613 vm_page_and_queue_spin_lock(m);
1614 if (m != TAILQ_NEXT(&marker, pageq)) {
1615 vm_page_and_queue_spin_unlock(m);
1616 ++pcount;
1617 continue;
984263bc 1618 }
027193eb
MD
1619 KKASSERT(m->queue - m->pc == PQ_ACTIVE);
1620 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq);
1621 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_ACTIVE + q].pl, m,
b12defdc 1622 &marker, pageq);
984263bc 1623
984263bc 1624 /*
b12defdc 1625 * Ignore markers
984263bc 1626 */
b12defdc
MD
1627 if (m->flags & PG_MARKER) {
1628 vm_page_and_queue_spin_unlock(m);
984263bc
MD
1629 continue;
1630 }
1631
b12defdc
MD
1632 /*
1633 * Ignore pages we can't busy
1634 */
1635 if (vm_page_busy_try(m, TRUE)) {
1636 vm_page_and_queue_spin_unlock(m);
1637 continue;
1638 }
1639 vm_page_and_queue_spin_unlock(m);
027193eb 1640 KKASSERT(m->queue - m->pc == PQ_ACTIVE);
b12defdc
MD
1641
1642 /*
1643 * We now have a safely busied page, the page and queue
1644 * spinlocks have been released.
1645 *
1646 * Ignore held pages
1647 */
1648 if (m->hold_count) {
1649 vm_page_wakeup(m);
1650 continue;
1651 }
1652
1653 /*
1654 * Calculate activity
1655 */
984263bc
MD
1656 actcount = 0;
1657 if (m->flags & PG_REFERENCED) {
1658 vm_page_flag_clear(m, PG_REFERENCED);
1659 actcount += 1;
1660 }
984263bc 1661 actcount += pmap_ts_referenced(m);
b12defdc
MD
1662
1663 /*
1664 * Update act_count and move page to end of queue.
1665 */
984263bc
MD
1666 if (actcount) {
1667 m->act_count += ACT_ADVANCE + actcount;
1668 if (m->act_count > ACT_MAX)
1669 m->act_count = ACT_MAX;
b12defdc 1670 vm_page_and_queue_spin_lock(m);
027193eb
MD
1671 if (m->queue - m->pc == PQ_ACTIVE) {
1672 TAILQ_REMOVE(
1673 &vm_page_queues[PQ_ACTIVE + q].pl,
1674 m, pageq);
1675 TAILQ_INSERT_TAIL(
1676 &vm_page_queues[PQ_ACTIVE + q].pl,
1677 m, pageq);
984263bc 1678 }
b12defdc
MD
1679 vm_page_and_queue_spin_unlock(m);
1680 vm_page_wakeup(m);
1681 continue;
984263bc
MD
1682 }
1683
b12defdc
MD
1684 if (m->act_count == 0) {
1685 /*
1686 * We turn off page access, so that we have
1687 * more accurate RSS stats. We don't do this
1688 * in the normal page deactivation when the
1689 * system is loaded VM wise, because the
1690 * cost of the large number of page protect
1691 * operations would be higher than the value
1692 * of doing the operation.
1693 *
1694 * We use the marker to save our place so
1695 * we can release the spin lock. both (m)
1696 * and (next) will be invalid.
