[linux.git] / mm / vmstat.c

/*
 *  linux/mm/vmstat.c
 *
 *  Manages VM statistics
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  zoned VM statistics
 *  Copyright (C) 2006 Silicon Graphics, Inc.,
 *		Christoph Lameter <[email protected]>
 */

#include <linux/mm.h>
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/sched.h>

#ifdef CONFIG_VM_EVENT_COUNTERS
DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
EXPORT_PER_CPU_SYMBOL(vm_event_states);

static void sum_vm_events(unsigned long *ret, cpumask_t *cpumask)
{
	int cpu = 0;
	int i;

	memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));

	cpu = first_cpu(*cpumask);
	while (cpu < NR_CPUS) {
		struct vm_event_state *this = &per_cpu(vm_event_states, cpu);

		cpu = next_cpu(cpu, *cpumask);

		if (cpu < NR_CPUS)
			prefetch(&per_cpu(vm_event_states, cpu));


		for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
			ret[i] += this->event[i];
	}
}

/*
 * Accumulate the vm event counters across all CPUs.
 * The result is unavoidably approximate - it can change
 * during and after execution of this function.
*/
void all_vm_events(unsigned long *ret)
{
	sum_vm_events(ret, &cpu_online_map);
}
EXPORT_SYMBOL_GPL(all_vm_events);

#ifdef CONFIG_HOTPLUG
/*
 * Fold the foreign cpu events into our own.
 *
 * This is adding to the events on one processor
 * but keeps the global counts constant.
 */
void vm_events_fold_cpu(int cpu)
{
	struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
	int i;

	for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
		count_vm_events(i, fold_state->event[i]);
		fold_state->event[i] = 0;
	}
}
#endif /* CONFIG_HOTPLUG */

#endif /* CONFIG_VM_EVENT_COUNTERS */

/*
 * Manage combined zone based / global counters
 *
 * vm_stat contains the global counters
 */
atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
EXPORT_SYMBOL(vm_stat);

#ifdef CONFIG_SMP

static int calculate_threshold(struct zone *zone)
{
	int threshold;
	int mem;	/* memory in 128 MB units */

	/*
	 * The threshold scales with the number of processors and the amount
	 * of memory per zone. More memory means that we can defer updates for
	 * longer, more processors could lead to more contention.
 	 * fls() is used to have a cheap way of logarithmic scaling.
	 *
	 * Some sample thresholds:
	 *
	 * Threshold	Processors	(fls)	Zonesize	fls(mem+1)
	 * ------------------------------------------------------------------
	 * 8		1		1	0.9-1 GB	4
	 * 16		2		2	0.9-1 GB	4
	 * 20 		2		2	1-2 GB		5
	 * 24		2		2	2-4 GB		6
	 * 28		2		2	4-8 GB		7
	 * 32		2		2	8-16 GB		8
	 * 4		2		2	<128M		1
	 * 30		4		3	2-4 GB		5
	 * 48		4		3	8-16 GB		8
	 * 32		8		4	1-2 GB		4
	 * 32		8		4	0.9-1GB		4
	 * 10		16		5	<128M		1
	 * 40		16		5	900M		4
	 * 70		64		7	2-4 GB		5
	 * 84		64		7	4-8 GB		6
	 * 108		512		9	4-8 GB		6
	 * 125		1024		10	8-16 GB		8
	 * 125		1024		10	16-32 GB	9
	 */

	mem = zone->present_pages >> (27 - PAGE_SHIFT);

	threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));

	/*
	 * Maximum threshold is 125
	 */
	threshold = min(125, threshold);

	return threshold;
}

/*
 * Refresh the thresholds for each zone.
 */
static void refresh_zone_stat_thresholds(void)
{
	struct zone *zone;
	int cpu;
	int threshold;

	for_each_zone(zone) {

		if (!zone->present_pages)
			continue;

		threshold = calculate_threshold(zone);

		for_each_online_cpu(cpu)
			zone_pcp(zone, cpu)->stat_threshold = threshold;
	}
}

