blob: 9ac88323d237a82e9a6bf4a91fced71225a4e318 [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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
33/* How many pages do we try to swap or page in/out together? */
34int page_cluster;
35
Hisashi Hifumi902aaed2007-10-16 01:24:52 -070036static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
37static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
38static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs) = { 0, };
39
Adrian Bunkb2213852006-09-25 23:31:02 -070040/*
41 * This path almost never happens for VM activity - pages are normally
42 * freed via pagevecs. But it gets used by networking.
43 */
44static void fastcall __page_cache_release(struct page *page)
45{
46 if (PageLRU(page)) {
47 unsigned long flags;
48 struct zone *zone = page_zone(page);
49
50 spin_lock_irqsave(&zone->lru_lock, flags);
51 VM_BUG_ON(!PageLRU(page));
52 __ClearPageLRU(page);
53 del_page_from_lru(zone, page);
54 spin_unlock_irqrestore(&zone->lru_lock, flags);
55 }
56 free_hot_page(page);
57}
58
Nick Piggin8519fb32006-02-07 12:58:52 -080059static void put_compound_page(struct page *page)
60{
Christoph Lameterd85f3382007-05-06 14:49:39 -070061 page = compound_head(page);
Nick Piggin8519fb32006-02-07 12:58:52 -080062 if (put_page_testzero(page)) {
Andy Whitcroft33f2ef82006-12-06 20:33:32 -080063 compound_page_dtor *dtor;
Nick Piggin8519fb32006-02-07 12:58:52 -080064
Andy Whitcroft33f2ef82006-12-06 20:33:32 -080065 dtor = get_compound_page_dtor(page);
Nick Piggin8519fb32006-02-07 12:58:52 -080066 (*dtor)(page);
67 }
68}
69
Linus Torvalds1da177e2005-04-16 15:20:36 -070070void put_page(struct page *page)
71{
Nick Piggin8519fb32006-02-07 12:58:52 -080072 if (unlikely(PageCompound(page)))
73 put_compound_page(page);
74 else if (put_page_testzero(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 __page_cache_release(page);
76}
77EXPORT_SYMBOL(put_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070078
Alexander Zarochentsev1d7ea732006-08-13 23:24:27 -070079/**
80 * put_pages_list(): release a list of pages
81 *
82 * Release a list of pages which are strung together on page.lru. Currently
83 * used by read_cache_pages() and related error recovery code.
84 *
85 * @pages: list of pages threaded on page->lru
86 */
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 */
168void fastcall activate_page(struct page *page)
169{
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);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 }
179 spin_unlock_irq(&zone->lru_lock);
180}
181
182/*
183 * Mark a page as having seen activity.
184 *
185 * inactive,unreferenced -> inactive,referenced
186 * inactive,referenced -> active,unreferenced
187 * active,unreferenced -> active,referenced
188 */
189void fastcall mark_page_accessed(struct page *page)
190{
191 if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
192 activate_page(page);
193 ClearPageReferenced(page);
194 } else if (!PageReferenced(page)) {
195 SetPageReferenced(page);
196 }
197}
198
199EXPORT_SYMBOL(mark_page_accessed);
200
201/**
202 * lru_cache_add: add a page to the page lists
203 * @page: the page to add
204 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205void fastcall lru_cache_add(struct page *page)
206{
207 struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);
208
209 page_cache_get(page);
210 if (!pagevec_add(pvec, page))
211 __pagevec_lru_add(pvec);
212 put_cpu_var(lru_add_pvecs);
213}
214
215void fastcall lru_cache_add_active(struct page *page)
216{
217 struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs);
218
219 page_cache_get(page);
220 if (!pagevec_add(pvec, page))
221 __pagevec_lru_add_active(pvec);
222 put_cpu_var(lru_add_active_pvecs);
223}
224
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700225/*
226 * Drain pages out of the cpu's pagevecs.
227 * Either "cpu" is the current CPU, and preemption has already been
228 * disabled; or "cpu" is being hot-unplugged, and is already dead.
