vmstat.c revision 4b51d66989218aad731a721b5b28c79bf5388c09 
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/module.h>
14#include <linux/cpu.h>
15
16#ifdef CONFIG_VM_EVENT_COUNTERS
17DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
18EXPORT_PER_CPU_SYMBOL(vm_event_states);
19
20static void sum_vm_events(unsigned long *ret, cpumask_t *cpumask)
21{
22	int cpu = 0;
23	int i;
24
25	memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
26
27	cpu = first_cpu(*cpumask);
28	while (cpu < NR_CPUS) {
29		struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
30
31		cpu = next_cpu(cpu, *cpumask);
32
33		if (cpu < NR_CPUS)
34			prefetch(&per_cpu(vm_event_states, cpu));
35
36
37		for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
38			ret[i] += this->event[i];
39	}
40}
41
42/*
43 * Accumulate the vm event counters across all CPUs.
44 * The result is unavoidably approximate - it can change
45 * during and after execution of this function.
46*/
47void all_vm_events(unsigned long *ret)
48{
49	sum_vm_events(ret, &cpu_online_map);
50}
51EXPORT_SYMBOL_GPL(all_vm_events);
52
53#ifdef CONFIG_HOTPLUG
54/*
55 * Fold the foreign cpu events into our own.
56 *
57 * This is adding to the events on one processor
58 * but keeps the global counts constant.
59 */
60void vm_events_fold_cpu(int cpu)
61{
62	struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
63	int i;
64
65	for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
66		count_vm_events(i, fold_state->event[i]);
67		fold_state->event[i] = 0;
68	}
69}
70#endif /* CONFIG_HOTPLUG */
71
72#endif /* CONFIG_VM_EVENT_COUNTERS */
73
74/*
75 * Manage combined zone based / global counters
76 *
77 * vm_stat contains the global counters
78 */
79atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
80EXPORT_SYMBOL(vm_stat);
81
82#ifdef CONFIG_SMP
83
84static int calculate_threshold(struct zone *zone)
85{
86	int threshold;
87	int mem;	/* memory in 128 MB units */
88
89	/*
90	 * The threshold scales with the number of processors and the amount
91	 * of memory per zone. More memory means that we can defer updates for
92	 * longer, more processors could lead to more contention.
93 	 * fls() is used to have a cheap way of logarithmic scaling.
94	 *
95	 * Some sample thresholds:
96	 *
97	 * Threshold	Processors	(fls)	Zonesize	fls(mem+1)
98	 * ------------------------------------------------------------------
99	 * 8		1		1	0.9-1 GB	4
100	 * 16		2		2	0.9-1 GB	4
101	 * 20 		2		2	1-2 GB		5
102	 * 24		2		2	2-4 GB		6
103	 * 28		2		2	4-8 GB		7
104	 * 32		2		2	8-16 GB		8
105	 * 4		2		2	<128M		1
106	 * 30		4		3	2-4 GB		5
107	 * 48		4		3	8-16 GB		8
108	 * 32		8		4	1-2 GB		4
109	 * 32		8		4	0.9-1GB		4
110	 * 10		16		5	<128M		1
111	 * 40		16		5	900M		4
112	 * 70		64		7	2-4 GB		5
113	 * 84		64		7	4-8 GB		6
114	 * 108		512		9	4-8 GB		6
115	 * 125		1024		10	8-16 GB		8
116	 * 125		1024		10	16-32 GB	9
117	 */
118
119	mem = zone->present_pages >> (27 - PAGE_SHIFT);
120
121	threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
122
123	/*
124	 * Maximum threshold is 125
125	 */
126	threshold = min(125, threshold);
127
128	return threshold;
129}
130
131/*
132 * Refresh the thresholds for each zone.
133 */
134static void refresh_zone_stat_thresholds(void)
135{
136	struct zone *zone;
137	int cpu;
138	int threshold;
139
140	for_each_zone(zone) {
141
142		if (!zone->present_pages)
143			continue;
144
145		threshold = calculate_threshold(zone);
146
147		for_each_online_cpu(cpu)
148			zone_pcp(zone, cpu)->stat_threshold = threshold;
149	}
150}
151
152/*
153 * For use when we know that interrupts are disabled.
154 */
155void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
156				int delta)
157{
158	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
159	s8 *p = pcp->vm_stat_diff + item;
160	long x;
161
162	x = delta + *p;
163
164	if (unlikely(x > pcp->stat_threshold || x < -pcp->stat_threshold)) {
165		zone_page_state_add(x, zone, item);
166		x = 0;
167	}
168	*p = x;
169}
170EXPORT_SYMBOL(__mod_zone_page_state);
171
172/*
173 * For an unknown interrupt state
174 */
175void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
176					int delta)
177{
178	unsigned long flags;
179
180	local_irq_save(flags);
181	__mod_zone_page_state(zone, item, delta);
182	local_irq_restore(flags);
183}
184EXPORT_SYMBOL(mod_zone_page_state);
185
186/*
187 * Optimized increment and decrement functions.
