blob: 021a2960ef9e18d061c972590f7651a35e7652ce [file] [log] [blame]
Mel Gorman748446b2010-05-24 14:32:27 -07001/*
2 * linux/mm/compaction.c
3 *
4 * Memory compaction for the reduction of external fragmentation. Note that
5 * this heavily depends upon page migration to do all the real heavy
6 * lifting
7 *
8 * Copyright IBM Corp. 2007-2010 Mel Gorman <mel@csn.ul.ie>
9 */
10#include <linux/swap.h>
11#include <linux/migrate.h>
12#include <linux/compaction.h>
13#include <linux/mm_inline.h>
14#include <linux/backing-dev.h>
Mel Gorman76ab0f52010-05-24 14:32:28 -070015#include <linux/sysctl.h>
Mel Gormaned4a6d72010-05-24 14:32:29 -070016#include <linux/sysfs.h>
Mel Gorman748446b2010-05-24 14:32:27 -070017#include "internal.h"
18
Mel Gormanb7aba692011-01-13 15:45:54 -080019#define CREATE_TRACE_POINTS
20#include <trace/events/compaction.h>
21
Mel Gorman748446b2010-05-24 14:32:27 -070022/*
23 * compact_control is used to track pages being migrated and the free pages
24 * they are being migrated to during memory compaction. The free_pfn starts
25 * at the end of a zone and migrate_pfn begins at the start. Movable pages
26 * are moved to the end of a zone during a compaction run and the run
27 * completes when free_pfn <= migrate_pfn
28 */
29struct compact_control {
30 struct list_head freepages; /* List of free pages to migrate to */
31 struct list_head migratepages; /* List of pages being migrated */
32 unsigned long nr_freepages; /* Number of isolated free pages */
33 unsigned long nr_migratepages; /* Number of pages to migrate */
34 unsigned long free_pfn; /* isolate_freepages search base */
35 unsigned long migrate_pfn; /* isolate_migratepages search base */
Mel Gorman77f1fe62011-01-13 15:45:57 -080036 bool sync; /* Synchronous migration */
Mel Gorman748446b2010-05-24 14:32:27 -070037
38 /* Account for isolated anon and file pages */
39 unsigned long nr_anon;
40 unsigned long nr_file;
41
Mel Gorman56de7262010-05-24 14:32:30 -070042 unsigned int order; /* order a direct compactor needs */
43 int migratetype; /* MOVABLE, RECLAIMABLE etc */
Mel Gorman748446b2010-05-24 14:32:27 -070044 struct zone *zone;
45};
46
47static unsigned long release_freepages(struct list_head *freelist)
48{
49 struct page *page, *next;
50 unsigned long count = 0;
51
52 list_for_each_entry_safe(page, next, freelist, lru) {
53 list_del(&page->lru);
54 __free_page(page);
55 count++;
56 }
57
58 return count;
59}
60
61/* Isolate free pages onto a private freelist. Must hold zone->lock */
62static unsigned long isolate_freepages_block(struct zone *zone,
63 unsigned long blockpfn,
64 struct list_head *freelist)
65{
66 unsigned long zone_end_pfn, end_pfn;
Mel Gormanb7aba692011-01-13 15:45:54 -080067 int nr_scanned = 0, total_isolated = 0;
Mel Gorman748446b2010-05-24 14:32:27 -070068 struct page *cursor;
69
70 /* Get the last PFN we should scan for free pages at */
71 zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
72 end_pfn = min(blockpfn + pageblock_nr_pages, zone_end_pfn);
73
74 /* Find the first usable PFN in the block to initialse page cursor */
75 for (; blockpfn < end_pfn; blockpfn++) {
76 if (pfn_valid_within(blockpfn))
77 break;
78 }
79 cursor = pfn_to_page(blockpfn);
80
81 /* Isolate free pages. This assumes the block is valid */
82 for (; blockpfn < end_pfn; blockpfn++, cursor++) {
83 int isolated, i;
84 struct page *page = cursor;
85
86 if (!pfn_valid_within(blockpfn))
87 continue;
Mel Gormanb7aba692011-01-13 15:45:54 -080088 nr_scanned++;
Mel Gorman748446b2010-05-24 14:32:27 -070089
90 if (!PageBuddy(page))
91 continue;
92
93 /* Found a free page, break it into order-0 pages */
94 isolated = split_free_page(page);
95 total_isolated += isolated;
96 for (i = 0; i < isolated; i++) {
97 list_add(&page->lru, freelist);
98 page++;
99 }
100
101 /* If a page was split, advance to the end of it */
102 if (isolated) {
103 blockpfn += isolated - 1;
104 cursor += isolated - 1;
105 }
106 }
107
Mel Gormanb7aba692011-01-13 15:45:54 -0800108 trace_mm_compaction_isolate_freepages(nr_scanned, total_isolated);