1697 */
1698 vm_page_protect(m, VM_PROT_NONE);
1699 vm_page_deactivate(m);
1700 } else {
1701 m->act_count -= min(m->act_count, ACT_DECLINE);
1702 vm_page_and_queue_spin_lock(m);
027193eb
MD
1703 if (m->queue - m->pc == PQ_ACTIVE) {
1704 TAILQ_REMOVE(
1705 &vm_page_queues[PQ_ACTIVE + q].pl,
1706 m, pageq);
1707 TAILQ_INSERT_TAIL(
1708 &vm_page_queues[PQ_ACTIVE + q].pl,
1709 m, pageq);
b12defdc
MD
1710 }
1711 vm_page_and_queue_spin_unlock(m);
1712 }
1713 vm_page_wakeup(m);
984263bc 1714 }
b12defdc
MD
1715
1716 /*
1717 * Remove our local marker
1718 */
027193eb
MD
1719 vm_page_queues_spin_lock(PQ_ACTIVE + q);
1720 TAILQ_REMOVE(&vm_page_queues[PQ_ACTIVE + q].pl, &marker, pageq);
1721 vm_page_queues_spin_unlock(PQ_ACTIVE + q);
984263bc
MD
1722}
1723
1724static int
57e43348 1725vm_pageout_free_page_calc(vm_size_t count)
984263bc 1726{
12e4aaff 1727 if (count < vmstats.v_page_count)
984263bc
MD
1728 return 0;
1729 /*
1730 * free_reserved needs to include enough for the largest swap pager
1731 * structures plus enough for any pv_entry structs when paging.
0a4d4828
MD
1732 *
1733 * v_free_min normal allocations
1734 * v_free_reserved system allocations
1735 * v_pageout_free_min allocations by pageout daemon
1736 * v_interrupt_free_min low level allocations (e.g swap structures)
984263bc 1737 */
12e4aaff 1738 if (vmstats.v_page_count > 1024)
0a4d4828 1739 vmstats.v_free_min = 64 + (vmstats.v_page_count - 1024) / 200;
984263bc 1740 else
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1741 vmstats.v_free_min = 64;
1742 vmstats.v_free_reserved = vmstats.v_free_min * 4 / 8 + 7;
1743 vmstats.v_free_severe = vmstats.v_free_min * 4 / 8 + 0;
1744 vmstats.v_pageout_free_min = vmstats.v_free_min * 2 / 8 + 7;
1745 vmstats.v_interrupt_free_min = vmstats.v_free_min * 1 / 8 + 7;
1746
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1747 return 1;
1748}
1749
1750
1751/*
20479584 1752 * vm_pageout is the high level pageout daemon.
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1753 *
1754 * No requirements.
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1755 */
1756static void
cd8ab232 1757vm_pageout_thread(void)
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1758{
1759 int pass;
027193eb 1760 int q;
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1761
1762 /*
1763 * Initialize some paging parameters.
1764 */
4ecf7cc9 1765 curthread->td_flags |= TDF_SYSTHREAD;
984263bc 1766
12e4aaff 1767 if (vmstats.v_page_count < 2000)
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1768 vm_pageout_page_count = 8;
1769
12e4aaff 1770 vm_pageout_free_page_calc(vmstats.v_page_count);
20479584 1771
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1772 /*
1773 * v_free_target and v_cache_min control pageout hysteresis. Note
1774 * that these are more a measure of the VM cache queue hysteresis
1775 * then the VM free queue. Specifically, v_free_target is the
1776 * high water mark (free+cache pages).
1777 *
1778 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the
1779 * low water mark, while v_free_min is the stop. v_cache_min must
1780 * be big enough to handle memory needs while the pageout daemon
1781 * is signalled and run to free more pages.
1782 */
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1783 if (vmstats.v_free_count > 6144)
1784 vmstats.v_free_target = 4 * vmstats.v_free_min + vmstats.v_free_reserved;
984263bc 1785 else
12e4aaff 1786 vmstats.v_free_target = 2 * vmstats.v_free_min + vmstats.v_free_reserved;
984263bc 1787
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1788 /*
1789 * NOTE: With the new buffer cache b_act_count we want the default
1790 * inactive target to be a percentage of available memory.
1791 *
1792 * The inactive target essentially determines the minimum
1793 * number of 'temporary' pages capable of caching one-time-use
1794 * files when the VM system is otherwise full of pages
1795 * belonging to multi-time-use files or active program data.
