mm/vmstat.c: cleanups
[linux-2.6.git] / mm / vmstat.c
1 /*
2  *  linux/mm/vmstat.c
3  *
4  *  Manages VM statistics
5  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
6  *
7  *  zoned VM statistics
8  *  Copyright (C) 2006 Silicon Graphics, Inc.,
9  *              Christoph Lameter <christoph@lameter.com>
10  */
11
12 #include <linux/mm.h>
13 #include <linux/err.h>
14 #include <linux/module.h>
15 #include <linux/cpu.h>
16 #include <linux/sched.h>
17
18 #ifdef CONFIG_VM_EVENT_COUNTERS
19 DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
20 EXPORT_PER_CPU_SYMBOL(vm_event_states);
21
22 static void sum_vm_events(unsigned long *ret, cpumask_t *cpumask)
23 {
24         int cpu = 0;
25         int i;
26
27         memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
28
29         cpu = first_cpu(*cpumask);
30         while (cpu < NR_CPUS) {
31                 struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
32
33                 cpu = next_cpu(cpu, *cpumask);
34
35                 if (cpu < NR_CPUS)
36                         prefetch(&per_cpu(vm_event_states, cpu));
37
38
39                 for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
40                         ret[i] += this->event[i];
41         }
42 }
43
44 /*
45  * Accumulate the vm event counters across all CPUs.
46  * The result is unavoidably approximate - it can change
47  * during and after execution of this function.
48 */
49 void all_vm_events(unsigned long *ret)
50 {
51         sum_vm_events(ret, &cpu_online_map);
52 }
53 EXPORT_SYMBOL_GPL(all_vm_events);
54
55 #ifdef CONFIG_HOTPLUG
56 /*
57  * Fold the foreign cpu events into our own.
58  *
59  * This is adding to the events on one processor
60  * but keeps the global counts constant.
61  */
62 void vm_events_fold_cpu(int cpu)
63 {
64         struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
65         int i;
66
67         for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
68                 count_vm_events(i, fold_state->event[i]);
69                 fold_state->event[i] = 0;
70         }
71 }
72 #endif /* CONFIG_HOTPLUG */
73
74 #endif /* CONFIG_VM_EVENT_COUNTERS */
75
76 /*
77  * Manage combined zone based / global counters
78  *
79  * vm_stat contains the global counters
80  */
81 atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
82 EXPORT_SYMBOL(vm_stat);
83
84 #ifdef CONFIG_SMP
85
86 static int calculate_threshold(struct zone *zone)
87 {
88         int threshold;
89         int mem;        /* memory in 128 MB units */
90
91         /*
92          * The threshold scales with the number of processors and the amount
93          * of memory per zone. More memory means that we can defer updates for
94          * longer, more processors could lead to more contention.
95          * fls() is used to have a cheap way of logarithmic scaling.
96          *
97          * Some sample thresholds:
98          *
99          * Threshold    Processors      (fls)   Zonesize        fls(mem+1)
100          * ------------------------------------------------------------------
101          * 8            1               1       0.9-1 GB        4
102          * 16           2               2       0.9-1 GB        4
103          * 20           2               2       1-2 GB          5
104          * 24           2               2       2-4 GB          6
105          * 28           2               2       4-8 GB          7
106          * 32           2               2       8-16 GB         8
107          * 4            2               2       <128M           1
108          * 30           4               3       2-4 GB          5
109          * 48           4               3       8-16 GB         8
110          * 32           8               4       1-2 GB          4
111          * 32           8               4       0.9-1GB         4
112          * 10           16              5       <128M           1
113          * 40           16              5       900M            4
114          * 70           64              7       2-4 GB          5
115          * 84           64              7       4-8 GB          6
116          * 108          512             9       4-8 GB          6
117          * 125          1024            10      8-16 GB         8
118          * 125          1024            10      16-32 GB        9
119          */
120
121         mem = zone->present_pages >> (27 - PAGE_SHIFT);
122
123         threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
124
125         /*
126          * Maximum threshold is 125
127          */
128         threshold = min(125, threshold);
129
130         return threshold;
131 }
132
133 /*
134  * Refresh the thresholds for each zone.