Mel Gorman748446b2010-05-24 14:32:27 -0700109 return total_isolated;
110}
111
112/* Returns true if the page is within a block suitable for migration to */
113static bool suitable_migration_target(struct page *page)
114{
115
116 int migratetype = get_pageblock_migratetype(page);
117
118 /* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
119 if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE)
120 return false;
121
122 /* If the page is a large free page, then allow migration */
123 if (PageBuddy(page) && page_order(page) >= pageblock_order)
124 return true;
125
126 /* If the block is MIGRATE_MOVABLE, allow migration */
127 if (migratetype == MIGRATE_MOVABLE)
128 return true;
129
130 /* Otherwise skip the block */
131 return false;
132}
133
134/*
135 * Based on information in the current compact_control, find blocks
136 * suitable for isolating free pages from and then isolate them.
137 */
138static void isolate_freepages(struct zone *zone,
139 struct compact_control *cc)
140{
141 struct page *page;
142 unsigned long high_pfn, low_pfn, pfn;
143 unsigned long flags;
144 int nr_freepages = cc->nr_freepages;
145 struct list_head *freelist = &cc->freepages;
146
147 pfn = cc->free_pfn;
148 low_pfn = cc->migrate_pfn + pageblock_nr_pages;
149 high_pfn = low_pfn;
150
151 /*
152 * Isolate free pages until enough are available to migrate the
153 * pages on cc->migratepages. We stop searching if the migrate
154 * and free page scanners meet or enough free pages are isolated.
155 */
Mel Gorman748446b2010-05-24 14:32:27 -0700156 for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages;
157 pfn -= pageblock_nr_pages) {
158 unsigned long isolated;
159
160 if (!pfn_valid(pfn))
161 continue;
162
163 /*
164 * Check for overlapping nodes/zones. It's possible on some
165 * configurations to have a setup like
166 * node0 node1 node0
167 * i.e. it's possible that all pages within a zones range of
168 * pages do not belong to a single zone.
169 */
170 page = pfn_to_page(pfn);
171 if (page_zone(page) != zone)
172 continue;
173
174 /* Check the block is suitable for migration */
175 if (!suitable_migration_target(page))
176 continue;
177
Mel Gorman602605a2011-03-22 16:33:08 -0700178 /*
179 * Found a block suitable for isolating free pages from. Now
180 * we disabled interrupts, double check things are ok and
181 * isolate the pages. This is to minimise the time IRQs
182 * are disabled
183 */
184 isolated = 0;
185 spin_lock_irqsave(&zone->lock, flags);
186 if (suitable_migration_target(page)) {
187 isolated = isolate_freepages_block(zone, pfn, freelist);
188 nr_freepages += isolated;
189 }
190 spin_unlock_irqrestore(&zone->lock, flags);
Mel Gorman748446b2010-05-24 14:32:27 -0700191
192 /*
193 * Record the highest PFN we isolated pages from. When next
194 * looking for free pages, the search will restart here as
195 * page migration may have returned some pages to the allocator
196 */
197 if (isolated)
198 high_pfn = max(high_pfn, pfn);
199 }
Mel Gorman748446b2010-05-24 14:32:27 -0700200
201 /* split_free_page does not map the pages */
202 list_for_each_entry(page, freelist, lru) {
203 arch_alloc_page(page, 0);
204 kernel_map_pages(page, 1, 1);
205 }
206
207 cc->free_pfn = high_pfn;
208 cc->nr_freepages = nr_freepages;
209}
210
211/* Update the number of anon and file isolated pages in the zone */
212static void acct_isolated(struct zone *zone, struct compact_control *cc)
213{
214 struct page *page;
215 unsigned int count[NR_LRU_LISTS] = { 0, };
216
217 list_for_each_entry(page, &cc->migratepages, lru) {
218 int lru = page_lru_base_type(page);
219 count[lru]++;
220 }
221
222 cc->nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
223 cc->nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
224 __mod_zone_page_state(zone, NR_ISOLATED_ANON, cc->nr_anon);
225 __mod_zone_page_state(zone, NR_ISOLATED_FILE, cc->nr_file);
226}
227
228/* Similar to reclaim, but different enough that they don't share logic */