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1796 *
1797 * NOTE: The inactive target is aggressively persued only if the
1798 * inactive queue becomes too small. If the inactive queue
1799 * is large enough to satisfy page movement to free+cache
1800 * then it is repopulated more slowly from the active queue.
e15708fc 1801 * This allows a general inactive_target default to be set.
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1802 *
1803 * There is an issue here for processes which sit mostly idle
1804 * 'overnight', such as sshd, tcsh, and X. Any movement from
1805 * the active queue will eventually cause such pages to
1806 * recycle eventually causing a lot of paging in the morning.
1807 * To reduce the incidence of this pages cycled out of the
1808 * buffer cache are moved directly to the inactive queue if
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1809 * they were only used once or twice.
1810 *
1811 * The vfs.vm_cycle_point sysctl can be used to adjust this.
1812 * Increasing the value (up to 64) increases the number of
1813 * buffer recyclements which go directly to the inactive queue.
0e8bd897 1814 */
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1815 if (vmstats.v_free_count > 2048) {
1816 vmstats.v_cache_min = vmstats.v_free_target;
1817 vmstats.v_cache_max = 2 * vmstats.v_cache_min;
984263bc 1818 } else {
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1819 vmstats.v_cache_min = 0;
1820 vmstats.v_cache_max = 0;
984263bc 1821 }
e15708fc 1822 vmstats.v_inactive_target = vmstats.v_free_count / 4;
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1823
1824 /* XXX does not really belong here */
1825 if (vm_page_max_wired == 0)
12e4aaff 1826 vm_page_max_wired = vmstats.v_free_count / 3;
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1827
1828 if (vm_pageout_stats_max == 0)
12e4aaff 1829 vm_pageout_stats_max = vmstats.v_free_target;
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1830
1831 /*
1832 * Set interval in seconds for stats scan.
1833 */
1834 if (vm_pageout_stats_interval == 0)
1835 vm_pageout_stats_interval = 5;
1836 if (vm_pageout_full_stats_interval == 0)
1837 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4;
1838
1839
1840 /*
1841 * Set maximum free per pass
1842 */
1843 if (vm_pageout_stats_free_max == 0)
1844 vm_pageout_stats_free_max = 5;
1845
1846 swap_pager_swap_init();
1847 pass = 0;
20479584 1848
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1849 /*
1850 * The pageout daemon is never done, so loop forever.
1851 */
1852 while (TRUE) {
1853 int error;
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1854 int delta1;
1855 int delta2;
1856 int inactive_shortage;
1857 int active_shortage;
1858 int vnodes_skipped = 0;
1859 int recycle_count = 0;
1860 int tmp;
984263bc 1861
12d8aca7 1862 /*
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1863 * Wait for an action request. If we timeout check to
1864 * see if paging is needed (in case the normal wakeup
1865 * code raced us).
12d8aca7 1866 */
20479584 1867 if (vm_pages_needed == 0) {
984263bc 1868 error = tsleep(&vm_pages_needed,
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MD
1869 0, "psleep",
1870 vm_pageout_stats_interval * hz);
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1871 if (error &&
1872 vm_paging_needed() == 0 &&
1873 vm_pages_needed == 0) {
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1874 for (q = 0; q < PQ_MAXL2_SIZE; ++q)
1875 vm_pageout_page_stats(q);
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1876 continue;
1877 }
20479584 1878 vm_pages_needed = 1;
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1879 }
1880
20479584 1881 mycpu->gd_cnt.v_pdwakeups++;
20479584 1882
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1883 /*
1884 * Do whatever cleanup that the pmap code can.
1885 */
1886 pmap_collect();
1887
20479584 1888 /*
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1889 * Scan for pageout. Try to avoid thrashing the system
1890 * with activity.
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1891 *
1892 * Calculate our target for the number of free+cache pages we
1893 * want to get to. This is higher then the number that causes
1894 * allocations to stall (severe) in order to provide hysteresis,
1895 * and if we don't make it all the way but get to the minimum
1896 * we're happy.