135  */
136 static void refresh_zone_stat_thresholds(void)
137 {
138         struct zone *zone;
139         int cpu;
140         int threshold;
141
142         for_each_zone(zone) {
143
144                 if (!zone->present_pages)
145                         continue;
146
147                 threshold = calculate_threshold(zone);
148
149                 for_each_online_cpu(cpu)
150                         zone_pcp(zone, cpu)->stat_threshold = threshold;
151         }
152 }
153
154 /*
155  * For use when we know that interrupts are disabled.
156  */
157 void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
158                                 int delta)
159 {
160         struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
161         s8 *p = pcp->vm_stat_diff + item;
162         long x;
163
164         x = delta + *p;
165
166         if (unlikely(x > pcp->stat_threshold || x < -pcp->stat_threshold)) {
167                 zone_page_state_add(x, zone, item);
168                 x = 0;
169         }
170         *p = x;
171 }
172 EXPORT_SYMBOL(__mod_zone_page_state);
173
174 /*
175  * For an unknown interrupt state
176  */
177 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
178                                         int delta)
179 {
180         unsigned long flags;
181
182         local_irq_save(flags);
183         __mod_zone_page_state(zone, item, delta);
184         local_irq_restore(flags);
185 }
186 EXPORT_SYMBOL(mod_zone_page_state);
187
188 /*
189  * Optimized increment and decrement functions.
190  *
191  * These are only for a single page and therefore can take a struct page *
192  * argument instead of struct zone *. This allows the inclusion of the code
193  * generated for page_zone(page) into the optimized functions.
194  *
195  * No overflow check is necessary and therefore the differential can be
196  * incremented or decremented in place which may allow the compilers to
197  * generate better code.
198  * The increment or decrement is known and therefore one boundary check can
199  * be omitted.
200  *
201  * NOTE: These functions are very performance sensitive. Change only
202  * with care.
203  *
204  * Some processors have inc/dec instructions that are atomic vs an interrupt.
205  * However, the code must first determine the differential location in a zone
206  * based on the processor number and then inc/dec the counter. There is no
207  * guarantee without disabling preemption that the processor will not change
208  * in between and therefore the atomicity vs. interrupt cannot be exploited
209  * in a useful way here.
210  */
211 void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
212 {
213         struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
214         s8 *p = pcp->vm_stat_diff + item;
215
216         (*p)++;
217
218         if (unlikely(*p > pcp->stat_threshold)) {
219                 int overstep = pcp->stat_threshold / 2;
220
221                 zone_page_state_add(*p + overstep, zone, item);
222                 *p = -overstep;
223         }
224 }
225
226 void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
227 {
228         __inc_zone_state(page_zone(page), item);
229 }
230 EXPORT_SYMBOL(__inc_zone_page_state);
231
232 void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
233 {
234         struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
235         s8 *p = pcp->vm_stat_diff + item;
236
237         (*p)--;
238
239         if (unlikely(*p < - pcp->stat_threshold)) {
240                 int overstep = pcp->stat_threshold / 2;
241
242                 zone_page_state_add(*p - overstep, zone, item);
243                 *p = overstep;
244         }
245 }
246
247 void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
248 {
249         __dec_zone_state(page_zone(page), item);
250 }
251 EXPORT_SYMBOL(__dec_zone_page_state);
252
253 void inc_zone_state(struct zone *zone, enum zone_stat_item item)
254 {
255         unsigned long flags;
256
257         local_irq_save(flags);
258         __inc_zone_state(zone, item);
259         local_irq_restore(flags);
260 }
261
262 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
263 {
264         unsigned long flags;
265         struct zone *zone;
266
267         zone = page_zone(page);
268         local_irq_save(flags);
269         __inc_zone_state(zone, item);
270         local_irq_restore(flags);
271 }
272 EXPORT_SYMBOL(inc_zone_page_state);
273
274 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
275 {
276         unsigned long flags;
277
278         local_irq_save(flags);
279         __dec_zone_page_state(page, item);
280         local_irq_restore(flags);
281 }
282 EXPORT_SYMBOL(dec_zone_page_state);
283
284 /*
285  * Update the zone counters for one cpu.
286  *
287  * Note that refresh_cpu_vm_stats strives to only access
288  * node local memory. The per cpu pagesets on remote zones are placed
289  * in the memory local to the processor using that pageset. So the
290  * loop over all zones will access a series of cachelines local to
291  * the processor.
292  *
293  * The call to zone_page_state_add updates the cachelines with the
294  * statistics in the remote zone struct as well as the global cachelines
295  * with the global counters. These could cause remote node cache line
296  * bouncing and will have to be only done when necessary.