229static bool too_many_isolated(struct zone *zone)
230{
Minchan Kimbc693042010-09-09 16:38:00 -0700231 unsigned long active, inactive, isolated;
Mel Gorman748446b2010-05-24 14:32:27 -0700232
233 inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
234 zone_page_state(zone, NR_INACTIVE_ANON);
Minchan Kimbc693042010-09-09 16:38:00 -0700235 active = zone_page_state(zone, NR_ACTIVE_FILE) +
236 zone_page_state(zone, NR_ACTIVE_ANON);
Mel Gorman748446b2010-05-24 14:32:27 -0700237 isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
238 zone_page_state(zone, NR_ISOLATED_ANON);
239
Minchan Kimbc693042010-09-09 16:38:00 -0700240 return isolated > (inactive + active) / 2;
Mel Gorman748446b2010-05-24 14:32:27 -0700241}
242
243/*
244 * Isolate all pages that can be migrated from the block pointed to by
245 * the migrate scanner within compact_control.
246 */
247static unsigned long isolate_migratepages(struct zone *zone,
248 struct compact_control *cc)
249{
250 unsigned long low_pfn, end_pfn;
Mel Gorman9927af742011-01-13 15:45:59 -0800251 unsigned long last_pageblock_nr = 0, pageblock_nr;
Mel Gormanb7aba692011-01-13 15:45:54 -0800252 unsigned long nr_scanned = 0, nr_isolated = 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700253 struct list_head *migratelist = &cc->migratepages;
254
255 /* Do not scan outside zone boundaries */
256 low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
257
258 /* Only scan within a pageblock boundary */
259 end_pfn = ALIGN(low_pfn + pageblock_nr_pages, pageblock_nr_pages);
260
261 /* Do not cross the free scanner or scan within a memory hole */
262 if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) {
263 cc->migrate_pfn = end_pfn;
264 return 0;
265 }
266
267 /*
268 * Ensure that there are not too many pages isolated from the LRU
269 * list by either parallel reclaimers or compaction. If there are,
270 * delay for some time until fewer pages are isolated
271 */
272 while (unlikely(too_many_isolated(zone))) {
273 congestion_wait(BLK_RW_ASYNC, HZ/10);
274
275 if (fatal_signal_pending(current))
276 return 0;
277 }
278
279 /* Time to isolate some pages for migration */
Andrea Arcangelib2eef8c2011-03-22 16:33:10 -0700280 cond_resched();
Mel Gorman748446b2010-05-24 14:32:27 -0700281 spin_lock_irq(&zone->lru_lock);
282 for (; low_pfn < end_pfn; low_pfn++) {
283 struct page *page;
Andrea Arcangelib2eef8c2011-03-22 16:33:10 -0700284 bool locked = true;
285
286 /* give a chance to irqs before checking need_resched() */
287 if (!((low_pfn+1) % SWAP_CLUSTER_MAX)) {
288 spin_unlock_irq(&zone->lru_lock);
289 locked = false;
290 }
291 if (need_resched() || spin_is_contended(&zone->lru_lock)) {
292 if (locked)
293 spin_unlock_irq(&zone->lru_lock);
294 cond_resched();
295 spin_lock_irq(&zone->lru_lock);
296 if (fatal_signal_pending(current))
297 break;
298 } else if (!locked)
299 spin_lock_irq(&zone->lru_lock);
300
Mel Gorman748446b2010-05-24 14:32:27 -0700301 if (!pfn_valid_within(low_pfn))
302 continue;
Mel Gormanb7aba692011-01-13 15:45:54 -0800303 nr_scanned++;
Mel Gorman748446b2010-05-24 14:32:27 -0700304
305 /* Get the page and skip if free */
306 page = pfn_to_page(low_pfn);
307 if (PageBuddy(page))
308 continue;
309
Mel Gorman9927af742011-01-13 15:45:59 -0800310 /*
311 * For async migration, also only scan in MOVABLE blocks. Async
312 * migration is optimistic to see if the minimum amount of work
313 * satisfies the allocation
314 */
315 pageblock_nr = low_pfn >> pageblock_order;
316 if (!cc->sync && last_pageblock_nr != pageblock_nr &&
317 get_pageblock_migratetype(page) != MIGRATE_MOVABLE) {
318 low_pfn += pageblock_nr_pages;
319 low_pfn = ALIGN(low_pfn, pageblock_nr_pages) - 1;
320 last_pageblock_nr = pageblock_nr;
321 continue;
322 }
323
Andrea Arcangelibc835012011-01-13 15:47:08 -0800324 if (!PageLRU(page))
325 continue;
326
327 /*
328 * PageLRU is set, and lru_lock excludes isolation,
329 * splitting and collapsing (collapsing has already
330 * happened if PageLRU is set).