188 *
189 * These are only for a single page and therefore can take a struct page *
190 * argument instead of struct zone *. This allows the inclusion of the code
191 * generated for page_zone(page) into the optimized functions.
192 *
193 * No overflow check is necessary and therefore the differential can be
194 * incremented or decremented in place which may allow the compilers to
195 * generate better code.
196 * The increment or decrement is known and therefore one boundary check can
197 * be omitted.
198 *
199 * NOTE: These functions are very performance sensitive. Change only
200 * with care.
201 *
202 * Some processors have inc/dec instructions that are atomic vs an interrupt.
203 * However, the code must first determine the differential location in a zone
204 * based on the processor number and then inc/dec the counter. There is no
205 * guarantee without disabling preemption that the processor will not change
206 * in between and therefore the atomicity vs. interrupt cannot be exploited
207 * in a useful way here.
208 */
209void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
210{
211	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
212	s8 *p = pcp->vm_stat_diff + item;
213
214	(*p)++;
215
216	if (unlikely(*p > pcp->stat_threshold)) {
217		int overstep = pcp->stat_threshold / 2;
218
219		zone_page_state_add(*p + overstep, zone, item);
220		*p = -overstep;
221	}
222}
223
224void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
225{
226	__inc_zone_state(page_zone(page), item);
227}
228EXPORT_SYMBOL(__inc_zone_page_state);
229
230void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
231{
232	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
233	s8 *p = pcp->vm_stat_diff + item;
234
235	(*p)--;
236
237	if (unlikely(*p < - pcp->stat_threshold)) {
238		int overstep = pcp->stat_threshold / 2;
239
240		zone_page_state_add(*p - overstep, zone, item);
241		*p = overstep;
242	}
243}
244
245void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
246{
247	__dec_zone_state(page_zone(page), item);
248}
249EXPORT_SYMBOL(__dec_zone_page_state);
250
251void inc_zone_state(struct zone *zone, enum zone_stat_item item)
252{
253	unsigned long flags;
254
255	local_irq_save(flags);
256	__inc_zone_state(zone, item);
257	local_irq_restore(flags);
258}
259
260void inc_zone_page_state(struct page *page, enum zone_stat_item item)
261{
262	unsigned long flags;
263	struct zone *zone;
264
265	zone = page_zone(page);
266	local_irq_save(flags);
267	__inc_zone_state(zone, item);
268	local_irq_restore(flags);
269}
270EXPORT_SYMBOL(inc_zone_page_state);
271
272void dec_zone_page_state(struct page *page, enum zone_stat_item item)
273{
274	unsigned long flags;
275
276	local_irq_save(flags);
277	__dec_zone_page_state(page, item);
278	local_irq_restore(flags);
279}
280EXPORT_SYMBOL(dec_zone_page_state);
281
282/*
283 * Update the zone counters for one cpu.
284 */
285void refresh_cpu_vm_stats(int cpu)
286{
287	struct zone *zone;
288	int i;
289	unsigned long flags;
290
291	for_each_zone(zone) {
292		struct per_cpu_pageset *pcp;
293
294		if (!populated_zone(zone))
295			continue;
296
297		pcp = zone_pcp(zone, cpu);
298
299		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
300			if (pcp->vm_stat_diff[i]) {
301				local_irq_save(flags);
302				zone_page_state_add(pcp->vm_stat_diff[i],
303					zone, i);
304				pcp->vm_stat_diff[i] = 0;
305				local_irq_restore(flags);
306			}
307	}
308}
309
310static void __refresh_cpu_vm_stats(void *dummy)
311{
312	refresh_cpu_vm_stats(smp_processor_id());
313}
314
315/*
316 * Consolidate all counters.
317 *
318 * Note that the result is less inaccurate but still inaccurate
319 * if concurrent processes are allowed to run.
320 */
321void refresh_vm_stats(void)
322{
323	on_each_cpu(__refresh_cpu_vm_stats, NULL, 0, 1);
324}
325EXPORT_SYMBOL(refresh_vm_stats);
326
327#endif
328
329#ifdef CONFIG_NUMA
330/*
331 * zonelist = the list of zones passed to the allocator
332 * z 	    = the zone from which the allocation occurred.
333 *
334 * Must be called with interrupts disabled.