297  */
298 void refresh_cpu_vm_stats(int cpu)
299 {
300         struct zone *zone;
301         int i;
302         unsigned long flags;
303
304         for_each_zone(zone) {
305                 struct per_cpu_pageset *p;
306
307                 if (!populated_zone(zone))
308                         continue;
309
310                 p = zone_pcp(zone, cpu);
311
312                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
313                         if (p->vm_stat_diff[i]) {
314                                 local_irq_save(flags);
315                                 zone_page_state_add(p->vm_stat_diff[i],
316                                         zone, i);
317                                 p->vm_stat_diff[i] = 0;
318 #ifdef CONFIG_NUMA
319                                 /* 3 seconds idle till flush */
320                                 p->expire = 3;
321 #endif
322                                 local_irq_restore(flags);
323                         }
324 #ifdef CONFIG_NUMA
325                 /*
326                  * Deal with draining the remote pageset of this
327                  * processor
328                  *
329                  * Check if there are pages remaining in this pageset
330                  * if not then there is nothing to expire.
331                  */
332                 if (!p->expire || (!p->pcp[0].count && !p->pcp[1].count))
333                         continue;
334
335                 /*
336                  * We never drain zones local to this processor.
337                  */
338                 if (zone_to_nid(zone) == numa_node_id()) {
339                         p->expire = 0;
340                         continue;
341                 }
342
343                 p->expire--;
344                 if (p->expire)
345                         continue;
346
347                 if (p->pcp[0].count)
348                         drain_zone_pages(zone, p->pcp + 0);
349
350                 if (p->pcp[1].count)
351                         drain_zone_pages(zone, p->pcp + 1);
352 #endif
353         }
354 }
355
356 #endif
357
358 #ifdef CONFIG_NUMA
359 /*
360  * zonelist = the list of zones passed to the allocator
361  * z        = the zone from which the allocation occurred.
362  *
363  * Must be called with interrupts disabled.
364  */
365 void zone_statistics(struct zonelist *zonelist, struct zone *z)
366 {
367         if (z->zone_pgdat == zonelist->zones[0]->zone_pgdat) {
368                 __inc_zone_state(z, NUMA_HIT);
369         } else {
370                 __inc_zone_state(z, NUMA_MISS);
371                 __inc_zone_state(zonelist->zones[0], NUMA_FOREIGN);
372         }
373         if (z->node == numa_node_id())
374                 __inc_zone_state(z, NUMA_LOCAL);
375         else
376                 __inc_zone_state(z, NUMA_OTHER);
377 }
378 #endif
379
380 #ifdef CONFIG_PROC_FS
381
382 #include <linux/seq_file.h>
383
384 static char * const migratetype_names[MIGRATE_TYPES] = {
385         "Unmovable",
386         "Reclaimable",
387         "Movable",
388         "Reserve",
389 };
390
391 static void *frag_start(struct seq_file *m, loff_t *pos)
392 {
393         pg_data_t *pgdat;
394         loff_t node = *pos;
395         for (pgdat = first_online_pgdat();
396              pgdat && node;
397              pgdat = next_online_pgdat(pgdat))
398                 --node;
399
400         return pgdat;
401 }
402
403 static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
404 {
405         pg_data_t *pgdat = (pg_data_t *)arg;
406
407         (*pos)++;
408         return next_online_pgdat(pgdat);
409 }
410
411 static void frag_stop(struct seq_file *m, void *arg)
412 {
413 }
414
415 /* Walk all the zones in a node and print using a callback */
416 static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
417                 void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
418 {
419         struct zone *zone;
420         struct zone *node_zones = pgdat->node_zones;
421         unsigned long flags;
422
423         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
424                 if (!populated_zone(zone))
425                         continue;
426
427                 spin_lock_irqsave(&zone->lock, flags);
428                 print(m, pgdat, zone);
429                 spin_unlock_irqrestore(&zone->lock, flags);
430         }
431 }
432
433 static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
434                                                 struct zone *zone)
435 {
436         int order;
437
438         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
439         for (order = 0; order < MAX_ORDER; ++order)
440                 seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
441         seq_putc(m, '\n');
442 }
443
444 /*
445  * This walks the free areas for each zone.