/*
 * For use when we know that interrupts are disabled.
 */
void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
				int delta)
{
	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
	s8 *p = pcp->vm_stat_diff + item;
	long x;

	x = delta + *p;

	if (unlikely(x > pcp->stat_threshold || x < -pcp->stat_threshold)) {
		zone_page_state_add(x, zone, item);
		x = 0;
	}
	*p = x;
}
EXPORT_SYMBOL(__mod_zone_page_state);

/*
 * For an unknown interrupt state
 */
void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
					int delta)
{
	unsigned long flags;

	local_irq_save(flags);
	__mod_zone_page_state(zone, item, delta);
	local_irq_restore(flags);
}
EXPORT_SYMBOL(mod_zone_page_state);

/*
 * Optimized increment and decrement functions.
 *
 * These are only for a single page and therefore can take a struct page *
 * argument instead of struct zone *. This allows the inclusion of the code
 * generated for page_zone(page) into the optimized functions.
 *
 * No overflow check is necessary and therefore the differential can be
 * incremented or decremented in place which may allow the compilers to
 * generate better code.
 * The increment or decrement is known and therefore one boundary check can
 * be omitted.
 *
 * NOTE: These functions are very performance sensitive. Change only
 * with care.
 *
 * Some processors have inc/dec instructions that are atomic vs an interrupt.
 * However, the code must first determine the differential location in a zone
 * based on the processor number and then inc/dec the counter. There is no
 * guarantee without disabling preemption that the processor will not change
 * in between and therefore the atomicity vs. interrupt cannot be exploited
 * in a useful way here.
 */
void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
{
	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
	s8 *p = pcp->vm_stat_diff + item;

	(*p)++;

	if (unlikely(*p > pcp->stat_threshold)) {
		int overstep = pcp->stat_threshold / 2;

		zone_page_state_add(*p + overstep, zone, item);
		*p = -overstep;
	}
}

void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
{
	__inc_zone_state(page_zone(page), item);
}
EXPORT_SYMBOL(__inc_zone_page_state);

void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
{
	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
	s8 *p = pcp->vm_stat_diff + item;

	(*p)--;

	if (unlikely(*p < - pcp->stat_threshold)) {
		int overstep = pcp->stat_threshold / 2;

		zone_page_state_add(*p - overstep, zone, item);
		*p = overstep;
	}
}

void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
{
	__dec_zone_state(page_zone(page), item);
}
EXPORT_SYMBOL(__dec_zone_page_state);

void inc_zone_state(struct zone *zone, enum zone_stat_item item)
{
	unsigned long flags;

	local_irq_save(flags);
	__inc_zone_state(zone, item);
	local_irq_restore(flags);
}

void inc_zone_page_state(struct page *page, enum zone_stat_item item)
{
	unsigned long flags;
	struct zone *zone;

	zone = page_zone(page);
	local_irq_save(flags);
	__inc_zone_state(zone, item);
	local_irq_restore(flags);
}
EXPORT_SYMBOL(inc_zone_page_state);

void dec_zone_page_state(struct page *page, enum zone_stat_item item)
{
	unsigned long flags;

	local_irq_save(flags);
	__dec_zone_page_state(page, item);
	local_irq_restore(flags);
}
EXPORT_SYMBOL(dec_zone_page_state);

/*
 * Update the zone counters for one cpu.
 *
 * Note that refresh_cpu_vm_stats strives to only access
 * node local memory. The per cpu pagesets on remote zones are placed
 * in the memory local to the processor using that pageset. So the
 * loop over all zones will access a series of cachelines local to
 * the processor.
 *
 * The call to zone_page_state_add updates the cachelines with the
 * statistics in the remote zone struct as well as the global cachelines
 * with the global counters. These could cause remote node cache line
 * bouncing and will have to be only done when necessary.
 */
void refresh_cpu_vm_stats(int cpu)
{
	struct zone *zone;
	int i;
	unsigned long flags;

	for_each_zone(zone) {
		struct per_cpu_pageset *p;

		if (!populated_zone(zone))
			continue;

		p = zone_pcp(zone, cpu);