335 */
336void zone_statistics(struct zonelist *zonelist, struct zone *z)
337{
338	if (z->zone_pgdat == zonelist->zones[0]->zone_pgdat) {
339		__inc_zone_state(z, NUMA_HIT);
340	} else {
341		__inc_zone_state(z, NUMA_MISS);
342		__inc_zone_state(zonelist->zones[0], NUMA_FOREIGN);
343	}
344	if (z->node == numa_node_id())
345		__inc_zone_state(z, NUMA_LOCAL);
346	else
347		__inc_zone_state(z, NUMA_OTHER);
348}
349#endif
350
351#ifdef CONFIG_PROC_FS
352
353#include <linux/seq_file.h>
354
355static void *frag_start(struct seq_file *m, loff_t *pos)
356{
357	pg_data_t *pgdat;
358	loff_t node = *pos;
359	for (pgdat = first_online_pgdat();
360	     pgdat && node;
361	     pgdat = next_online_pgdat(pgdat))
362		--node;
363
364	return pgdat;
365}
366
367static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
368{
369	pg_data_t *pgdat = (pg_data_t *)arg;
370
371	(*pos)++;
372	return next_online_pgdat(pgdat);
373}
374
375static void frag_stop(struct seq_file *m, void *arg)
376{
377}
378
379/*
380 * This walks the free areas for each zone.
381 */
382static int frag_show(struct seq_file *m, void *arg)
383{
384	pg_data_t *pgdat = (pg_data_t *)arg;
385	struct zone *zone;
386	struct zone *node_zones = pgdat->node_zones;
387	unsigned long flags;
388	int order;
389
390	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
391		if (!populated_zone(zone))
392			continue;
393
394		spin_lock_irqsave(&zone->lock, flags);
395		seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
396		for (order = 0; order < MAX_ORDER; ++order)
397			seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
398		spin_unlock_irqrestore(&zone->lock, flags);
399		seq_putc(m, '\n');
400	}
401	return 0;
402}
403
404const struct seq_operations fragmentation_op = {
405	.start	= frag_start,
406	.next	= frag_next,
407	.stop	= frag_stop,
408	.show	= frag_show,
409};
410
411#ifdef CONFIG_ZONE_DMA
412#define TEXT_FOR_DMA(xx) xx "_dma",
413#else
414#define TEXT_FOR_DMA(xx)
415#endif
416
417#ifdef CONFIG_ZONE_DMA32
418#define TEXT_FOR_DMA32(xx) xx "_dma32",
419#else
420#define TEXT_FOR_DMA32(xx)
421#endif
422
423#ifdef CONFIG_HIGHMEM
424#define TEXT_FOR_HIGHMEM(xx) xx "_high",
425#else
426#define TEXT_FOR_HIGHMEM(xx)
427#endif
428
429#define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
430					TEXT_FOR_HIGHMEM(xx)
431
432static const char * const vmstat_text[] = {
433	/* Zoned VM counters */
434	"nr_free_pages",
435	"nr_active",
436	"nr_inactive",
437	"nr_anon_pages",
438	"nr_mapped",
439	"nr_file_pages",
440	"nr_dirty",
441	"nr_writeback",
442	"nr_slab_reclaimable",
443	"nr_slab_unreclaimable",
444	"nr_page_table_pages",
445	"nr_unstable",
446	"nr_bounce",
447	"nr_vmscan_write",
448
449#ifdef CONFIG_NUMA
450	"numa_hit",
451	"numa_miss",
452	"numa_foreign",
453	"numa_interleave",
454	"numa_local",
455	"numa_other",
456#endif
457
458#ifdef CONFIG_VM_EVENT_COUNTERS
459	"pgpgin",
460	"pgpgout",
461	"pswpin",
462	"pswpout",
463
464	TEXTS_FOR_ZONES("pgalloc")
465
466	"pgfree",
467	"pgactivate",
468	"pgdeactivate",
469
470	"pgfault",
471	"pgmajfault",
472
473	TEXTS_FOR_ZONES("pgrefill")
474	TEXTS_FOR_ZONES("pgsteal")
475	TEXTS_FOR_ZONES("pgscan_kswapd")
476	TEXTS_FOR_ZONES("pgscan_direct")
477
478	"pginodesteal",
479	"slabs_scanned",
480	"kswapd_steal",
481	"kswapd_inodesteal",
482	"pageoutrun",
483	"allocstall",
484
485	"pgrotated",
486#endif
487};
488
489/*
490 * Output information about zones in @pgdat.