1897 */
1898 inactive_shortage = vm_paging_target() + vm_pageout_deficit;
1899 vm_pageout_deficit = 0;
1900 delta1 = 0;
1901 for (q = 0; q < PQ_MAXL2_SIZE; ++q) {
1902 delta1 += vm_pageout_scan_inactive(
1903 pass, q,
1904 inactive_shortage / PQ_MAXL2_SIZE + 1,
1905 &vnodes_skipped);
1906 }
1907
1908 /*
1909 * Figure out how many active pages we must deactivate. If
1910 * we were able to reach our target with just the inactive
1911 * scan above we limit the number of active pages we
1912 * deactivate to reduce unnecessary work.
1913 */
1914 active_shortage = vmstats.v_inactive_target -
1915 vmstats.v_inactive_count;
1916
1917 tmp = inactive_shortage;
1918 if (tmp < vmstats.v_inactive_target / 10)
1919 tmp = vmstats.v_inactive_target / 10;
1920 inactive_shortage -= delta1;
1921 if (inactive_shortage <= 0 && active_shortage > tmp * 2)
1922 active_shortage = tmp * 2;
1923
1924 delta2 = 0;
1925 for (q = 0; q < PQ_MAXL2_SIZE; ++q) {
1926 delta2 += vm_pageout_scan_active(
1927 pass, q,
1928 inactive_shortage / PQ_MAXL2_SIZE + 1,
1929 active_shortage / PQ_MAXL2_SIZE + 1,
1930 &recycle_count);
1931 }
1932
1933 /*
1934 * Finally free enough cache pages to meet our free page
1935 * requirement and take more drastic measures if we are
1936 * still in trouble.
1937 */
1938 inactive_shortage -= delta2;
1939 vm_pageout_scan_cache(inactive_shortage, vnodes_skipped,
1940 recycle_count);
1941
1942 /*
1943 * Wait for more work.
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1944 */
1945 if (inactive_shortage > 0) {
1946 ++pass;
1947 if (swap_pager_full) {
1948 /*
1949 * Running out of memory, catastrophic back-off
1950 * to one-second intervals.
1951 */
1952 tsleep(&vm_pages_needed, 0, "pdelay", hz);
1953 } else if (pass < 10 && vm_pages_needed > 1) {
1954 /*
1955 * Normal operation, additional processes
1956 * have already kicked us. Retry immediately.
1957 */
1958 } else if (pass < 10) {
1959 /*
1960 * Normal operation, fewer processes. Delay
1961 * a bit but allow wakeups.
1962 */
1963 vm_pages_needed = 0;
1964 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10);
1965 vm_pages_needed = 1;
1966 } else {
1967 /*
1968 * We've taken too many passes, forced delay.
1969 */
1970 tsleep(&vm_pages_needed, 0, "pdelay", hz / 10);
1971 }
1972 } else {
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1973 /*
1974 * Interlocked wakeup of waiters (non-optional)
1975 */
20479584 1976 pass = 0;
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1977 if (vm_pages_needed && !vm_page_count_min(0)) {
1978 wakeup(&vmstats.v_free_count);
1979 vm_pages_needed = 0;
1980 }
20479584 1981 }
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1982 }
1983}
1984
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1985static struct kproc_desc page_kp = {
1986 "pagedaemon",
1987 vm_pageout_thread,
1988 &pagethread
1989};
1990SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp)
1991
1992
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1993/*
1994 * Called after allocating a page out of the cache or free queue
1995 * to possibly wake the pagedaemon up to replentish our supply.
1996 *
1997 * We try to generate some hysteresis by waking the pagedaemon up
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1998 * when our free+cache pages go below the free_min+cache_min level.
1999 * The pagedaemon tries to get the count back up to at least the
2000 * minimum, and through to the target level if possible.
