blob: aa1139ccf3a7ef91d9e93a8aaa21bb340f665716 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/swap.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
6
7/*
Simon Arlott183ff222007-10-20 01:27:18 +02008 * This file contains the default values for the operation of the
Linus Torvalds1da177e2005-04-16 15:20:36 -07009 * Linux VM subsystem. Fine-tuning documentation can be found in
10 * Documentation/sysctl/vm.txt.
11 * Started 18.12.91
12 * Swap aging added 23.2.95, Stephen Tweedie.
13 * Buffermem limits added 12.3.98, Rik van Riel.
14 */
15
16#include <linux/mm.h>
17#include <linux/sched.h>
18#include <linux/kernel_stat.h>
19#include <linux/swap.h>
20#include <linux/mman.h>
21#include <linux/pagemap.h>
22#include <linux/pagevec.h>
23#include <linux/init.h>
24#include <linux/module.h>
25#include <linux/mm_inline.h>
26#include <linux/buffer_head.h> /* for try_to_release_page() */
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <linux/percpu_counter.h>
28#include <linux/percpu.h>
29#include <linux/cpu.h>
30#include <linux/notifier.h>
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -070031#include <linux/backing-dev.h>
Balbir Singh66e17072008-02-07 00:13:56 -080032#include <linux/memcontrol.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
34/* How many pages do we try to swap or page in/out together? */
35int page_cluster;
36
Hisashi Hifumi902aaed2007-10-16 01:24:52 -070037static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
38static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
39static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs) = { 0, };
40
Adrian Bunkb2213852006-09-25 23:31:02 -070041/*
42 * This path almost never happens for VM activity - pages are normally
43 * freed via pagevecs. But it gets used by networking.
44 */
Harvey Harrison920c7a52008-02-04 22:29:26 -080045static void __page_cache_release(struct page *page)
Adrian Bunkb2213852006-09-25 23:31:02 -070046{
47 if (PageLRU(page)) {
48 unsigned long flags;
49 struct zone *zone = page_zone(page);
50
51 spin_lock_irqsave(&zone->lru_lock, flags);
52 VM_BUG_ON(!PageLRU(page));
53 __ClearPageLRU(page);
54 del_page_from_lru(zone, page);
55 spin_unlock_irqrestore(&zone->lru_lock, flags);
56 }
57 free_hot_page(page);
58}
59
Nick Piggin8519fb32006-02-07 12:58:52 -080060static void put_compound_page(struct page *page)
61{
Christoph Lameterd85f3382007-05-06 14:49:39 -070062 page = compound_head(page);
Nick Piggin8519fb32006-02-07 12:58:52 -080063 if (put_page_testzero(page)) {
Andy Whitcroft33f2ef82006-12-06 20:33:32 -080064 compound_page_dtor *dtor;
Nick Piggin8519fb32006-02-07 12:58:52 -080065
Andy Whitcroft33f2ef82006-12-06 20:33:32 -080066 dtor = get_compound_page_dtor(page);
Nick Piggin8519fb32006-02-07 12:58:52 -080067 (*dtor)(page);
68 }
69}
70
Linus Torvalds1da177e2005-04-16 15:20:36 -070071void put_page(struct page *page)
72{
Nick Piggin8519fb32006-02-07 12:58:52 -080073 if (unlikely(PageCompound(page)))
74 put_compound_page(page);
75 else if (put_page_testzero(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 __page_cache_release(page);
77}
78EXPORT_SYMBOL(put_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070079
Alexander Zarochentsev1d7ea732006-08-13 23:24:27 -070080/**
Randy Dunlap76824862008-03-19 17:00:40 -070081 * put_pages_list() - release a list of pages
82 * @pages: list of pages threaded on page->lru
Alexander Zarochentsev1d7ea732006-08-13 23:24:27 -070083 *
84 * Release a list of pages which are strung together on page.lru. Currently
85 * used by read_cache_pages() and related error recovery code.
