xref: /openbmc/linux/mm/vmstat.c (revision 22246614)
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;
25 	int i;
26 
27 	memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
28 
29 	for_each_cpu_mask(cpu, *cpumask) {
30 		struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
31 
32 		for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
33 			ret[i] += this->event[i];
34 	}
35 }
36 
37 /*
38  * Accumulate the vm event counters across all CPUs.
39  * The result is unavoidably approximate - it can change
40  * during and after execution of this function.
41 */
42 void all_vm_events(unsigned long *ret)
43 {
44 	get_online_cpus();
45 	sum_vm_events(ret, &cpu_online_map);
46 	put_online_cpus();
47 }
48 EXPORT_SYMBOL_GPL(all_vm_events);
49 
50 #ifdef CONFIG_HOTPLUG
51 /*
52  * Fold the foreign cpu events into our own.
53  *
54  * This is adding to the events on one processor
55  * but keeps the global counts constant.
56  */
57 void vm_events_fold_cpu(int cpu)
58 {
59 	struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
60 	int i;
61 
62 	for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
63 		count_vm_events(i, fold_state->event[i]);
64 		fold_state->event[i] = 0;
65 	}
66 }
67 #endif /* CONFIG_HOTPLUG */
68 
69 #endif /* CONFIG_VM_EVENT_COUNTERS */
70 
71 /*
72  * Manage combined zone based / global counters
73  *
74  * vm_stat contains the global counters
75  */
76 atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
77 EXPORT_SYMBOL(vm_stat);
78 
79 #ifdef CONFIG_SMP
80 
81 static int calculate_threshold(struct zone *zone)
82 {
83 	int threshold;
84 	int mem;	/* memory in 128 MB units */
85 
86 	/*
87 	 * The threshold scales with the number of processors and the amount
88 	 * of memory per zone. More memory means that we can defer updates for
89 	 * longer, more processors could lead to more contention.
90  	 * fls() is used to have a cheap way of logarithmic scaling.
91 	 *
92 	 * Some sample thresholds:
93 	 *
94 	 * Threshold	Processors	(fls)	Zonesize	fls(mem+1)
95 	 * ------------------------------------------------------------------
96 	 * 8		1		1	0.9-1 GB	4
97 	 * 16		2		2	0.9-1 GB	4
98 	 * 20 		2		2	1-2 GB		5
99 	 * 24		2		2	2-4 GB		6
100 	 * 28		2		2	4-8 GB		7
101 	 * 32		2		2	8-16 GB		8
102 	 * 4		2		2	<128M		1
103 	 * 30		4		3	2-4 GB		5
104 	 * 48		4		3	8-16 GB		8
105 	 * 32		8		4	1-2 GB		4
106 	 * 32		8		4	0.9-1GB		4
107 	 * 10		16		5	<128M		1
108 	 * 40		16		5	900M		4
109 	 * 70		64		7	2-4 GB		5
110 	 * 84		64		7	4-8 GB		6
111 	 * 108		512		9	4-8 GB		6
112 	 * 125		1024		10	8-16 GB		8
113 	 * 125		1024		10	16-32 GB	9
114 	 */
115 
116 	mem = zone->present_pages >> (27 - PAGE_SHIFT);
117 
118 	threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
119 
120 	/*
121 	 * Maximum threshold is 125
122 	 */
123 	threshold = min(125, threshold);
124 
125 	return threshold;
126 }
127 
128 /*
129  * Refresh the thresholds for each zone.
130  */
131 static void refresh_zone_stat_thresholds(void)
132 {
133 	struct zone *zone;
134 	int cpu;
135 	int threshold;
136 
137 	for_each_zone(zone) {
138 
139 		if (!zone->present_pages)
140 			continue;
141 
142 		threshold = calculate_threshold(zone);
143 
144 		for_each_online_cpu(cpu)
145 			zone_pcp(zone, cpu)->stat_threshold = threshold;
146 	}
147 }
148 
149 /*
150  * For use when we know that interrupts are disabled.
151  */
152 void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
153 				int delta)
154 {
155 	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
156 	s8 *p = pcp->vm_stat_diff + item;
157 	long x;
158 
159 	x = delta + *p;
160 
161 	if (unlikely(x > pcp->stat_threshold || x < -pcp->stat_threshold)) {
162 		zone_page_state_add(x, zone, item);
163 		x = 0;
164 	}
165 	*p = x;
166 }
167 EXPORT_SYMBOL(__mod_zone_page_state);
168 
169 /*
170  * For an unknown interrupt state
171  */
172 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
173 					int delta)
174 {
175 	unsigned long flags;
176 
177 	local_irq_save(flags);
178 	__mod_zone_page_state(zone, item, delta);
179 	local_irq_restore(flags);
180 }
181 EXPORT_SYMBOL(mod_zone_page_state);
182 
183 /*
184  * Optimized increment and decrement functions.