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2001 *
2002 * If the pagedaemon is already active bump vm_pages_needed as a hint
2003 * that there are even more requests pending.
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2004 *
2005 * SMP races ok?
2006 * No requirements.
20479584 2007 */
984263bc 2008void
57e43348 2009pagedaemon_wakeup(void)
984263bc 2010{
1bfac262 2011 if (vm_paging_needed() && curthread != pagethread) {
20479584 2012 if (vm_pages_needed == 0) {
1bfac262 2013 vm_pages_needed = 1; /* SMP race ok */
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MD
2014 wakeup(&vm_pages_needed);
2015 } else if (vm_page_count_min(0)) {
1bfac262 2016 ++vm_pages_needed; /* SMP race ok */
20479584 2017 }
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MD
2018 }
2019}
2020
2021#if !defined(NO_SWAPPING)
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2022
2023/*
2024 * SMP races ok?
2025 * No requirements.
2026 */
984263bc 2027static void
57e43348 2028vm_req_vmdaemon(void)
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MD
2029{
2030 static int lastrun = 0;
2031
2032 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
2033 wakeup(&vm_daemon_needed);
2034 lastrun = ticks;
2035 }
2036}
2037
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2038static int vm_daemon_callback(struct proc *p, void *data __unused);
2039
99ad9bc4
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2040/*
2041 * No requirements.
2042 */
984263bc 2043static void
57e43348 2044vm_daemon(void)
984263bc 2045{
99ad9bc4 2046 /*
b12defdc 2047 * XXX vm_daemon_needed specific token?
99ad9bc4 2048 */
984263bc 2049 while (TRUE) {
377d4740 2050 tsleep(&vm_daemon_needed, 0, "psleep", 0);
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MD
2051 if (vm_pageout_req_swapout) {
2052 swapout_procs(vm_pageout_req_swapout);
2053 vm_pageout_req_swapout = 0;
2054 }
2055 /*
2056 * scan the processes for exceeding their rlimits or if
2057 * process is swapped out -- deactivate pages
2058 */
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2059 allproc_scan(vm_daemon_callback, NULL);
2060 }
2061}
984263bc 2062
99ad9bc4 2063/*
b12defdc 2064 * Caller must hold proc_token.
99ad9bc4 2065 */
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MD
2066static int
2067vm_daemon_callback(struct proc *p, void *data __unused)
2068{
2069 vm_pindex_t limit, size;
984263bc 2070
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MD
2071 /*
2072 * if this is a system process or if we have already
2073 * looked at this process, skip it.
2074 */
2075 if (p->p_flag & (P_SYSTEM | P_WEXIT))
2076 return (0);
984263bc 2077
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2078 /*
2079 * if the process is in a non-running type state,
2080 * don't touch it.
2081 */
164b8401 2082 if (p->p_stat != SACTIVE && p->p_stat != SSTOP)
8fa76237 2083 return (0);
984263bc 2084
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MD
2085 /*
2086 * get a limit
2087 */
2088 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur,
2089 p->p_rlimit[RLIMIT_RSS].rlim_max));
2090
2091 /*
2092 * let processes that are swapped out really be
2093 * swapped out. Set the limit to nothing to get as
2094 * many pages out to swap as possible.
2095 */
2096 if (p->p_flag & P_SWAPPEDOUT)
2097 limit = 0;
2098
b12defdc 2099 lwkt_gettoken(&p->p_vmspace->vm_map.token);
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2100 size = vmspace_resident_count(p->p_vmspace);
2101 if (limit >= 0 && size >= limit) {
b12defdc 2102 vm_pageout_map_deactivate_pages(&p->p_vmspace->vm_map, limit);
984263bc 2103 }
b12defdc 2104 lwkt_reltoken(&p->p_vmspace->vm_map.token);
8fa76237 2105 return (0);
984263bc 2106}
8fa76237 2107
984263bc 2108#endif