Alexander Zarochentsev1d7ea732006-08-13 23:24:27 -070086 */
87void put_pages_list(struct list_head *pages)
88{
89 while (!list_empty(pages)) {
90 struct page *victim;
91
92 victim = list_entry(pages->prev, struct page, lru);
93 list_del(&victim->lru);
94 page_cache_release(victim);
95 }
96}
97EXPORT_SYMBOL(put_pages_list);
98
Linus Torvalds1da177e2005-04-16 15:20:36 -070099/*
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700100 * pagevec_move_tail() must be called with IRQ disabled.
101 * Otherwise this may cause nasty races.
102 */
103static void pagevec_move_tail(struct pagevec *pvec)
104{
105 int i;
106 int pgmoved = 0;
107 struct zone *zone = NULL;
108
109 for (i = 0; i < pagevec_count(pvec); i++) {
110 struct page *page = pvec->pages[i];
111 struct zone *pagezone = page_zone(page);
112
113 if (pagezone != zone) {
114 if (zone)
115 spin_unlock(&zone->lru_lock);
116 zone = pagezone;
117 spin_lock(&zone->lru_lock);
118 }
119 if (PageLRU(page) && !PageActive(page)) {
120 list_move_tail(&page->lru, &zone->inactive_list);
121 pgmoved++;
122 }
123 }
124 if (zone)
125 spin_unlock(&zone->lru_lock);
126 __count_vm_events(PGROTATED, pgmoved);
127 release_pages(pvec->pages, pvec->nr, pvec->cold);
128 pagevec_reinit(pvec);
129}
130
131/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 * Writeback is about to end against a page which has been marked for immediate
133 * reclaim. If it still appears to be reclaimable, move it to the tail of the
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700134 * inactive list.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 *
136 * Returns zero if it cleared PG_writeback.
137 */
138int rotate_reclaimable_page(struct page *page)
139{
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700140 struct pagevec *pvec;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 unsigned long flags;
142
143 if (PageLocked(page))
144 return 1;
145 if (PageDirty(page))
146 return 1;
147 if (PageActive(page))
148 return 1;
149 if (!PageLRU(page))
150 return 1;
151
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700152 page_cache_get(page);
153 local_irq_save(flags);
154 pvec = &__get_cpu_var(lru_rotate_pvecs);
155 if (!pagevec_add(pvec, page))
156 pagevec_move_tail(pvec);
157 local_irq_restore(flags);
158
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 if (!test_clear_page_writeback(page))
160 BUG();
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700161
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 return 0;
163}
164
165/*
166 * FIXME: speed this up?
167 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800168void activate_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169{
170 struct zone *zone = page_zone(page);
171
172 spin_lock_irq(&zone->lru_lock);
173 if (PageLRU(page) && !PageActive(page)) {
174 del_page_from_inactive_list(zone, page);
175 SetPageActive(page);
176 add_page_to_active_list(zone, page);
Christoph Lameterf8891e52006-06-30 01:55:45 -0700177 __count_vm_event(PGACTIVATE);
Hugh Dickins427d5412008-03-04 14:29:03 -0800178 mem_cgroup_move_lists(page, true);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 }
180 spin_unlock_irq(&zone->lru_lock);
181}
182
183/*
184 * Mark a page as having seen activity.
185 *
186 * inactive,unreferenced -> inactive,referenced
187 * inactive,referenced -> active,unreferenced
188 * active,unreferenced -> active,referenced
189 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800190void mark_page_accessed(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191{
192 if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
193 activate_page(page);
194 ClearPageReferenced(page);
195 } else if (!PageReferenced(page)) {
196 SetPageReferenced(page);
197 }
198}
199
200EXPORT_SYMBOL(mark_page_accessed);
201
202/**
203 * lru_cache_add: add a page to the page lists
204 * @page: the page to add
205 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800206void lru_cache_add(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207{
208 struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);
209
210 page_cache_get(page);
211 if (!pagevec_add(pvec, page))
212 __pagevec_lru_add(pvec);
213 put_cpu_var(lru_add_pvecs);
214}
215
Harvey Harrison920c7a52008-02-04 22:29:26 -0800216void lru_cache_add_active(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217{
218 struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs);
219
220 page_cache_get(page);
221 if (!pagevec_add(pvec, page))
222 __pagevec_lru_add_active(pvec);
223 put_cpu_var(lru_add_active_pvecs);
224}
225
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700226/*
227 * Drain pages out of the cpu's pagevecs.