229 */
230static void drain_cpu_pagevecs(int cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231{
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700232 struct pagevec *pvec;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700234 pvec = &per_cpu(lru_add_pvecs, cpu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 if (pagevec_count(pvec))
236 __pagevec_lru_add(pvec);
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700237
Andrew Morton80bfed92006-01-06 00:11:14 -0800238 pvec = &per_cpu(lru_add_active_pvecs, cpu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 if (pagevec_count(pvec))
240 __pagevec_lru_add_active(pvec);
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700241
242 pvec = &per_cpu(lru_rotate_pvecs, cpu);
243 if (pagevec_count(pvec)) {
244 unsigned long flags;
245
246 /* No harm done if a racing interrupt already did this */
247 local_irq_save(flags);
248 pagevec_move_tail(pvec);
249 local_irq_restore(flags);
250 }
Andrew Morton80bfed92006-01-06 00:11:14 -0800251}
252
253void lru_add_drain(void)
254{
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700255 drain_cpu_pagevecs(get_cpu());
Andrew Morton80bfed92006-01-06 00:11:14 -0800256 put_cpu();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257}
258
Nick Piggin053837f2006-01-18 17:42:27 -0800259#ifdef CONFIG_NUMA
David Howellsc4028952006-11-22 14:57:56 +0000260static void lru_add_drain_per_cpu(struct work_struct *dummy)
Nick Piggin053837f2006-01-18 17:42:27 -0800261{
262 lru_add_drain();
263}
264
265/*
266 * Returns 0 for success
267 */
268int lru_add_drain_all(void)
269{
David Howellsc4028952006-11-22 14:57:56 +0000270 return schedule_on_each_cpu(lru_add_drain_per_cpu);
Nick Piggin053837f2006-01-18 17:42:27 -0800271}
272
273#else
274
275/*
276 * Returns 0 for success
277 */
278int lru_add_drain_all(void)
279{
280 lru_add_drain();
281 return 0;
282}
283#endif
284
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 * Batched page_cache_release(). Decrement the reference count on all the
287 * passed pages. If it fell to zero then remove the page from the LRU and
288 * free it.
289 *
290 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
291 * for the remainder of the operation.
292 *
293 * The locking in this function is against shrink_cache(): we recheck the
294 * page count inside the lock to see whether shrink_cache grabbed the page
295 * via the LRU. If it did, give up: shrink_cache will free it.
296 */
297void release_pages(struct page **pages, int nr, int cold)
298{
299 int i;
300 struct pagevec pages_to_free;
301 struct zone *zone = NULL;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700302 unsigned long uninitialized_var(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303
304 pagevec_init(&pages_to_free, cold);
305 for (i = 0; i < nr; i++) {
306 struct page *page = pages[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307
Nick Piggin8519fb32006-02-07 12:58:52 -0800308 if (unlikely(PageCompound(page))) {
309 if (zone) {
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700310 spin_unlock_irqrestore(&zone->lru_lock, flags);
Nick Piggin8519fb32006-02-07 12:58:52 -0800311 zone = NULL;
312 }
313 put_compound_page(page);
314 continue;
315 }
316
Nick Pigginb5810032005-10-29 18:16:12 -0700317 if (!put_page_testzero(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 continue;
319
Nick Piggin46453a62006-03-22 00:07:58 -0800320 if (PageLRU(page)) {
321 struct zone *pagezone = page_zone(page);
322 if (pagezone != zone) {
323 if (zone)
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700324 spin_unlock_irqrestore(&zone->lru_lock,
325 flags);
Nick Piggin46453a62006-03-22 00:07:58 -0800326 zone = pagezone;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700327 spin_lock_irqsave(&zone->lru_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 }
Nick Piggin725d7042006-09-25 23:30:55 -0700329 VM_BUG_ON(!PageLRU(page));
Nick Piggin67453912006-03-22 00:08:00 -0800330 __ClearPageLRU(page);
Nick Piggin46453a62006-03-22 00:07:58 -0800331 del_page_from_lru(zone, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 }
Nick Piggin46453a62006-03-22 00:07:58 -0800333
334 if (!pagevec_add(&pages_to_free, page)) {
335 if (zone) {
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700336 spin_unlock_irqrestore(&zone->lru_lock, flags);
Nick Piggin46453a62006-03-22 00:07:58 -0800337 zone = NULL;
338 }
339 __pagevec_free(&pages_to_free);
340 pagevec_reinit(&pages_to_free);
341 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 }
343 if (zone)
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700344 spin_unlock_irqrestore(&zone->lru_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345
346 pagevec_free(&pages_to_free);
347}
348
349/*
350 * The pages which we're about to release may be in the deferred lru-addition
351 * queues. That would prevent them from really being freed right now. That's
352 * OK from a correctness point of view but is inefficient - those pages may be
353 * cache-warm and we want to give them back to the page allocator ASAP.