331 */
332 if (PageTransHuge(page)) {
333 low_pfn += (1 << compound_order(page)) - 1;
334 continue;
335 }
336
Mel Gorman748446b2010-05-24 14:32:27 -0700337 /* Try isolate the page */
338 if (__isolate_lru_page(page, ISOLATE_BOTH, 0) != 0)
339 continue;
340
Andrea Arcangelibc835012011-01-13 15:47:08 -0800341 VM_BUG_ON(PageTransCompound(page));
342
Mel Gorman748446b2010-05-24 14:32:27 -0700343 /* Successfully isolated */
344 del_page_from_lru_list(zone, page, page_lru(page));
345 list_add(&page->lru, migratelist);
Mel Gorman748446b2010-05-24 14:32:27 -0700346 cc->nr_migratepages++;
Mel Gormanb7aba692011-01-13 15:45:54 -0800347 nr_isolated++;
Mel Gorman748446b2010-05-24 14:32:27 -0700348
349 /* Avoid isolating too much */
350 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
351 break;
352 }
353
354 acct_isolated(zone, cc);
355
356 spin_unlock_irq(&zone->lru_lock);
357 cc->migrate_pfn = low_pfn;
358
Mel Gormanb7aba692011-01-13 15:45:54 -0800359 trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated);
360
Mel Gorman748446b2010-05-24 14:32:27 -0700361 return cc->nr_migratepages;
362}
363
364/*
365 * This is a migrate-callback that "allocates" freepages by taking pages
366 * from the isolated freelists in the block we are migrating to.
367 */
368static struct page *compaction_alloc(struct page *migratepage,
369 unsigned long data,
370 int **result)
371{
372 struct compact_control *cc = (struct compact_control *)data;
373 struct page *freepage;
374
375 /* Isolate free pages if necessary */
376 if (list_empty(&cc->freepages)) {
377 isolate_freepages(cc->zone, cc);
378
379 if (list_empty(&cc->freepages))
380 return NULL;
381 }
382
383 freepage = list_entry(cc->freepages.next, struct page, lru);
384 list_del(&freepage->lru);
385 cc->nr_freepages--;
386
387 return freepage;
388}
389
390/*
391 * We cannot control nr_migratepages and nr_freepages fully when migration is
392 * running as migrate_pages() has no knowledge of compact_control. When
393 * migration is complete, we count the number of pages on the lists by hand.
