vmstat.c revision e2fc88d0643ca68f2011e6db4aa31e22bd94210c 
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
19DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
20EXPORT_PER_CPU_SYMBOL(vm_event_states);
21
22static 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*/
49void all_vm_events(unsigned long *ret)
50{
51	sum_vm_events(ret, &cpu_online_map);
52}
53EXPORT_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 */
62void 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 */
81atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
82EXPORT_SYMBOL(vm_stat);
83
84#ifdef CONFIG_SMP
85
86static 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 */
136static 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 */
157void __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}
172EXPORT_SYMBOL(__mod_zone_page_state);
173
174/*
175 * For an unknown interrupt state
176 */
177void 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}
186EXPORT_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 */
211void __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
226void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
227{
228	__inc_zone_state(page_zone(page), item);
229}
230EXPORT_SYMBOL(__inc_zone_page_state);
231
232void __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
247void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
248{
249	__dec_zone_state(page_zone(page), item);
250}
251EXPORT_SYMBOL(__dec_zone_page_state);
252
253void 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
262void 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}
272EXPORT_SYMBOL(inc_zone_page_state);
273
274void 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}
282EXPORT_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 */
298void 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 */
365void 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
384static char * const migratetype_names[MIGRATE_TYPES] = {
385	"Unmovable",
386	"Reclaimable",
387	"Movable",
388	"Reserve",
389};
390
391static 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
403static 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
411static 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 */
416static 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
433static 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 */
447static 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
454static 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 */
480static 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
496static 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 */
525static 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 */
543static 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
556const struct seq_operations fragmentation_op = {
557	.start	= frag_start,
558	.next	= frag_next,
559	.stop	= frag_stop,
560	.show	= frag_show,
561};
562
563const 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
591static 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
648static 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 */
716static 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
723const 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
731static 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
763static 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
771static 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
780static void vmstat_stop(struct seq_file *m, void *arg)
781{
782	kfree(m->private);
783	m->private = NULL;
784}
785
786const 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
796static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
797int sysctl_stat_interval __read_mostly = HZ;
798
799static 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
806static 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 */
818static 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
848static struct notifier_block __cpuinitdata vmstat_notifier =
849	{ &vmstat_cpuup_callback, NULL, 0 };
850
851static 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}
862module_init(setup_vmstat)
863#endif
864