228 * Either "cpu" is the current CPU, and preemption has already been
229 * disabled; or "cpu" is being hot-unplugged, and is already dead.
230 */
231static void drain_cpu_pagevecs(int cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232{
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700233 struct pagevec *pvec;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700235 pvec = &per_cpu(lru_add_pvecs, cpu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 if (pagevec_count(pvec))
237 __pagevec_lru_add(pvec);
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700238
Andrew Morton80bfed92006-01-06 00:11:14 -0800239 pvec = &per_cpu(lru_add_active_pvecs, cpu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 if (pagevec_count(pvec))
241 __pagevec_lru_add_active(pvec);
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700242
243 pvec = &per_cpu(lru_rotate_pvecs, cpu);
244 if (pagevec_count(pvec)) {
245 unsigned long flags;
246
247 /* No harm done if a racing interrupt already did this */
248 local_irq_save(flags);
249 pagevec_move_tail(pvec);
250 local_irq_restore(flags);
251 }
Andrew Morton80bfed92006-01-06 00:11:14 -0800252}
253
254void lru_add_drain(void)
255{
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700256 drain_cpu_pagevecs(get_cpu());
Andrew Morton80bfed92006-01-06 00:11:14 -0800257 put_cpu();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258}
259
Nick Piggin053837f2006-01-18 17:42:27 -0800260#ifdef CONFIG_NUMA
David Howellsc4028952006-11-22 14:57:56 +0000261static void lru_add_drain_per_cpu(struct work_struct *dummy)
Nick Piggin053837f2006-01-18 17:42:27 -0800262{
263 lru_add_drain();
264}
265
266/*
267 * Returns 0 for success
268 */
269int lru_add_drain_all(void)
270{
David Howellsc4028952006-11-22 14:57:56 +0000271 return schedule_on_each_cpu(lru_add_drain_per_cpu);
Nick Piggin053837f2006-01-18 17:42:27 -0800272}
273
274#else
275
276/*
277 * Returns 0 for success
278 */
279int lru_add_drain_all(void)
280{
281 lru_add_drain();
282 return 0;
283}
284#endif
285
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 * Batched page_cache_release(). Decrement the reference count on all the
288 * passed pages. If it fell to zero then remove the page from the LRU and
289 * free it.
290 *
291 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
292 * for the remainder of the operation.
293 *
294 * The locking in this function is against shrink_cache(): we recheck the
295 * page count inside the lock to see whether shrink_cache grabbed the page
296 * via the LRU. If it did, give up: shrink_cache will free it.
297 */
298void release_pages(struct page **pages, int nr, int cold)
299{
300 int i;
301 struct pagevec pages_to_free;
302 struct zone *zone = NULL;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700303 unsigned long uninitialized_var(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304
305 pagevec_init(&pages_to_free, cold);
306 for (i = 0; i < nr; i++) {
307 struct page *page = pages[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308
Nick Piggin8519fb32006-02-07 12:58:52 -0800309 if (unlikely(PageCompound(page))) {
310 if (zone) {
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700311 spin_unlock_irqrestore(&zone->lru_lock, flags);
Nick Piggin8519fb32006-02-07 12:58:52 -0800312 zone = NULL;
313 }
314 put_compound_page(page);
315 continue;
316 }
317
Nick Pigginb5810032005-10-29 18:16:12 -0700318 if (!put_page_testzero(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 continue;
320
Nick Piggin46453a62006-03-22 00:07:58 -0800321 if (PageLRU(page)) {
322 struct zone *pagezone = page_zone(page);
323 if (pagezone != zone) {
324 if (zone)
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700325 spin_unlock_irqrestore(&zone->lru_lock,
326 flags);
Nick Piggin46453a62006-03-22 00:07:58 -0800327 zone = pagezone;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700328 spin_lock_irqsave(&zone->lru_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 }
Nick Piggin725d7042006-09-25 23:30:55 -0700330 VM_BUG_ON(!PageLRU(page));
Nick Piggin67453912006-03-22 00:08:00 -0800331 __ClearPageLRU(page);
Nick Piggin46453a62006-03-22 00:07:58 -0800332 del_page_from_lru(zone, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 }
Nick Piggin46453a62006-03-22 00:07:58 -0800334
335 if (!pagevec_add(&pages_to_free, page)) {
336 if (zone) {
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700337 spin_unlock_irqrestore(&zone->lru_lock, flags);
Nick Piggin46453a62006-03-22 00:07:58 -0800338 zone = NULL;
339 }
340 __pagevec_free(&pages_to_free);
341 pagevec_reinit(&pages_to_free);
342 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 }
344 if (zone)
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700345 spin_unlock_irqrestore(&zone->lru_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346
347 pagevec_free(&pages_to_free);
348}
349
350/*
351 * The pages which we're about to release may be in the deferred lru-addition
352 * queues. That would prevent them from really being freed right now. That's
353 * OK from a correctness point of view but is inefficient - those pages may be
354 * cache-warm and we want to give them back to the page allocator ASAP.