491 */
492static int zoneinfo_show(struct seq_file *m, void *arg)
493{
494	pg_data_t *pgdat = arg;
495	struct zone *zone;
496	struct zone *node_zones = pgdat->node_zones;
497	unsigned long flags;
498
499	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; zone++) {
500		int i;
501
502		if (!populated_zone(zone))
503			continue;
504
505		spin_lock_irqsave(&zone->lock, flags);
506		seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
507		seq_printf(m,
508			   "\n  pages free     %lu"
509			   "\n        min      %lu"
510			   "\n        low      %lu"
511			   "\n        high     %lu"
512			   "\n        scanned  %lu (a: %lu i: %lu)"
513			   "\n        spanned  %lu"
514			   "\n        present  %lu",
515			   zone_page_state(zone, NR_FREE_PAGES),
516			   zone->pages_min,
517			   zone->pages_low,
518			   zone->pages_high,
519			   zone->pages_scanned,
520			   zone->nr_scan_active, zone->nr_scan_inactive,
521			   zone->spanned_pages,
522			   zone->present_pages);
523
524		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
525			seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
526					zone_page_state(zone, i));
527
528		seq_printf(m,
529			   "\n        protection: (%lu",
530			   zone->lowmem_reserve[0]);
531		for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
532			seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
533		seq_printf(m,
534			   ")"
535			   "\n  pagesets");
536		for_each_online_cpu(i) {
537			struct per_cpu_pageset *pageset;
538			int j;
539
540			pageset = zone_pcp(zone, i);
541			for (j = 0; j < ARRAY_SIZE(pageset->pcp); j++) {
542				seq_printf(m,
543					   "\n    cpu: %i pcp: %i"
544					   "\n              count: %i"
545					   "\n              high:  %i"
546					   "\n              batch: %i",
547					   i, j,
548					   pageset->pcp[j].count,
549					   pageset->pcp[j].high,
550					   pageset->pcp[j].batch);
551			}
552#ifdef CONFIG_SMP
553			seq_printf(m, "\n  vm stats threshold: %d",
554					pageset->stat_threshold);
555#endif
556		}
557		seq_printf(m,
558			   "\n  all_unreclaimable: %u"
559			   "\n  prev_priority:     %i"
560			   "\n  start_pfn:         %lu",
561			   zone->all_unreclaimable,
562			   zone->prev_priority,
563			   zone->zone_start_pfn);
564		spin_unlock_irqrestore(&zone->lock, flags);
565		seq_putc(m, '\n');
566	}
567	return 0;
568}
569
570const struct seq_operations zoneinfo_op = {
571	.start	= frag_start, /* iterate over all zones. The same as in
572			       * fragmentation. */
573	.next	= frag_next,
574	.stop	= frag_stop,
575	.show	= zoneinfo_show,
576};
577
578static void *vmstat_start(struct seq_file *m, loff_t *pos)
579{
580	unsigned long *v;
581#ifdef CONFIG_VM_EVENT_COUNTERS
582	unsigned long *e;
583#endif
584	int i;
585
586	if (*pos >= ARRAY_SIZE(vmstat_text))
587		return NULL;
588
589#ifdef CONFIG_VM_EVENT_COUNTERS
590	v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long)
591			+ sizeof(struct vm_event_state), GFP_KERNEL);
592#else
593	v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long),
594			GFP_KERNEL);
595#endif
596	m->private = v;
597	if (!v)
598		return ERR_PTR(-ENOMEM);
599	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
600		v[i] = global_page_state(i);
601#ifdef CONFIG_VM_EVENT_COUNTERS
602	e = v + NR_VM_ZONE_STAT_ITEMS;
603	all_vm_events(e);
604	e[PGPGIN] /= 2;		/* sectors -> kbytes */
605	e[PGPGOUT] /= 2;
606#endif
607	return v + *pos;
608}
609
610static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
611{
612	(*pos)++;
613	if (*pos >= ARRAY_SIZE(vmstat_text))
614		return NULL;
615	return (unsigned long *)m->private + *pos;
616}
617
618static int vmstat_show(struct seq_file *m, void *arg)
619{
620	unsigned long *l = arg;
621	unsigned long off = l - (unsigned long *)m->private;
622
623	seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
624	return 0;
625}
626
627static void vmstat_stop(struct seq_file *m, void *arg)
628{
629	kfree(m->private);
630	m->private = NULL;
631}
632
633const struct seq_operations vmstat_op = {
634	.start	= vmstat_start,
635	.next	= vmstat_next,
636	.stop	= vmstat_stop,
637	.show	= vmstat_show,
638};
639
640#endif /* CONFIG_PROC_FS */
641
642#ifdef CONFIG_SMP
643/*
644 * Use the cpu notifier to insure that the thresholds are recalculated
645 * when necessary.
646 */
647static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
648		unsigned long action,
649		void *hcpu)
650{
651	switch (action) {
652	case CPU_UP_PREPARE:
653	case CPU_UP_CANCELED:
654	case CPU_DEAD:
655		refresh_zone_stat_thresholds();
656		break;
657	default:
658		break;
659	}
660	return NOTIFY_OK;
661}
662
663static struct notifier_block __cpuinitdata vmstat_notifier =
664	{ &vmstat_cpuup_callback, NULL, 0 };
665
666int __init setup_vmstat(void)
667{
668	refresh_zone_stat_thresholds();
669	register_cpu_notifier(&vmstat_notifier);
670	return 0;
671}
672module_init(setup_vmstat)
673#endif
674