446  */
447 static int frag_show(struct seq_file *m, void *arg)
448 {
449         pg_data_t *pgdat = (pg_data_t *)arg;
450         walk_zones_in_node(m, pgdat, frag_show_print);
451         return 0;
452 }
453
454 static void pagetypeinfo_showfree_print(struct seq_file *m,
455                                         pg_data_t *pgdat, struct zone *zone)
456 {
457         int order, mtype;
458
459         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
460                 seq_printf(m, "Node %4d, zone %8s, type %12s ",
461                                         pgdat->node_id,
462                                         zone->name,
463                                         migratetype_names[mtype]);
464                 for (order = 0; order < MAX_ORDER; ++order) {
465                         unsigned long freecount = 0;
466                         struct free_area *area;
467                         struct list_head *curr;
468
469                         area = &(zone->free_area[order]);
470
471                         list_for_each(curr, &area->free_list[mtype])
472                                 freecount++;
473                         seq_printf(m, "%6lu ", freecount);
474                 }
475                 seq_putc(m, '\n');
476         }
477 }
478
479 /* Print out the free pages at each order for each migatetype */
480 static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
481 {
482         int order;
483         pg_data_t *pgdat = (pg_data_t *)arg;
484
485         /* Print header */
486         seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
487         for (order = 0; order < MAX_ORDER; ++order)
488                 seq_printf(m, "%6d ", order);
489         seq_putc(m, '\n');
490
491         walk_zones_in_node(m, pgdat, pagetypeinfo_showfree_print);
492
493         return 0;
494 }
495
496 static void pagetypeinfo_showblockcount_print(struct seq_file *m,
497                                         pg_data_t *pgdat, struct zone *zone)
498 {
499         int mtype;
500         unsigned long pfn;
501         unsigned long start_pfn = zone->zone_start_pfn;
502         unsigned long end_pfn = start_pfn + zone->spanned_pages;
503         unsigned long count[MIGRATE_TYPES] = { 0, };
504
505         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
506                 struct page *page;
507
508                 if (!pfn_valid(pfn))
509                         continue;
510
511                 page = pfn_to_page(pfn);
512                 mtype = get_pageblock_migratetype(page);
513
514                 count[mtype]++;
515         }
516
517         /* Print counts */
518         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
519         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
520                 seq_printf(m, "%12lu ", count[mtype]);
521         seq_putc(m, '\n');
522 }
523
524 /* Print out the free pages at each order for each migratetype */
525 static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
526 {
527         int mtype;
528         pg_data_t *pgdat = (pg_data_t *)arg;
529
530         seq_printf(m, "\n%-23s", "Number of blocks type ");
531         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
532                 seq_printf(m, "%12s ", migratetype_names[mtype]);
533         seq_putc(m, '\n');
534         walk_zones_in_node(m, pgdat, pagetypeinfo_showblockcount_print);
535
536         return 0;
537 }
538
539 /*
540  * This prints out statistics in relation to grouping pages by mobility.
541  * It is expensive to collect so do not constantly read the file.
542  */
543 static int pagetypeinfo_show(struct seq_file *m, void *arg)
544 {
545         pg_data_t *pgdat = (pg_data_t *)arg;
546
547         seq_printf(m, "Page block order: %d\n", pageblock_order);
548         seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
549         seq_putc(m, '\n');
550         pagetypeinfo_showfree(m, pgdat);
551         pagetypeinfo_showblockcount(m, pgdat);
552
553         return 0;
554 }
555
556 const struct seq_operations fragmentation_op = {
557         .start  = frag_start,
558         .next   = frag_next,
559         .stop   = frag_stop,
560         .show   = frag_show,
561 };
562
563 const struct seq_operations pagetypeinfo_op = {
564         .start  = frag_start,
565         .next   = frag_next,
566         .stop   = frag_stop,
567         .show   = pagetypeinfo_show,
568 };
569
570 #ifdef CONFIG_ZONE_DMA
571 #define TEXT_FOR_DMA(xx) xx "_dma",
572 #else
573 #define TEXT_FOR_DMA(xx)
574 #endif
575
576 #ifdef CONFIG_ZONE_DMA32
577 #define TEXT_FOR_DMA32(xx) xx "_dma32",
578 #else
579 #define TEXT_FOR_DMA32(xx)
580 #endif