185  *
186  * These are only for a single page and therefore can take a struct page *
187  * argument instead of struct zone *. This allows the inclusion of the code
188  * generated for page_zone(page) into the optimized functions.
189  *
190  * No overflow check is necessary and therefore the differential can be
191  * incremented or decremented in place which may allow the compilers to
192  * generate better code.
193  * The increment or decrement is known and therefore one boundary check can
194  * be omitted.
195  *
196  * NOTE: These functions are very performance sensitive. Change only
197  * with care.
198  *
199  * Some processors have inc/dec instructions that are atomic vs an interrupt.
200  * However, the code must first determine the differential location in a zone
201  * based on the processor number and then inc/dec the counter. There is no
202  * guarantee without disabling preemption that the processor will not change
203  * in between and therefore the atomicity vs. interrupt cannot be exploited
204  * in a useful way here.
205  */
206 void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
207 {
208 	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
209 	s8 *p = pcp->vm_stat_diff + item;
210 
211 	(*p)++;
212 
213 	if (unlikely(*p > pcp->stat_threshold)) {
214 		int overstep = pcp->stat_threshold / 2;
215 
216 		zone_page_state_add(*p + overstep, zone, item);
217 		*p = -overstep;
218 	}
219 }
220 
221 void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
222 {
223 	__inc_zone_state(page_zone(page), item);
224 }
225 EXPORT_SYMBOL(__inc_zone_page_state);
226 
227 void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
228 {
229 	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
230 	s8 *p = pcp->vm_stat_diff + item;
231 
232 	(*p)--;
233 
234 	if (unlikely(*p < - pcp->stat_threshold)) {
235 		int overstep = pcp->stat_threshold / 2;
236 
237 		zone_page_state_add(*p - overstep, zone, item);
238 		*p = overstep;
239 	}
240 }
241 
242 void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
243 {
244 	__dec_zone_state(page_zone(page), item);
245 }
246 EXPORT_SYMBOL(__dec_zone_page_state);
247 
248 void inc_zone_state(struct zone *zone, enum zone_stat_item item)
249 {
250 	unsigned long flags;
251 
252 	local_irq_save(flags);
253 	__inc_zone_state(zone, item);
254 	local_irq_restore(flags);
255 }
256 
257 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
258 {
259 	unsigned long flags;
260 	struct zone *zone;
261 
262 	zone = page_zone(page);
263 	local_irq_save(flags);
264 	__inc_zone_state(zone, item);
265 	local_irq_restore(flags);
266 }
267 EXPORT_SYMBOL(inc_zone_page_state);
268 
269 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
270 {
271 	unsigned long flags;
272 
273 	local_irq_save(flags);
274 	__dec_zone_page_state(page, item);
275 	local_irq_restore(flags);
276 }
277 EXPORT_SYMBOL(dec_zone_page_state);
278 
279 /*
280  * Update the zone counters for one cpu.
281  *
282  * The cpu specified must be either the current cpu or a processor that
283  * is not online. If it is the current cpu then the execution thread must
284  * be pinned to the current cpu.
285  *
286  * Note that refresh_cpu_vm_stats strives to only access
287  * node local memory. The per cpu pagesets on remote zones are placed
288  * in the memory local to the processor using that pageset. So the
289  * loop over all zones will access a series of cachelines local to
290  * the processor.
291  *
292  * The call to zone_page_state_add updates the cachelines with the
293  * statistics in the remote zone struct as well as the global cachelines
294  * with the global counters. These could cause remote node cache line
295  * bouncing and will have to be only done when necessary.