		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
			if (p->vm_stat_diff[i]) {
				local_irq_save(flags);
				zone_page_state_add(p->vm_stat_diff[i],
					zone, i);
				p->vm_stat_diff[i] = 0;
#ifdef CONFIG_NUMA
				/* 3 seconds idle till flush */
				p->expire = 3;
#endif
				local_irq_restore(flags);
			}
#ifdef CONFIG_NUMA
		/*
		 * Deal with draining the remote pageset of this
		 * processor
		 *
		 * Check if there are pages remaining in this pageset
		 * if not then there is nothing to expire.
		 */
		if (!p->expire || (!p->pcp[0].count && !p->pcp[1].count))
			continue;

		/*
		 * We never drain zones local to this processor.
		 */
		if (zone_to_nid(zone) == numa_node_id()) {
			p->expire = 0;
			continue;
		}

		p->expire--;
		if (p->expire)
			continue;

		if (p->pcp[0].count)
			drain_zone_pages(zone, p->pcp + 0);

		if (p->pcp[1].count)
			drain_zone_pages(zone, p->pcp + 1);
#endif
	}
}

static void __refresh_cpu_vm_stats(void *dummy)
{
	refresh_cpu_vm_stats(smp_processor_id());
}

/*
 * Consolidate all counters.
 *
 * Note that the result is less inaccurate but still inaccurate
 * if concurrent processes are allowed to run.
 */
void refresh_vm_stats(void)
{
	on_each_cpu(__refresh_cpu_vm_stats, NULL, 0, 1);
}
EXPORT_SYMBOL(refresh_vm_stats);

#endif

#ifdef CONFIG_NUMA
/*
 * zonelist = the list of zones passed to the allocator
 * z 	    = the zone from which the allocation occurred.
 *
 * Must be called with interrupts disabled.
 */
void zone_statistics(struct zonelist *zonelist, struct zone *z)
{
	if (z->zone_pgdat == zonelist->zones[0]->zone_pgdat) {
		__inc_zone_state(z, NUMA_HIT);
	} else {
		__inc_zone_state(z, NUMA_MISS);
		__inc_zone_state(zonelist->zones[0], NUMA_FOREIGN);
	}
	if (z->node == numa_node_id())
		__inc_zone_state(z, NUMA_LOCAL);
	else
		__inc_zone_state(z, NUMA_OTHER);
}
#endif

#ifdef CONFIG_PROC_FS

#include <linux/seq_file.h>

static void *frag_start(struct seq_file *m, loff_t *pos)
{
	pg_data_t *pgdat;
	loff_t node = *pos;
	for (pgdat = first_online_pgdat();
	     pgdat && node;
	     pgdat = next_online_pgdat(pgdat))
		--node;

	return pgdat;
}

static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
{
	pg_data_t *pgdat = (pg_data_t *)arg;

	(*pos)++;
	return next_online_pgdat(pgdat);
}

static void frag_stop(struct seq_file *m, void *arg)
{
}

/*
 * This walks the free areas for each zone.
 */
static int frag_show(struct seq_file *m, void *arg)
{
	pg_data_t *pgdat = (pg_data_t *)arg;
	struct zone *zone;
	struct zone *node_zones = pgdat->node_zones;
	unsigned long flags;
	int order;

	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
		if (!populated_zone(zone))
			continue;

		spin_lock_irqsave(&zone->lock, flags);
		seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
		for (order = 0; order < MAX_ORDER; ++order)
			seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
		spin_unlock_irqrestore(&zone->lock, flags);
		seq_putc(m, '\n');
	}
	return 0;
}

const struct seq_operations fragmentation_op = {
	.start	= frag_start,
	.next	= frag_next,
	.stop	= frag_stop,
	.show	= frag_show,
};