394 */
395static void update_nr_listpages(struct compact_control *cc)
396{
397 int nr_migratepages = 0;
398 int nr_freepages = 0;
399 struct page *page;
400
401 list_for_each_entry(page, &cc->migratepages, lru)
402 nr_migratepages++;
403 list_for_each_entry(page, &cc->freepages, lru)
404 nr_freepages++;
405
406 cc->nr_migratepages = nr_migratepages;
407 cc->nr_freepages = nr_freepages;
408}
409
410static int compact_finished(struct zone *zone,
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800411 struct compact_control *cc)
Mel Gorman748446b2010-05-24 14:32:27 -0700412{
Mel Gorman56de7262010-05-24 14:32:30 -0700413 unsigned int order;
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800414 unsigned long watermark;
Mel Gorman56de7262010-05-24 14:32:30 -0700415
Mel Gorman748446b2010-05-24 14:32:27 -0700416 if (fatal_signal_pending(current))
417 return COMPACT_PARTIAL;
418
419 /* Compaction run completes if the migrate and free scanner meet */
420 if (cc->free_pfn <= cc->migrate_pfn)
421 return COMPACT_COMPLETE;
422
Mel Gorman56de7262010-05-24 14:32:30 -0700423 /* Compaction run is not finished if the watermark is not met */
Andrea Arcangelid527caf2011-03-22 16:30:38 -0700424 watermark = low_wmark_pages(zone);
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800425 watermark += (1 << cc->order);
426
Mel Gorman56de7262010-05-24 14:32:30 -0700427 if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
428 return COMPACT_CONTINUE;
429
Johannes Weiner82478fb2011-01-20 14:44:21 -0800430 /*
431 * order == -1 is expected when compacting via
432 * /proc/sys/vm/compact_memory
433 */
Mel Gorman56de7262010-05-24 14:32:30 -0700434 if (cc->order == -1)
435 return COMPACT_CONTINUE;
436
437 /* Direct compactor: Is a suitable page free? */
438 for (order = cc->order; order < MAX_ORDER; order++) {
439 /* Job done if page is free of the right migratetype */
440 if (!list_empty(&zone->free_area[order].free_list[cc->migratetype]))
441 return COMPACT_PARTIAL;
442
443 /* Job done if allocation would set block type */
444 if (order >= pageblock_order && zone->free_area[order].nr_free)
445 return COMPACT_PARTIAL;
446 }
447
Mel Gorman748446b2010-05-24 14:32:27 -0700448 return COMPACT_CONTINUE;
449}
450
Mel Gorman3e7d3442011-01-13 15:45:56 -0800451/*
452 * compaction_suitable: Is this suitable to run compaction on this zone now?
453 * Returns
454 * COMPACT_SKIPPED - If there are too few free pages for compaction
455 * COMPACT_PARTIAL - If the allocation would succeed without compaction
456 * COMPACT_CONTINUE - If compaction should run now
457 */
458unsigned long compaction_suitable(struct zone *zone, int order)
459{
460 int fragindex;
461 unsigned long watermark;
462
463 /*
464 * Watermarks for order-0 must be met for compaction. Note the 2UL.
465 * This is because during migration, copies of pages need to be
466 * allocated and for a short time, the footprint is higher
467 */
468 watermark = low_wmark_pages(zone) + (2UL << order);
469 if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
470 return COMPACT_SKIPPED;
471
472 /*
Johannes Weiner82478fb2011-01-20 14:44:21 -0800473 * order == -1 is expected when compacting via
474 * /proc/sys/vm/compact_memory
475 */
476 if (order == -1)
477 return COMPACT_CONTINUE;
478
479 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -0800480 * fragmentation index determines if allocation failures are due to
481 * low memory or external fragmentation
482 *
483 * index of -1 implies allocations might succeed dependingon watermarks
484 * index towards 0 implies failure is due to lack of memory
485 * index towards 1000 implies failure is due to fragmentation
486 *
487 * Only compact if a failure would be due to fragmentation.
