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15637ed4 RG |
1 | /* |
2 | * Copyright (c) 1991 Regents of the University of California. | |
3 | * All rights reserved. | |
4 | * | |
5 | * This code is derived from software contributed to Berkeley by | |
6 | * The Mach Operating System project at Carnegie-Mellon University. | |
7 | * | |
8 | * Redistribution and use in source and binary forms, with or without | |
9 | * modification, are permitted provided that the following conditions | |
10 | * are met: | |
11 | * 1. Redistributions of source code must retain the above copyright | |
12 | * notice, this list of conditions and the following disclaimer. | |
13 | * 2. Redistributions in binary form must reproduce the above copyright | |
14 | * notice, this list of conditions and the following disclaimer in the | |
15 | * documentation and/or other materials provided with the distribution. | |
16 | * 3. All advertising materials mentioning features or use of this software | |
17 | * must display the following acknowledgement: | |
18 | * This product includes software developed by the University of | |
19 | * California, Berkeley and its contributors. | |
20 | * 4. Neither the name of the University nor the names of its contributors | |
21 | * may be used to endorse or promote products derived from this software | |
22 | * without specific prior written permission. | |
23 | * | |
24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
34 | * SUCH DAMAGE. | |
35 | * | |
36 | * @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 | |
37 | * | |
38 | * | |
39 | * Copyright (c) 1987, 1990 Carnegie-Mellon University. | |
40 | * All rights reserved. | |
41 | * | |
42 | * Authors: Avadis Tevanian, Jr., Michael Wayne Young | |
43 | * | |
44 | * Permission to use, copy, modify and distribute this software and | |
45 | * its documentation is hereby granted, provided that both the copyright | |
46 | * notice and this permission notice appear in all copies of the | |
47 | * software, derivative works or modified versions, and any portions | |
48 | * thereof, and that both notices appear in supporting documentation. | |
49 | * | |
50 | * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" | |
51 | * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND | |
52 | * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. | |
53 | * | |
54 | * Carnegie Mellon requests users of this software to return to | |
55 | * | |
56 | * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU | |
57 | * School of Computer Science | |
58 | * Carnegie Mellon University | |
59 | * Pittsburgh PA 15213-3890 | |
60 | * | |
61 | * any improvements or extensions that they make and grant Carnegie the | |
62 | * rights to redistribute these changes. | |
63 | * | |
64 | * PATCHES MAGIC LEVEL PATCH THAT GOT US HERE | |
65 | * -------------------- ----- ---------------------- | |
66 | * CURRENT PATCH LEVEL: 1 00137 | |
67 | * -------------------- ----- ---------------------- | |
68 | * | |
69 | * 20 Aug 92 David Greenman Removed un-necessary call to | |
70 | * swapout_thread | |
71 | * 08 Aug 93 Paul Kranenburg Add counters for vmstat | |
72 | */ | |
73 | ||
74 | /* | |
75 | * The proverbial page-out daemon. | |
76 | */ | |
77 | ||
78 | #include "param.h" | |
79 | ||
80 | #include "vm.h" | |
81 | #include "vm_page.h" | |
82 | #include "vm_pageout.h" | |
83 | #include "vmmeter.h" | |
84 | ||
85 | int vm_pages_needed; /* Event on which pageout daemon sleeps */ | |
86 | int vm_pageout_free_min = 0; /* Stop pageout to wait for pagers at this free level */ | |
87 | ||
88 | int vm_page_free_min_sanity = 40; | |
89 | ||
90 | int vm_page_pagesfreed; /* Pages freed by page daemon */ | |
91 | ||
92 | /* | |
93 | * vm_pageout_scan does the dirty work for the pageout daemon. | |
94 | */ | |
95 | vm_pageout_scan() | |
96 | { | |
97 | register vm_page_t m; | |
98 | register int page_shortage; | |
99 | register int s; | |
100 | register int pages_freed; | |
101 | int free; | |
102 | ||
103 | /* | |
104 | * Only continue when we want more pages to be "free" | |
105 | */ | |
106 | ||
107 | s = splimp(); | |
108 | simple_lock(&vm_page_queue_free_lock); | |
109 | free = vm_page_free_count; | |
110 | simple_unlock(&vm_page_queue_free_lock); | |
111 | splx(s); | |
112 | ||
113 | if (free < vm_page_free_target) { | |
114 | #ifdef OMIT | |