296  */
297 void refresh_cpu_vm_stats(int cpu)
298 {
299 	struct zone *zone;
300 	int i;
301 	int global_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
302 
303 	for_each_zone(zone) {
304 		struct per_cpu_pageset *p;
305 
306 		if (!populated_zone(zone))
307 			continue;
308 
309 		p = zone_pcp(zone, cpu);
310 
311 		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
312 			if (p->vm_stat_diff[i]) {
313 				unsigned long flags;
314 				int v;
315 
316 				local_irq_save(flags);
317 				v = p->vm_stat_diff[i];
318 				p->vm_stat_diff[i] = 0;
319 				local_irq_restore(flags);
320 				atomic_long_add(v, &zone->vm_stat[i]);
321 				global_diff[i] += v;
322 #ifdef CONFIG_NUMA
323 				/* 3 seconds idle till flush */
324 				p->expire = 3;
325 #endif
326 			}
327 		cond_resched();
328 #ifdef CONFIG_NUMA
329 		/*
330 		 * Deal with draining the remote pageset of this
331 		 * processor
332 		 *
333 		 * Check if there are pages remaining in this pageset
334 		 * if not then there is nothing to expire.
335 		 */
336 		if (!p->expire || !p->pcp.count)
337 			continue;
338 
339 		/*
340 		 * We never drain zones local to this processor.
341 		 */
342 		if (zone_to_nid(zone) == numa_node_id()) {
343 			p->expire = 0;
344 			continue;
345 		}
346 
347 		p->expire--;
348 		if (p->expire)
349 			continue;
350 
351 		if (p->pcp.count)
352 			drain_zone_pages(zone, &p->pcp);
353 #endif
354 	}
355 
356 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
357 		if (global_diff[i])
358 			atomic_long_add(global_diff[i], &vm_stat[i]);
359 }
360 
361 #endif
362 
363 #ifdef CONFIG_NUMA
364 /*
365  * zonelist = the list of zones passed to the allocator
366  * z 	    = the zone from which the allocation occurred.
367  *
368  * Must be called with interrupts disabled.
369  */
370 void zone_statistics(struct zone *preferred_zone, struct zone *z)
371 {
372 	if (z->zone_pgdat == preferred_zone->zone_pgdat) {
373 		__inc_zone_state(z, NUMA_HIT);
374 	} else {
375 		__inc_zone_state(z, NUMA_MISS);
376 		__inc_zone_state(preferred_zone, NUMA_FOREIGN);
377 	}
378 	if (z->node == numa_node_id())
379 		__inc_zone_state(z, NUMA_LOCAL);
380 	else
381 		__inc_zone_state(z, NUMA_OTHER);
382 }
383 #endif
384 
385 #ifdef CONFIG_PROC_FS
386 
387 #include <linux/seq_file.h>
388 
389 static char * const migratetype_names[MIGRATE_TYPES] = {
390 	"Unmovable",
391 	"Reclaimable",
392 	"Movable",
393 	"Reserve",
394 	"Isolate",
395 };
396 
397 static void *frag_start(struct seq_file *m, loff_t *pos)
398 {
399 	pg_data_t *pgdat;
400 	loff_t node = *pos;
401 	for (pgdat = first_online_pgdat();
402 	     pgdat && node;
403 	     pgdat = next_online_pgdat(pgdat))
404 		--node;
405 
406 	return pgdat;
407 }
408 
409 static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
410 {
411 	pg_data_t *pgdat = (pg_data_t *)arg;
412 
413 	(*pos)++;
414 	return next_online_pgdat(pgdat);
415 }
416 
417 static void frag_stop(struct seq_file *m, void *arg)
418 {
419 }
420 
421 /* Walk all the zones in a node and print using a callback */
422 static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
423 		void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
424 {
425 	struct zone *zone;
426 	struct zone *node_zones = pgdat->node_zones;
427 	unsigned long flags;
428 
429 	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
430 		if (!populated_zone(zone))
431 			continue;
432 
433 		spin_lock_irqsave(&zone->lock, flags);
434 		print(m, pgdat, zone);
435 		spin_unlock_irqrestore(&zone->lock, flags);
436 	}
437 }
438 
439 static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
440 						struct zone *zone)
441 {
442 	int order;
443 
444 	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
445 	for (order = 0; order < MAX_ORDER; ++order)
446 		seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
447 	seq_putc(m, '\n');
448 }
449 
450 /*
451  * This walks the free areas for each zone.