488 */
489 fragindex = fragmentation_index(zone, order);
490 if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
491 return COMPACT_SKIPPED;
492
493 if (fragindex == -1 && zone_watermark_ok(zone, order, watermark, 0, 0))
494 return COMPACT_PARTIAL;
495
496 return COMPACT_CONTINUE;
497}
498
Mel Gorman748446b2010-05-24 14:32:27 -0700499static int compact_zone(struct zone *zone, struct compact_control *cc)
500{
501 int ret;
502
Mel Gorman3e7d3442011-01-13 15:45:56 -0800503 ret = compaction_suitable(zone, cc->order);
504 switch (ret) {
505 case COMPACT_PARTIAL:
506 case COMPACT_SKIPPED:
507 /* Compaction is likely to fail */
508 return ret;
509 case COMPACT_CONTINUE:
510 /* Fall through to compaction */
511 ;
512 }
513
Mel Gorman748446b2010-05-24 14:32:27 -0700514 /* Setup to move all movable pages to the end of the zone */
515 cc->migrate_pfn = zone->zone_start_pfn;
516 cc->free_pfn = cc->migrate_pfn + zone->spanned_pages;
517 cc->free_pfn &= ~(pageblock_nr_pages-1);
518
519 migrate_prep_local();
520
521 while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
522 unsigned long nr_migrate, nr_remaining;
Minchan Kim9d502c12011-03-22 16:30:39 -0700523 int err;
Mel Gorman748446b2010-05-24 14:32:27 -0700524
525 if (!isolate_migratepages(zone, cc))
526 continue;
527
528 nr_migrate = cc->nr_migratepages;
Minchan Kim9d502c12011-03-22 16:30:39 -0700529 err = migrate_pages(&cc->migratepages, compaction_alloc,
Mel Gorman7f0f2492011-01-13 15:45:58 -0800530 (unsigned long)cc, false,
Mel Gorman77f1fe62011-01-13 15:45:57 -0800531 cc->sync);
Mel Gorman748446b2010-05-24 14:32:27 -0700532 update_nr_listpages(cc);
533 nr_remaining = cc->nr_migratepages;
534
535 count_vm_event(COMPACTBLOCKS);
536 count_vm_events(COMPACTPAGES, nr_migrate - nr_remaining);
537 if (nr_remaining)
538 count_vm_events(COMPACTPAGEFAILED, nr_remaining);
Mel Gormanb7aba692011-01-13 15:45:54 -0800539 trace_mm_compaction_migratepages(nr_migrate - nr_remaining,
540 nr_remaining);
Mel Gorman748446b2010-05-24 14:32:27 -0700541
542 /* Release LRU pages not migrated */
Minchan Kim9d502c12011-03-22 16:30:39 -0700543 if (err) {
Mel Gorman748446b2010-05-24 14:32:27 -0700544 putback_lru_pages(&cc->migratepages);
545 cc->nr_migratepages = 0;
546 }
547
548 }
549
550 /* Release free pages and check accounting */
551 cc->nr_freepages -= release_freepages(&cc->freepages);
552 VM_BUG_ON(cc->nr_freepages != 0);
553
554 return ret;
555}
Mel Gorman76ab0f52010-05-24 14:32:28 -0700556
Mel Gorman3e7d3442011-01-13 15:45:56 -0800557unsigned long compact_zone_order(struct zone *zone,
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800558 int order, gfp_t gfp_mask,
Andrea Arcangelid527caf2011-03-22 16:30:38 -0700559 bool sync)
Mel Gorman56de7262010-05-24 14:32:30 -0700560{
561 struct compact_control cc = {
562 .nr_freepages = 0,
563 .nr_migratepages = 0,
564 .order = order,
565 .migratetype = allocflags_to_migratetype(gfp_mask),
566 .zone = zone,
Mel Gorman77f1fe62011-01-13 15:45:57 -0800567 .sync = sync,
Mel Gorman56de7262010-05-24 14:32:30 -0700568 };
569 INIT_LIST_HEAD(&cc.freepages);
570 INIT_LIST_HEAD(&cc.migratepages);
571
572 return compact_zone(zone, &cc);
573}
574
Mel Gorman5e771902010-05-24 14:32:31 -0700575int sysctl_extfrag_threshold = 500;
576
Mel Gorman56de7262010-05-24 14:32:30 -0700577/**
578 * try_to_compact_pages - Direct compact to satisfy a high-order allocation
579 * @zonelist: The zonelist used for the current allocation
580 * @order: The order of the current allocation
581 * @gfp_mask: The GFP mask of the current allocation
582 * @nodemask: The allowed nodes to allocate from
Mel Gorman77f1fe62011-01-13 15:45:57 -0800583 * @sync: Whether migration is synchronous or not
Mel Gorman56de7262010-05-24 14:32:30 -0700584 *
585 * This is the main entry point for direct page compaction.