115 | swapout_threads(); | |
116 | #endif /* OMIT*/ | |
117 | ||
118 | /* | |
119 | * Be sure the pmap system is updated so | |
120 | * we can scan the inactive queue. | |
121 | */ | |
122 | ||
123 | pmap_update(); | |
124 | } | |
125 | ||
126 | /* | |
127 | * Acquire the resident page system lock, | |
128 | * as we may be changing what's resident quite a bit. | |
129 | */ | |
130 | vm_page_lock_queues(); | |
131 | ||
132 | /* | |
133 | * Start scanning the inactive queue for pages we can free. | |
134 | * We keep scanning until we have enough free pages or | |
135 | * we have scanned through the entire queue. If we | |
136 | * encounter dirty pages, we start cleaning them. | |
137 | */ | |
138 | ||
139 | pages_freed = 0; | |
140 | m = (vm_page_t) queue_first(&vm_page_queue_inactive); | |
141 | while (!queue_end(&vm_page_queue_inactive, (queue_entry_t) m)) { | |
142 | vm_page_t next; | |
143 | ||
144 | s = splimp(); | |
145 | simple_lock(&vm_page_queue_free_lock); | |
146 | free = vm_page_free_count; | |
147 | simple_unlock(&vm_page_queue_free_lock); | |
148 | splx(s); | |
149 | ||
150 | if (free >= vm_page_free_target) | |
151 | break; | |
152 | ||
153 | if (m->clean) { | |
154 | next = (vm_page_t) queue_next(&m->pageq); | |
155 | if (pmap_is_referenced(VM_PAGE_TO_PHYS(m))) { | |
156 | vm_page_activate(m); | |
157 | vm_stat.reactivations++; | |
158 | } | |
159 | else { | |
160 | register vm_object_t object; | |
161 | object = m->object; | |
162 | if (!vm_object_lock_try(object)) { | |
163 | /* | |
164 | * Can't lock object - | |
165 | * skip page. | |
166 | */ | |
167 | m = next; | |
168 | continue; | |
169 | } | |
170 | pmap_page_protect(VM_PAGE_TO_PHYS(m), | |
171 | VM_PROT_NONE); | |
172 | vm_page_free(m); /* will dequeue */ | |
173 | pages_freed++; | |
174 | vm_object_unlock(object); | |
175 | } | |
176 | m = next; | |
177 | } | |
178 | else { | |
179 | /* | |
180 | * If a page is dirty, then it is either | |
181 | * being washed (but not yet cleaned) | |
182 | * or it is still in the laundry. If it is | |
183 | * still in the laundry, then we start the | |
184 | * cleaning operation. | |
185 | */ | |
186 | ||
187 | if (m->laundry) { | |
188 | /* | |
189 | * Clean the page and remove it from the | |
190 | * laundry. | |
191 | * | |
192 | * We set the busy bit to cause | |
193 | * potential page faults on this page to | |
194 | * block. | |
195 | * | |
196 | * And we set pageout-in-progress to keep | |
197 | * the object from disappearing during | |
198 | * pageout. This guarantees that the | |
199 | * page won't move from the inactive | |
200 | * queue. (However, any other page on | |
201 | * the inactive queue may move!) | |
202 | */ | |
203 | ||
204 | register vm_object_t object; | |
205 | register vm_pager_t pager; | |
206 | int pageout_status; | |
207 | ||
208 | object = m->object; | |
209 | if (!vm_object_lock_try(object)) { | |
210 | /* | |
211 | * Skip page if we can't lock | |
212 | * its object | |
213 | */ | |
214 | m = (vm_page_t) queue_next(&m->pageq); | |
215 | continue; | |
216 | } | |
217 | ||
218 | pmap_page_protect(VM_PAGE_TO_PHYS(m), | |
219 | VM_PROT_NONE); | |
220 | m->busy = TRUE; | |
221 | vm_stat.pageouts++; | |
222 | ||
223 | /* | |
224 | * Try to collapse the object before | |
225 | * making a pager for it. We must | |
226 | * unlock the page queues first. | |
227 | */ | |
228 | vm_page_unlock_queues(); | |
229 | ||
230 | vm_object_collapse(object); | |
231 | ||
232 | object->paging_in_progress++; | |
233 | vm_object_unlock(object); | |
234 | ||
235 | /* | |
236 | * Do a wakeup here in case the following | |
237 | * operations block. | |
238 | */ | |
239 | thread_wakeup((int) &vm_page_free_count); | |
240 | ||
241 | /* | |
242 | * If there is no pager for the page, | |
243 | * use the default pager. If there's | |
244 | * no place to put the page at the | |
245 | * moment, leave it in the laundry and | |
246 | * hope that there will be paging space | |
247 | * later. | |
248 | */ | |
249 | ||
250 | if ((pager = object->pager) == NULL) { | |
251 | pager = vm_pager_allocate(PG_DFLT, | |
252 | (caddr_t)0, | |
253 | object->size, | |
254 | VM_PROT_ALL); | |
255 | if (pager != NULL) { | |
256 | vm_object_setpager(object, | |
257 | pager, 0, FALSE); | |
258 | } | |
259 | } | |
260 | pageout_status = pager ? | |
261 | vm_pager_put(pager, m, FALSE) : | |