452  */
453 static int frag_show(struct seq_file *m, void *arg)
454 {
455 	pg_data_t *pgdat = (pg_data_t *)arg;
456 	walk_zones_in_node(m, pgdat, frag_show_print);
457 	return 0;
458 }
459 
460 static void pagetypeinfo_showfree_print(struct seq_file *m,
461 					pg_data_t *pgdat, struct zone *zone)
462 {
463 	int order, mtype;
464 
465 	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
466 		seq_printf(m, "Node %4d, zone %8s, type %12s ",
467 					pgdat->node_id,
468 					zone->name,
469 					migratetype_names[mtype]);
470 		for (order = 0; order < MAX_ORDER; ++order) {
471 			unsigned long freecount = 0;
472 			struct free_area *area;
473 			struct list_head *curr;
474 
475 			area = &(zone->free_area[order]);
476 
477 			list_for_each(curr, &area->free_list[mtype])
478 				freecount++;
479 			seq_printf(m, "%6lu ", freecount);
480 		}
481 		seq_putc(m, '\n');
482 	}
483 }
484 
485 /* Print out the free pages at each order for each migatetype */
486 static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
487 {
488 	int order;
489 	pg_data_t *pgdat = (pg_data_t *)arg;
490 
491 	/* Print header */
492 	seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
493 	for (order = 0; order < MAX_ORDER; ++order)
494 		seq_printf(m, "%6d ", order);
495 	seq_putc(m, '\n');
496 
497 	walk_zones_in_node(m, pgdat, pagetypeinfo_showfree_print);
498 
499 	return 0;
500 }
501 
502 static void pagetypeinfo_showblockcount_print(struct seq_file *m,
503 					pg_data_t *pgdat, struct zone *zone)
504 {
505 	int mtype;
506 	unsigned long pfn;
507 	unsigned long start_pfn = zone->zone_start_pfn;
508 	unsigned long end_pfn = start_pfn + zone->spanned_pages;
509 	unsigned long count[MIGRATE_TYPES] = { 0, };
510 
511 	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
512 		struct page *page;
513 
514 		if (!pfn_valid(pfn))
515 			continue;
516 
517 		page = pfn_to_page(pfn);
518 		mtype = get_pageblock_migratetype(page);
519 
520 		count[mtype]++;
521 	}
522 
523 	/* Print counts */
524 	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
525 	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
526 		seq_printf(m, "%12lu ", count[mtype]);
527 	seq_putc(m, '\n');
528 }
529 
530 /* Print out the free pages at each order for each migratetype */
531 static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
532 {
533 	int mtype;
534 	pg_data_t *pgdat = (pg_data_t *)arg;
535 
536 	seq_printf(m, "\n%-23s", "Number of blocks type ");
537 	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
538 		seq_printf(m, "%12s ", migratetype_names[mtype]);
539 	seq_putc(m, '\n');
540 	walk_zones_in_node(m, pgdat, pagetypeinfo_showblockcount_print);
541 
542 	return 0;
543 }
544 
545 /*
546  * This prints out statistics in relation to grouping pages by mobility.
547  * It is expensive to collect so do not constantly read the file.
548  */
549 static int pagetypeinfo_show(struct seq_file *m, void *arg)
550 {
551 	pg_data_t *pgdat = (pg_data_t *)arg;
552 
553 	/* check memoryless node */
554 	if (!node_state(pgdat->node_id, N_HIGH_MEMORY))
555 		return 0;
556 
557 	seq_printf(m, "Page block order: %d\n", pageblock_order);
558 	seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
559 	seq_putc(m, '\n');
560 	pagetypeinfo_showfree(m, pgdat);
561 	pagetypeinfo_showblockcount(m, pgdat);
562 
563 	return 0;
564 }
565 
566 const struct seq_operations fragmentation_op = {
567 	.start	= frag_start,
568 	.next	= frag_next,
569 	.stop	= frag_stop,
570 	.show	= frag_show,
571 };
572 
573 const struct seq_operations pagetypeinfo_op = {
574 	.start	= frag_start,
575 	.next	= frag_next,
576 	.stop	= frag_stop,
577 	.show	= pagetypeinfo_show,
578 };
579 
580 #ifdef CONFIG_ZONE_DMA