354 *
355 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
356 * and __pagevec_lru_add_active() call release_pages() directly to avoid
357 * mutual recursion.
358 */
359void __pagevec_release(struct pagevec *pvec)
360{
361 lru_add_drain();
362 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
363 pagevec_reinit(pvec);
364}
365
Steve French7f285702005-11-01 10:22:55 -0800366EXPORT_SYMBOL(__pagevec_release);
367
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368/*
369 * pagevec_release() for pages which are known to not be on the LRU
370 *
371 * This function reinitialises the caller's pagevec.
372 */
373void __pagevec_release_nonlru(struct pagevec *pvec)
374{
375 int i;
376 struct pagevec pages_to_free;
377
378 pagevec_init(&pages_to_free, pvec->cold);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 for (i = 0; i < pagevec_count(pvec); i++) {
380 struct page *page = pvec->pages[i];
381
Nick Piggin725d7042006-09-25 23:30:55 -0700382 VM_BUG_ON(PageLRU(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 if (put_page_testzero(page))
384 pagevec_add(&pages_to_free, page);
385 }
386 pagevec_free(&pages_to_free);
387 pagevec_reinit(pvec);
388}
389
390/*
391 * Add the passed pages to the LRU, then drop the caller's refcount
392 * on them. Reinitialises the caller's pagevec.
393 */
394void __pagevec_lru_add(struct pagevec *pvec)
395{
396 int i;
397 struct zone *zone = NULL;
398
399 for (i = 0; i < pagevec_count(pvec); i++) {
400 struct page *page = pvec->pages[i];
401 struct zone *pagezone = page_zone(page);
402
403 if (pagezone != zone) {
404 if (zone)
405 spin_unlock_irq(&zone->lru_lock);
406 zone = pagezone;
407 spin_lock_irq(&zone->lru_lock);
408 }
Nick Piggin725d7042006-09-25 23:30:55 -0700409 VM_BUG_ON(PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -0800410 SetPageLRU(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 add_page_to_inactive_list(zone, page);
412 }
413 if (zone)
414 spin_unlock_irq(&zone->lru_lock);
415 release_pages(pvec->pages, pvec->nr, pvec->cold);
416 pagevec_reinit(pvec);
417}
418
419EXPORT_SYMBOL(__pagevec_lru_add);
420
421void __pagevec_lru_add_active(struct pagevec *pvec)
422{
423 int i;
424 struct zone *zone = NULL;
425
426 for (i = 0; i < pagevec_count(pvec); i++) {
427 struct page *page = pvec->pages[i];
428 struct zone *pagezone = page_zone(page);
429
430 if (pagezone != zone) {
431 if (zone)
432 spin_unlock_irq(&zone->lru_lock);
433 zone = pagezone;
434 spin_lock_irq(&zone->lru_lock);
435 }
Nick Piggin725d7042006-09-25 23:30:55 -0700436 VM_BUG_ON(PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -0800437 SetPageLRU(page);
Nick Piggin725d7042006-09-25 23:30:55 -0700438 VM_BUG_ON(PageActive(page));
Nick Piggin4c84cac2006-03-22 00:08:00 -0800439 SetPageActive(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 add_page_to_active_list(zone, page);
441 }
442 if (zone)
443 spin_unlock_irq(&zone->lru_lock);
444 release_pages(pvec->pages, pvec->nr, pvec->cold);
445 pagevec_reinit(pvec);
446}
447
448/*
449 * Try to drop buffers from the pages in a pagevec
450 */
451void pagevec_strip(struct pagevec *pvec)
452{
453 int i;
454
455 for (i = 0; i < pagevec_count(pvec); i++) {
456 struct page *page = pvec->pages[i];
457
458 if (PagePrivate(page) && !TestSetPageLocked(page)) {
Christoph Lameter5b40dc72006-03-16 23:04:07 -0800459 if (PagePrivate(page))
460 try_to_release_page(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461 unlock_page(page);
462 }
463 }
464}
465
466/**
467 * pagevec_lookup - gang pagecache lookup
468 * @pvec: Where the resulting pages are placed
469 * @mapping: The address_space to search
470 * @start: The starting page index
471 * @nr_pages: The maximum number of pages
472 *
473 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
474 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
475 * reference against the pages in @pvec.