581
582 #ifdef CONFIG_HIGHMEM
583 #define TEXT_FOR_HIGHMEM(xx) xx "_high",
584 #else
585 #define TEXT_FOR_HIGHMEM(xx)
586 #endif
587
588 #define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
589                                         TEXT_FOR_HIGHMEM(xx) xx "_movable",
590
591 static const char * const vmstat_text[] = {
592         /* Zoned VM counters */
593         "nr_free_pages",
594         "nr_inactive",
595         "nr_active",
596         "nr_anon_pages",
597         "nr_mapped",
598         "nr_file_pages",
599         "nr_dirty",
600         "nr_writeback",
601         "nr_slab_reclaimable",
602         "nr_slab_unreclaimable",
603         "nr_page_table_pages",
604         "nr_unstable",
605         "nr_bounce",
606         "nr_vmscan_write",
607
608 #ifdef CONFIG_NUMA
609         "numa_hit",
610         "numa_miss",
611         "numa_foreign",
612         "numa_interleave",
613         "numa_local",
614         "numa_other",
615 #endif
616
617 #ifdef CONFIG_VM_EVENT_COUNTERS
618         "pgpgin",
619         "pgpgout",
620         "pswpin",
621         "pswpout",
622
623         TEXTS_FOR_ZONES("pgalloc")
624
625         "pgfree",
626         "pgactivate",
627         "pgdeactivate",
628
629         "pgfault",
630         "pgmajfault",
631
632         TEXTS_FOR_ZONES("pgrefill")
633         TEXTS_FOR_ZONES("pgsteal")
634         TEXTS_FOR_ZONES("pgscan_kswapd")
635         TEXTS_FOR_ZONES("pgscan_direct")
636
637         "pginodesteal",
638         "slabs_scanned",
639         "kswapd_steal",
640         "kswapd_inodesteal",
641         "pageoutrun",
642         "allocstall",
643
644         "pgrotated",
645 #endif
646 };
647
648 static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
649                                                         struct zone *zone)
650 {
651         int i;
652         seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
653         seq_printf(m,
654                    "\n  pages free     %lu"
655                    "\n        min      %lu"
656                    "\n        low      %lu"
657                    "\n        high     %lu"
658                    "\n        scanned  %lu (a: %lu i: %lu)"
659                    "\n        spanned  %lu"
660                    "\n        present  %lu",
661                    zone_page_state(zone, NR_FREE_PAGES),
662                    zone->pages_min,
663                    zone->pages_low,
664                    zone->pages_high,
665                    zone->pages_scanned,
666                    zone->nr_scan_active, zone->nr_scan_inactive,
667                    zone->spanned_pages,
668                    zone->present_pages);
669
670         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
671                 seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
672                                 zone_page_state(zone, i));
673
674         seq_printf(m,
675                    "\n        protection: (%lu",
676                    zone->lowmem_reserve[0]);
677         for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
678                 seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
679         seq_printf(m,
680                    ")"
681                    "\n  pagesets");
682         for_each_online_cpu(i) {
683                 struct per_cpu_pageset *pageset;
684                 int j;
685
686                 pageset = zone_pcp(zone, i);
687                 for (j = 0; j < ARRAY_SIZE(pageset->pcp); j++) {
688                         seq_printf(m,
689                                    "\n    cpu: %i pcp: %i"
690                                    "\n              count: %i"
691                                    "\n              high:  %i"
692                                    "\n              batch: %i",
693                                    i, j,
694                                    pageset->pcp[j].count,
695                                    pageset->pcp[j].high,
696                                    pageset->pcp[j].batch);
697                         }
698 #ifdef CONFIG_SMP
699                 seq_printf(m, "\n  vm stats threshold: %d",
700                                 pageset->stat_threshold);
701 #endif
702         }
703         seq_printf(m,
704                    "\n  all_unreclaimable: %u"
705                    "\n  prev_priority:     %i"
706                    "\n  start_pfn:         %lu",
707                    zone->all_unreclaimable,
708                    zone->prev_priority,
709                    zone->zone_start_pfn);
710         seq_putc(m, '\n');
711 }
712
713 /*
714  * Output information about zones in @pgdat.