#ifdef CONFIG_ZONE_DMA
#define TEXT_FOR_DMA(xx) xx "_dma",
#else
#define TEXT_FOR_DMA(xx)
#endif

#ifdef CONFIG_ZONE_DMA32
#define TEXT_FOR_DMA32(xx) xx "_dma32",
#else
#define TEXT_FOR_DMA32(xx)
#endif

#ifdef CONFIG_HIGHMEM
#define TEXT_FOR_HIGHMEM(xx) xx "_high",
#else
#define TEXT_FOR_HIGHMEM(xx)
#endif

#define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
					TEXT_FOR_HIGHMEM(xx) xx "_movable",

static const char * const vmstat_text[] = {
	/* Zoned VM counters */
	"nr_free_pages",
	"nr_inactive",
	"nr_active",
	"nr_anon_pages",
	"nr_mapped",
	"nr_file_pages",
	"nr_dirty",
	"nr_writeback",
	"nr_slab_reclaimable",
	"nr_slab_unreclaimable",
	"nr_page_table_pages",
	"nr_unstable",
	"nr_bounce",
	"nr_vmscan_write",

#ifdef CONFIG_NUMA
	"numa_hit",
	"numa_miss",
	"numa_foreign",
	"numa_interleave",
	"numa_local",
	"numa_other",
#endif

#ifdef CONFIG_VM_EVENT_COUNTERS
	"pgpgin",
	"pgpgout",
	"pswpin",
	"pswpout",

	TEXTS_FOR_ZONES("pgalloc")

	"pgfree",
	"pgactivate",
	"pgdeactivate",

	"pgfault",
	"pgmajfault",

	TEXTS_FOR_ZONES("pgrefill")
	TEXTS_FOR_ZONES("pgsteal")
	TEXTS_FOR_ZONES("pgscan_kswapd")
	TEXTS_FOR_ZONES("pgscan_direct")

	"pginodesteal",
	"slabs_scanned",
	"kswapd_steal",
	"kswapd_inodesteal",
	"pageoutrun",
	"allocstall",

	"pgrotated",
#endif
};

/*
 * Output information about zones in @pgdat.
 */
static int zoneinfo_show(struct seq_file *m, void *arg)
{
	pg_data_t *pgdat = arg;
	struct zone *zone;
	struct zone *node_zones = pgdat->node_zones;
	unsigned long flags;

	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; zone++) {
		int i;

		if (!populated_zone(zone))
			continue;

		spin_lock_irqsave(&zone->lock, flags);
		seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
		seq_printf(m,
			   "\n  pages free     %lu"
			   "\n        min      %lu"
			   "\n        low      %lu"
			   "\n        high     %lu"
			   "\n        scanned  %lu (a: %lu i: %lu)"
			   "\n        spanned  %lu"
			   "\n        present  %lu",
			   zone_page_state(zone, NR_FREE_PAGES),
			   zone->pages_min,
			   zone->pages_low,
			   zone->pages_high,
			   zone->pages_scanned,
			   zone->nr_scan_active, zone->nr_scan_inactive,
			   zone->spanned_pages,
			   zone->present_pages);

		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
			seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
					zone_page_state(zone, i));

		seq_printf(m,
			   "\n        protection: (%lu",
			   zone->lowmem_reserve[0]);
		for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
			seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
		seq_printf(m,
			   ")"
			   "\n  pagesets");
		for_each_online_cpu(i) {
			struct per_cpu_pageset *pageset;
			int j;