355 *
356 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
357 * and __pagevec_lru_add_active() call release_pages() directly to avoid
358 * mutual recursion.
359 */
360void __pagevec_release(struct pagevec *pvec)
361{
362 lru_add_drain();
363 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
364 pagevec_reinit(pvec);
365}
366
Steve French7f285702005-11-01 10:22:55 -0800367EXPORT_SYMBOL(__pagevec_release);
368
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369/*
370 * pagevec_release() for pages which are known to not be on the LRU
371 *
372 * This function reinitialises the caller's pagevec.
373 */
374void __pagevec_release_nonlru(struct pagevec *pvec)
375{
376 int i;
377 struct pagevec pages_to_free;
378
379 pagevec_init(&pages_to_free, pvec->cold);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 for (i = 0; i < pagevec_count(pvec); i++) {
381 struct page *page = pvec->pages[i];
382
Nick Piggin725d7042006-09-25 23:30:55 -0700383 VM_BUG_ON(PageLRU(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 if (put_page_testzero(page))
385 pagevec_add(&pages_to_free, page);
386 }
387 pagevec_free(&pages_to_free);
388 pagevec_reinit(pvec);
389}
390
391/*
392 * Add the passed pages to the LRU, then drop the caller's refcount
393 * on them. Reinitialises the caller's pagevec.
394 */
395void __pagevec_lru_add(struct pagevec *pvec)
396{
397 int i;
398 struct zone *zone = NULL;
399
400 for (i = 0; i < pagevec_count(pvec); i++) {
401 struct page *page = pvec->pages[i];
402 struct zone *pagezone = page_zone(page);
403
404 if (pagezone != zone) {
405 if (zone)
406 spin_unlock_irq(&zone->lru_lock);
407 zone = pagezone;
408 spin_lock_irq(&zone->lru_lock);
409 }
Nick Piggin725d7042006-09-25 23:30:55 -0700410 VM_BUG_ON(PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -0800411 SetPageLRU(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 add_page_to_inactive_list(zone, page);
413 }
414 if (zone)
415 spin_unlock_irq(&zone->lru_lock);
416 release_pages(pvec->pages, pvec->nr, pvec->cold);
417 pagevec_reinit(pvec);
418}
419
420EXPORT_SYMBOL(__pagevec_lru_add);
421
422void __pagevec_lru_add_active(struct pagevec *pvec)
423{
424 int i;
425 struct zone *zone = NULL;
426
427 for (i = 0; i < pagevec_count(pvec); i++) {
428 struct page *page = pvec->pages[i];
429 struct zone *pagezone = page_zone(page);
430
431 if (pagezone != zone) {
432 if (zone)
433 spin_unlock_irq(&zone->lru_lock);
434 zone = pagezone;
435 spin_lock_irq(&zone->lru_lock);
436 }
Nick Piggin725d7042006-09-25 23:30:55 -0700437 VM_BUG_ON(PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -0800438 SetPageLRU(page);
Nick Piggin725d7042006-09-25 23:30:55 -0700439 VM_BUG_ON(PageActive(page));
Nick Piggin4c84cac2006-03-22 00:08:00 -0800440 SetPageActive(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 add_page_to_active_list(zone, page);
442 }
443 if (zone)
444 spin_unlock_irq(&zone->lru_lock);
445 release_pages(pvec->pages, pvec->nr, pvec->cold);
446 pagevec_reinit(pvec);
447}
448
449/*
450 * Try to drop buffers from the pages in a pagevec
451 */
452void pagevec_strip(struct pagevec *pvec)
453{
454 int i;
455
456 for (i = 0; i < pagevec_count(pvec); i++) {
457 struct page *page = pvec->pages[i];
458
459 if (PagePrivate(page) && !TestSetPageLocked(page)) {
Christoph Lameter5b40dc72006-03-16 23:04:07 -0800460 if (PagePrivate(page))
461 try_to_release_page(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 unlock_page(page);
463 }
464 }
465}
466
467/**
468 * pagevec_lookup - gang pagecache lookup
469 * @pvec: Where the resulting pages are placed
470 * @mapping: The address_space to search
471 * @start: The starting page index
472 * @nr_pages: The maximum number of pages
473 *
474 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
475 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
476 * reference against the pages in @pvec.