262 | VM_PAGER_FAIL; | |
263 | vm_object_lock(object); | |
264 | vm_page_lock_queues(); | |
265 | next = (vm_page_t) queue_next(&m->pageq); | |
266 | ||
267 | switch (pageout_status) { | |
268 | case VM_PAGER_OK: | |
269 | case VM_PAGER_PEND: | |
270 | m->laundry = FALSE; | |
271 | break; | |
272 | case VM_PAGER_BAD: | |
273 | /* | |
274 | * Page outside of range of object. | |
275 | * Right now we essentially lose the | |
276 | * changes by pretending it worked. | |
277 | * XXX dubious, what should we do? | |
278 | */ | |
279 | m->laundry = FALSE; | |
280 | m->clean = TRUE; | |
281 | pmap_clear_modify(VM_PAGE_TO_PHYS(m)); | |
282 | break; | |
283 | case VM_PAGER_FAIL: | |
284 | /* | |
285 | * If page couldn't be paged out, then | |
286 | * reactivate the page so it doesn't | |
287 | * clog the inactive list. (We will | |
288 | * try paging out it again later). | |
289 | */ | |
290 | vm_page_activate(m); | |
291 | break; | |
292 | } | |
293 | ||
294 | pmap_clear_reference(VM_PAGE_TO_PHYS(m)); | |
295 | ||
296 | /* | |
297 | * If the operation is still going, leave | |
298 | * the page busy to block all other accesses. | |
299 | * Also, leave the paging in progress | |
300 | * indicator set so that we don't attempt an | |
301 | * object collapse. | |
302 | */ | |
303 | if (pageout_status != VM_PAGER_PEND) { | |
304 | m->busy = FALSE; | |
305 | PAGE_WAKEUP(m); | |
306 | object->paging_in_progress--; | |
307 | } | |
308 | thread_wakeup((int) object); | |
309 | vm_object_unlock(object); | |
310 | m = next; | |
311 | } | |
312 | else | |
313 | m = (vm_page_t) queue_next(&m->pageq); | |
314 | } | |
315 | } | |
316 | ||
317 | /* | |
318 | * Compute the page shortage. If we are still very low on memory | |
319 | * be sure that we will move a minimal amount of pages from active | |
320 | * to inactive. | |
321 | */ | |
322 | ||
323 | page_shortage = vm_page_inactive_target - vm_page_inactive_count; | |
324 | page_shortage -= vm_page_free_count; | |
325 | ||
326 | if ((page_shortage <= 0) && (pages_freed == 0)) | |
327 | page_shortage = 1; | |
328 | ||
329 | while (page_shortage > 0) { | |
330 | /* | |
331 | * Move some more pages from active to inactive. | |
332 | */ | |
333 | ||
334 | if (queue_empty(&vm_page_queue_active)) { | |
335 | break; | |
336 | } | |
337 | m = (vm_page_t) queue_first(&vm_page_queue_active); | |
338 | vm_page_deactivate(m); | |
339 | page_shortage--; | |
340 | } | |
341 | ||
342 | vm_page_pagesfreed += pages_freed; | |
343 | vm_page_unlock_queues(); | |
344 | } | |
345 | ||
346 | /* | |
347 | * vm_pageout is the high level pageout daemon. | |
348 | */ | |
349 | ||
350 | void vm_pageout() | |
351 | { | |
352 | (void) spl0(); | |
353 | ||
354 | /* | |
355 | * Initialize some paging parameters. | |
356 | */ | |
357 | ||
358 | if (vm_page_free_min == 0) { | |
359 | vm_page_free_min = vm_page_free_count / 20; | |
360 | if (vm_page_free_min < 3) | |
361 | vm_page_free_min = 3; | |
362 | ||
363 | if (vm_page_free_min > vm_page_free_min_sanity) | |
364 | vm_page_free_min = vm_page_free_min_sanity; | |
365 | } | |
366 | ||
367 | if (vm_page_free_reserved == 0) { | |
368 | if ((vm_page_free_reserved = vm_page_free_min / 2) < 10) | |
369 | vm_page_free_reserved = 10; | |
370 | } | |
371 | if (vm_pageout_free_min == 0) { | |
372 | if ((vm_pageout_free_min = vm_page_free_reserved / 2) > 10) | |
373 | vm_pageout_free_min = 10; | |
374 | } | |
375 | ||
376 | if (vm_page_free_target == 0) | |
377 | vm_page_free_target = (vm_page_free_min * 4) / 3; | |
378 | ||
379 | if (vm_page_inactive_target == 0) | |
380 | vm_page_inactive_target = vm_page_free_min * 2; | |
381 | ||
382 | if (vm_page_free_target <= vm_page_free_min) | |
383 | vm_page_free_target = vm_page_free_min + 1; | |
384 | ||
385 | if (vm_page_inactive_target <= vm_page_free_target) | |
386 | vm_page_inactive_target = vm_page_free_target + 1; | |
387 | ||
388 | /* | |
389 | * The pageout daemon is never done, so loop | |
390 | * forever. | |
391 | */ | |
392 | ||
393 | simple_lock(&vm_pages_needed_lock); | |
394 | while (TRUE) { | |
395 | thread_sleep((int) &vm_pages_needed, &vm_pages_needed_lock, | |
396 | FALSE); | |
397 | cnt.v_scan++; | |
398 | vm_pageout_scan(); | |
399 | vm_pager_sync(); | |
400 | simple_lock(&vm_pages_needed_lock); | |
401 | thread_wakeup((int) &vm_page_free_count); | |
402 | } | |
403 | } |