476 *
477 * The search returns a group of mapping-contiguous pages with ascending
478 * indexes. There may be holes in the indices due to not-present pages.
479 *
480 * pagevec_lookup() returns the number of pages which were found.
481 */
482unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
483 pgoff_t start, unsigned nr_pages)
484{
485 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
486 return pagevec_count(pvec);
487}
488
Christoph Hellwig78539fd2006-01-11 20:47:41 +1100489EXPORT_SYMBOL(pagevec_lookup);
490
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
492 pgoff_t *index, int tag, unsigned nr_pages)
493{
494 pvec->nr = find_get_pages_tag(mapping, index, tag,
495 nr_pages, pvec->pages);
496 return pagevec_count(pvec);
497}
498
Steve French7f285702005-11-01 10:22:55 -0800499EXPORT_SYMBOL(pagevec_lookup_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500
501#ifdef CONFIG_SMP
502/*
503 * We tolerate a little inaccuracy to avoid ping-ponging the counter between
504 * CPUs
505 */
506#define ACCT_THRESHOLD max(16, NR_CPUS * 2)
507
508static DEFINE_PER_CPU(long, committed_space) = 0;
509
510void vm_acct_memory(long pages)
511{
512 long *local;
513
514 preempt_disable();
515 local = &__get_cpu_var(committed_space);
516 *local += pages;
517 if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) {
518 atomic_add(*local, &vm_committed_space);
519 *local = 0;
520 }
521 preempt_enable();
522}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523
524#ifdef CONFIG_HOTPLUG_CPU
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525
526/* Drop the CPU's cached committed space back into the central pool. */
527static int cpu_swap_callback(struct notifier_block *nfb,
528 unsigned long action,
529 void *hcpu)
530{
531 long *committed;
532
533 committed = &per_cpu(committed_space, (long)hcpu);
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -0700534 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 atomic_add(*committed, &vm_committed_space);
536 *committed = 0;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700537 drain_cpu_pagevecs((long)hcpu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538 }
539 return NOTIFY_OK;
540}
541#endif /* CONFIG_HOTPLUG_CPU */
542#endif /* CONFIG_SMP */
543
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544/*
545 * Perform any setup for the swap system
546 */
547void __init swap_setup(void)
548{
549 unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
550
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700551#ifdef CONFIG_SWAP
552 bdi_init(swapper_space.backing_dev_info);
553#endif
554
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555 /* Use a smaller cluster for small-memory machines */
556 if (megs < 16)
557 page_cluster = 2;
558 else
559 page_cluster = 3;
560 /*
561 * Right now other parts of the system means that we
562 * _really_ don't want to cluster much more
563 */
Ingo Molnar02316062006-12-06 20:38:17 -0800564#ifdef CONFIG_HOTPLUG_CPU
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565 hotcpu_notifier(cpu_swap_callback, 0);
Ingo Molnar02316062006-12-06 20:38:17 -0800566#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567}