477 *
478 * The search returns a group of mapping-contiguous pages with ascending
479 * indexes. There may be holes in the indices due to not-present pages.
480 *
481 * pagevec_lookup() returns the number of pages which were found.
482 */
483unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
484 pgoff_t start, unsigned nr_pages)
485{
486 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
487 return pagevec_count(pvec);
488}
489
Christoph Hellwig78539fd2006-01-11 20:47:41 +1100490EXPORT_SYMBOL(pagevec_lookup);
491
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
493 pgoff_t *index, int tag, unsigned nr_pages)
494{
495 pvec->nr = find_get_pages_tag(mapping, index, tag,
496 nr_pages, pvec->pages);
497 return pagevec_count(pvec);
498}
499
Steve French7f285702005-11-01 10:22:55 -0800500EXPORT_SYMBOL(pagevec_lookup_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501
502#ifdef CONFIG_SMP
503/*
504 * We tolerate a little inaccuracy to avoid ping-ponging the counter between
505 * CPUs
506 */
507#define ACCT_THRESHOLD max(16, NR_CPUS * 2)
508
509static DEFINE_PER_CPU(long, committed_space) = 0;
510
511void vm_acct_memory(long pages)
512{
513 long *local;
514
515 preempt_disable();
516 local = &__get_cpu_var(committed_space);
517 *local += pages;
518 if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) {
519 atomic_add(*local, &vm_committed_space);
520 *local = 0;
521 }
522 preempt_enable();
523}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524
525#ifdef CONFIG_HOTPLUG_CPU
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526
527/* Drop the CPU's cached committed space back into the central pool. */
528static int cpu_swap_callback(struct notifier_block *nfb,
529 unsigned long action,
530 void *hcpu)
531{
532 long *committed;
533
534 committed = &per_cpu(committed_space, (long)hcpu);
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -0700535 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 atomic_add(*committed, &vm_committed_space);
537 *committed = 0;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700538 drain_cpu_pagevecs((long)hcpu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 }
540 return NOTIFY_OK;
541}
542#endif /* CONFIG_HOTPLUG_CPU */
543#endif /* CONFIG_SMP */
544
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545/*
546 * Perform any setup for the swap system
547 */
548void __init swap_setup(void)
549{
550 unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
551
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700552#ifdef CONFIG_SWAP
553 bdi_init(swapper_space.backing_dev_info);
554#endif
555
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 /* Use a smaller cluster for small-memory machines */
557 if (megs < 16)
558 page_cluster = 2;
559 else
560 page_cluster = 3;
561 /*
562 * Right now other parts of the system means that we
563 * _really_ don't want to cluster much more
564 */
Ingo Molnar02316062006-12-06 20:38:17 -0800565#ifdef CONFIG_HOTPLUG_CPU
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 hotcpu_notifier(cpu_swap_callback, 0);
Ingo Molnar02316062006-12-06 20:38:17 -0800567#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568}