581 #define TEXT_FOR_DMA(xx) xx "_dma",
582 #else
583 #define TEXT_FOR_DMA(xx)
584 #endif
585 
586 #ifdef CONFIG_ZONE_DMA32
587 #define TEXT_FOR_DMA32(xx) xx "_dma32",
588 #else
589 #define TEXT_FOR_DMA32(xx)
590 #endif
591 
592 #ifdef CONFIG_HIGHMEM
593 #define TEXT_FOR_HIGHMEM(xx) xx "_high",
594 #else
595 #define TEXT_FOR_HIGHMEM(xx)
596 #endif
597 
598 #define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
599 					TEXT_FOR_HIGHMEM(xx) xx "_movable",
600 
601 static const char * const vmstat_text[] = {
602 	/* Zoned VM counters */
603 	"nr_free_pages",
604 	"nr_inactive",
605 	"nr_active",
606 	"nr_anon_pages",
607 	"nr_mapped",
608 	"nr_file_pages",
609 	"nr_dirty",
610 	"nr_writeback",
611 	"nr_slab_reclaimable",
612 	"nr_slab_unreclaimable",
613 	"nr_page_table_pages",
614 	"nr_unstable",
615 	"nr_bounce",
616 	"nr_vmscan_write",
617 	"nr_writeback_temp",
618 
619 #ifdef CONFIG_NUMA
620 	"numa_hit",
621 	"numa_miss",
622 	"numa_foreign",
623 	"numa_interleave",
624 	"numa_local",
625 	"numa_other",
626 #endif
627 
628 #ifdef CONFIG_VM_EVENT_COUNTERS
629 	"pgpgin",
630 	"pgpgout",
631 	"pswpin",
632 	"pswpout",
633 
634 	TEXTS_FOR_ZONES("pgalloc")
635 
636 	"pgfree",
637 	"pgactivate",
638 	"pgdeactivate",
639 
640 	"pgfault",
641 	"pgmajfault",
642 
643 	TEXTS_FOR_ZONES("pgrefill")
644 	TEXTS_FOR_ZONES("pgsteal")
645 	TEXTS_FOR_ZONES("pgscan_kswapd")
646 	TEXTS_FOR_ZONES("pgscan_direct")
647 
648 	"pginodesteal",
649 	"slabs_scanned",
650 	"kswapd_steal",
651 	"kswapd_inodesteal",
652 	"pageoutrun",
653 	"allocstall",
654 
655 	"pgrotated",
656 #ifdef CONFIG_HUGETLB_PAGE
657 	"htlb_buddy_alloc_success",
658 	"htlb_buddy_alloc_fail",
659 #endif
660 #endif
661 };
662 
663 static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
664 							struct zone *zone)
665 {
666 	int i;
667 	seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
668 	seq_printf(m,
669 		   "\n  pages free     %lu"
670 		   "\n        min      %lu"
671 		   "\n        low      %lu"
672 		   "\n        high     %lu"
673 		   "\n        scanned  %lu (a: %lu i: %lu)"
674 		   "\n        spanned  %lu"
675 		   "\n        present  %lu",
676 		   zone_page_state(zone, NR_FREE_PAGES),
677 		   zone->pages_min,
678 		   zone->pages_low,
679 		   zone->pages_high,
680 		   zone->pages_scanned,
681 		   zone->nr_scan_active, zone->nr_scan_inactive,
682 		   zone->spanned_pages,
683 		   zone->present_pages);
684 
685 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
686 		seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
687 				zone_page_state(zone, i));
688 
689 	seq_printf(m,
690 		   "\n        protection: (%lu",
691 		   zone->lowmem_reserve[0]);
692 	for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
693 		seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
694 	seq_printf(m,
695 		   ")"
696 		   "\n  pagesets");
697 	for_each_online_cpu(i) {
698 		struct per_cpu_pageset *pageset;
699 
700 		pageset = zone_pcp(zone, i);
701 		seq_printf(m,
702 			   "\n    cpu: %i"
703 			   "\n              count: %i"
704 			   "\n              high:  %i"
705 			   "\n              batch: %i",
706 			   i,
707 			   pageset->pcp.count,
708 			   pageset->pcp.high,
709 			   pageset->pcp.batch);
710 #ifdef CONFIG_SMP
711 		seq_printf(m, "\n  vm stats threshold: %d",
712 				pageset->stat_threshold);
713 #endif
714 	}
715 	seq_printf(m,
716 		   "\n  all_unreclaimable: %u"
717 		   "\n  prev_priority:     %i"
718 		   "\n  start_pfn:         %lu",
719 			   zone_is_all_unreclaimable(zone),
720 		   zone->prev_priority,
721 		   zone->zone_start_pfn);
722 	seq_putc(m, '\n');
723 }
724 
725 /*
726  * Output information about zones in @pgdat.