715  */
716 static int zoneinfo_show(struct seq_file *m, void *arg)
717 {
718         pg_data_t *pgdat = (pg_data_t *)arg;
719         walk_zones_in_node(m, pgdat, zoneinfo_show_print);
720         return 0;
721 }
722
723 const struct seq_operations zoneinfo_op = {
724         .start  = frag_start, /* iterate over all zones. The same as in
725                                * fragmentation. */
726         .next   = frag_next,
727         .stop   = frag_stop,
728         .show   = zoneinfo_show,
729 };
730
731 static void *vmstat_start(struct seq_file *m, loff_t *pos)
732 {
733         unsigned long *v;
734 #ifdef CONFIG_VM_EVENT_COUNTERS
735         unsigned long *e;
736 #endif
737         int i;
738
739         if (*pos >= ARRAY_SIZE(vmstat_text))
740                 return NULL;
741
742 #ifdef CONFIG_VM_EVENT_COUNTERS
743         v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long)
744                         + sizeof(struct vm_event_state), GFP_KERNEL);
745 #else
746         v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long),
747                         GFP_KERNEL);
748 #endif
749         m->private = v;
750         if (!v)
751                 return ERR_PTR(-ENOMEM);
752         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
753                 v[i] = global_page_state(i);
754 #ifdef CONFIG_VM_EVENT_COUNTERS
755         e = v + NR_VM_ZONE_STAT_ITEMS;
756         all_vm_events(e);
757         e[PGPGIN] /= 2;         /* sectors -> kbytes */
758         e[PGPGOUT] /= 2;
759 #endif
760         return v + *pos;
761 }
762
763 static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
764 {
765         (*pos)++;
766         if (*pos >= ARRAY_SIZE(vmstat_text))
767                 return NULL;
768         return (unsigned long *)m->private + *pos;
769 }
770
771 static int vmstat_show(struct seq_file *m, void *arg)
772 {
773         unsigned long *l = arg;
774         unsigned long off = l - (unsigned long *)m->private;
775
776         seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
777         return 0;
778 }
779
780 static void vmstat_stop(struct seq_file *m, void *arg)
781 {
782         kfree(m->private);
783         m->private = NULL;
784 }
785
786 const struct seq_operations vmstat_op = {
787         .start  = vmstat_start,
788         .next   = vmstat_next,
789         .stop   = vmstat_stop,
790         .show   = vmstat_show,
791 };
792
793 #endif /* CONFIG_PROC_FS */
794
795 #ifdef CONFIG_SMP
796 static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
797 int sysctl_stat_interval __read_mostly = HZ;
798
799 static void vmstat_update(struct work_struct *w)
800 {
801         refresh_cpu_vm_stats(smp_processor_id());
802         schedule_delayed_work(&__get_cpu_var(vmstat_work),
803                 sysctl_stat_interval);
804 }
805
806 static void __devinit start_cpu_timer(int cpu)
807 {
808         struct delayed_work *vmstat_work = &per_cpu(vmstat_work, cpu);
809
810         INIT_DELAYED_WORK_DEFERRABLE(vmstat_work, vmstat_update);
811         schedule_delayed_work_on(cpu, vmstat_work, HZ + cpu);
812 }
813
814 /*
815  * Use the cpu notifier to insure that the thresholds are recalculated
816  * when necessary.
817  */
818 static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
819                 unsigned long action,
820                 void *hcpu)
821 {
822         long cpu = (long)hcpu;
823
824         switch (action) {
825         case CPU_ONLINE:
826         case CPU_ONLINE_FROZEN:
827                 start_cpu_timer(cpu);
828                 break;
829         case CPU_DOWN_PREPARE:
830         case CPU_DOWN_PREPARE_FROZEN:
831                 cancel_rearming_delayed_work(&per_cpu(vmstat_work, cpu));
832                 per_cpu(vmstat_work, cpu).work.func = NULL;
833                 break;
834         case CPU_DOWN_FAILED:
835         case CPU_DOWN_FAILED_FROZEN:
836                 start_cpu_timer(cpu);
837                 break;
838         case CPU_DEAD:
839         case CPU_DEAD_FROZEN:
840                 refresh_zone_stat_thresholds();
841                 break;
842         default:
843                 break;
844         }
845         return NOTIFY_OK;
846 }
847
848 static struct notifier_block __cpuinitdata vmstat_notifier =
849         { &vmstat_cpuup_callback, NULL, 0 };
850
851 static int __init setup_vmstat(void)
852 {
853         int cpu;
854
855         refresh_zone_stat_thresholds();
856         register_cpu_notifier(&vmstat_notifier);
857
858         for_each_online_cpu(cpu)
859                 start_cpu_timer(cpu);
860         return 0;
861 }
862 module_init(setup_vmstat)
863 #endif