586 */
587unsigned long try_to_compact_pages(struct zonelist *zonelist,
Mel Gorman77f1fe62011-01-13 15:45:57 -0800588 int order, gfp_t gfp_mask, nodemask_t *nodemask,
589 bool sync)
Mel Gorman56de7262010-05-24 14:32:30 -0700590{
591 enum zone_type high_zoneidx = gfp_zone(gfp_mask);
592 int may_enter_fs = gfp_mask & __GFP_FS;
593 int may_perform_io = gfp_mask & __GFP_IO;
Mel Gorman56de7262010-05-24 14:32:30 -0700594 struct zoneref *z;
595 struct zone *zone;
596 int rc = COMPACT_SKIPPED;
597
598 /*
599 * Check whether it is worth even starting compaction. The order check is
600 * made because an assumption is made that the page allocator can satisfy
601 * the "cheaper" orders without taking special steps
602 */
Andrea Arcangelic5a73c32011-01-13 15:47:11 -0800603 if (!order || !may_enter_fs || !may_perform_io)
Mel Gorman56de7262010-05-24 14:32:30 -0700604 return rc;
605
606 count_vm_event(COMPACTSTALL);
607
608 /* Compact each zone in the list */
609 for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
610 nodemask) {
Mel Gorman56de7262010-05-24 14:32:30 -0700611 int status;
612
Andrea Arcangelid527caf2011-03-22 16:30:38 -0700613 status = compact_zone_order(zone, order, gfp_mask, sync);
Mel Gorman56de7262010-05-24 14:32:30 -0700614 rc = max(status, rc);
615
Mel Gorman3e7d3442011-01-13 15:45:56 -0800616 /* If a normal allocation would succeed, stop compacting */
617 if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0))
Mel Gorman56de7262010-05-24 14:32:30 -0700618 break;
619 }
620
621 return rc;
622}
623
624
Mel Gorman76ab0f52010-05-24 14:32:28 -0700625/* Compact all zones within a node */
626static int compact_node(int nid)
627{
628 int zoneid;
629 pg_data_t *pgdat;
630 struct zone *zone;
631
632 if (nid < 0 || nid >= nr_node_ids || !node_online(nid))
633 return -EINVAL;
634 pgdat = NODE_DATA(nid);
635
636 /* Flush pending updates to the LRU lists */
637 lru_add_drain_all();
638
639 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
640 struct compact_control cc = {
641 .nr_freepages = 0,
642 .nr_migratepages = 0,
Mel Gorman56de7262010-05-24 14:32:30 -0700643 .order = -1,
Mel Gorman76ab0f52010-05-24 14:32:28 -0700644 };
645
646 zone = &pgdat->node_zones[zoneid];
647 if (!populated_zone(zone))
648 continue;
649
650 cc.zone = zone;
651 INIT_LIST_HEAD(&cc.freepages);
652 INIT_LIST_HEAD(&cc.migratepages);
653
654 compact_zone(zone, &cc);
655
656 VM_BUG_ON(!list_empty(&cc.freepages));
657 VM_BUG_ON(!list_empty(&cc.migratepages));
658 }
659
660 return 0;
661}
662
663/* Compact all nodes in the system */
664static int compact_nodes(void)
665{
666 int nid;
667
668 for_each_online_node(nid)
669 compact_node(nid);
670
671 return COMPACT_COMPLETE;
672}
673
674/* The written value is actually unused, all memory is compacted */
675int sysctl_compact_memory;
676
677/* This is the entry point for compacting all nodes via /proc/sys/vm */
678int sysctl_compaction_handler(struct ctl_table *table, int write,
679 void __user *buffer, size_t *length, loff_t *ppos)
680{
681 if (write)
682 return compact_nodes();
683
684 return 0;
685}
Mel Gormaned4a6d72010-05-24 14:32:29 -0700686
Mel Gorman5e771902010-05-24 14:32:31 -0700687int sysctl_extfrag_handler(struct ctl_table *table, int write,
688 void __user *buffer, size_t *length, loff_t *ppos)
689{
690 proc_dointvec_minmax(table, write, buffer, length, ppos);
691
692 return 0;
693}
694
Mel Gormaned4a6d72010-05-24 14:32:29 -0700695#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
696ssize_t sysfs_compact_node(struct sys_device *dev,
697 struct sysdev_attribute *attr,
698 const char *buf, size_t count)
699{
700 compact_node(dev->id);
701
702 return count;
703}
704static SYSDEV_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
705
706int compaction_register_node(struct node *node)
707{
708 return sysdev_create_file(&node->sysdev, &attr_compact);
709}
710
711void compaction_unregister_node(struct node *node)
712{
713 return sysdev_remove_file(&node->sysdev, &attr_compact);
714}
715#endif /* CONFIG_SYSFS && CONFIG_NUMA */