727  */
728 static int zoneinfo_show(struct seq_file *m, void *arg)
729 {
730 	pg_data_t *pgdat = (pg_data_t *)arg;
731 	walk_zones_in_node(m, pgdat, zoneinfo_show_print);
732 	return 0;
733 }
734 
735 const struct seq_operations zoneinfo_op = {
736 	.start	= frag_start, /* iterate over all zones. The same as in
737 			       * fragmentation. */
738 	.next	= frag_next,
739 	.stop	= frag_stop,
740 	.show	= zoneinfo_show,
741 };
742 
743 static void *vmstat_start(struct seq_file *m, loff_t *pos)
744 {
745 	unsigned long *v;
746 #ifdef CONFIG_VM_EVENT_COUNTERS
747 	unsigned long *e;
748 #endif
749 	int i;
750 
751 	if (*pos >= ARRAY_SIZE(vmstat_text))
752 		return NULL;
753 
754 #ifdef CONFIG_VM_EVENT_COUNTERS
755 	v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long)
756 			+ sizeof(struct vm_event_state), GFP_KERNEL);
757 #else
758 	v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long),
759 			GFP_KERNEL);
760 #endif
761 	m->private = v;
762 	if (!v)
763 		return ERR_PTR(-ENOMEM);
764 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
765 		v[i] = global_page_state(i);
766 #ifdef CONFIG_VM_EVENT_COUNTERS
767 	e = v + NR_VM_ZONE_STAT_ITEMS;
768 	all_vm_events(e);
769 	e[PGPGIN] /= 2;		/* sectors -> kbytes */
770 	e[PGPGOUT] /= 2;
771 #endif
772 	return v + *pos;
773 }
774 
775 static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
776 {
777 	(*pos)++;
778 	if (*pos >= ARRAY_SIZE(vmstat_text))
779 		return NULL;
780 	return (unsigned long *)m->private + *pos;
781 }
782 
783 static int vmstat_show(struct seq_file *m, void *arg)
784 {
785 	unsigned long *l = arg;
786 	unsigned long off = l - (unsigned long *)m->private;
787 
788 	seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
789 	return 0;
790 }
791 
792 static void vmstat_stop(struct seq_file *m, void *arg)
793 {
794 	kfree(m->private);
795 	m->private = NULL;
796 }
797 
798 const struct seq_operations vmstat_op = {
799 	.start	= vmstat_start,
800 	.next	= vmstat_next,
801 	.stop	= vmstat_stop,
802 	.show	= vmstat_show,
803 };
804 
805 #endif /* CONFIG_PROC_FS */
806 
807 #ifdef CONFIG_SMP
808 static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
809 int sysctl_stat_interval __read_mostly = HZ;
810 
811 static void vmstat_update(struct work_struct *w)
812 {
813 	refresh_cpu_vm_stats(smp_processor_id());
814 	schedule_delayed_work(&__get_cpu_var(vmstat_work),
815 		sysctl_stat_interval);
816 }
817 
818 static void __cpuinit start_cpu_timer(int cpu)
819 {
820 	struct delayed_work *vmstat_work = &per_cpu(vmstat_work, cpu);
821 
822 	INIT_DELAYED_WORK_DEFERRABLE(vmstat_work, vmstat_update);
823 	schedule_delayed_work_on(cpu, vmstat_work, HZ + cpu);
824 }
825 
826 /*
827  * Use the cpu notifier to insure that the thresholds are recalculated
828  * when necessary.
829  */
830 static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
831 		unsigned long action,
832 		void *hcpu)
833 {
834 	long cpu = (long)hcpu;
835 
836 	switch (action) {
837 	case CPU_ONLINE:
838 	case CPU_ONLINE_FROZEN:
839 		start_cpu_timer(cpu);
840 		break;
841 	case CPU_DOWN_PREPARE:
842 	case CPU_DOWN_PREPARE_FROZEN:
843 		cancel_rearming_delayed_work(&per_cpu(vmstat_work, cpu));
844 		per_cpu(vmstat_work, cpu).work.func = NULL;
845 		break;
846 	case CPU_DOWN_FAILED:
847 	case CPU_DOWN_FAILED_FROZEN:
848 		start_cpu_timer(cpu);
849 		break;
850 	case CPU_DEAD:
851 	case CPU_DEAD_FROZEN:
852 		refresh_zone_stat_thresholds();
853 		break;
854 	default:
855 		break;
856 	}
857 	return NOTIFY_OK;
858 }
859 
860 static struct notifier_block __cpuinitdata vmstat_notifier =
861 	{ &vmstat_cpuup_callback, NULL, 0 };
862 
863 static int __init setup_vmstat(void)
864 {
865 	int cpu;
866 
867 	refresh_zone_stat_thresholds();
868 	register_cpu_notifier(&vmstat_notifier);
869 
870 	for_each_online_cpu(cpu)
871 		start_cpu_timer(cpu);
872 	return 0;
873 }
874 module_init(setup_vmstat)
875 #endif
876