			pageset = zone_pcp(zone, i);
			for (j = 0; j < ARRAY_SIZE(pageset->pcp); j++) {
				seq_printf(m,
					   "\n    cpu: %i pcp: %i"
					   "\n              count: %i"
					   "\n              high:  %i"
					   "\n              batch: %i",
					   i, j,
					   pageset->pcp[j].count,
					   pageset->pcp[j].high,
					   pageset->pcp[j].batch);
			}
#ifdef CONFIG_SMP
			seq_printf(m, "\n  vm stats threshold: %d",
					pageset->stat_threshold);
#endif
		}
		seq_printf(m,
			   "\n  all_unreclaimable: %u"
			   "\n  prev_priority:     %i"
			   "\n  start_pfn:         %lu",
			   zone->all_unreclaimable,
			   zone->prev_priority,
			   zone->zone_start_pfn);
		spin_unlock_irqrestore(&zone->lock, flags);
		seq_putc(m, '\n');
	}
	return 0;
}

const struct seq_operations zoneinfo_op = {
	.start	= frag_start, /* iterate over all zones. The same as in
			       * fragmentation. */
	.next	= frag_next,
	.stop	= frag_stop,
	.show	= zoneinfo_show,
};

static void *vmstat_start(struct seq_file *m, loff_t *pos)
{
	unsigned long *v;
#ifdef CONFIG_VM_EVENT_COUNTERS
	unsigned long *e;
#endif
	int i;

	if (*pos >= ARRAY_SIZE(vmstat_text))
		return NULL;

#ifdef CONFIG_VM_EVENT_COUNTERS
	v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long)
			+ sizeof(struct vm_event_state), GFP_KERNEL);
#else
	v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long),
			GFP_KERNEL);
#endif
	m->private = v;
	if (!v)
		return ERR_PTR(-ENOMEM);
	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
		v[i] = global_page_state(i);
#ifdef CONFIG_VM_EVENT_COUNTERS
	e = v + NR_VM_ZONE_STAT_ITEMS;
	all_vm_events(e);
	e[PGPGIN] /= 2;		/* sectors -> kbytes */
	e[PGPGOUT] /= 2;
#endif
	return v + *pos;
}

static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
{
	(*pos)++;
	if (*pos >= ARRAY_SIZE(vmstat_text))
		return NULL;
	return (unsigned long *)m->private + *pos;
}

static int vmstat_show(struct seq_file *m, void *arg)
{
	unsigned long *l = arg;
	unsigned long off = l - (unsigned long *)m->private;

	seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
	return 0;
}

static void vmstat_stop(struct seq_file *m, void *arg)
{
	kfree(m->private);
	m->private = NULL;
}

const struct seq_operations vmstat_op = {
	.start	= vmstat_start,
	.next	= vmstat_next,
	.stop	= vmstat_stop,
	.show	= vmstat_show,
};

#endif /* CONFIG_PROC_FS */

#ifdef CONFIG_SMP
static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
int sysctl_stat_interval __read_mostly = HZ;

static void vmstat_update(struct work_struct *w)
{
	refresh_cpu_vm_stats(smp_processor_id());
	schedule_delayed_work(&__get_cpu_var(vmstat_work),
		sysctl_stat_interval);
}

static void __devinit start_cpu_timer(int cpu)
{
	struct delayed_work *vmstat_work = &per_cpu(vmstat_work, cpu);

	INIT_DELAYED_WORK_DEFERRABLE(vmstat_work, vmstat_update);
	schedule_delayed_work_on(cpu, vmstat_work, HZ + cpu);
}

/*
 * Use the cpu notifier to insure that the thresholds are recalculated
 * when necessary.
 */
static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
		unsigned long action,
		void *hcpu)
{
	long cpu = (long)hcpu;

	switch (action) {
	case CPU_ONLINE:
	case CPU_ONLINE_FROZEN:
		start_cpu_timer(cpu);
		break;
	case CPU_DOWN_PREPARE:
	case CPU_DOWN_PREPARE_FROZEN:
		cancel_rearming_delayed_work(&per_cpu(vmstat_work, cpu));
		per_cpu(vmstat_work, cpu).work.func = NULL;
		break;
	case CPU_DOWN_FAILED:
	case CPU_DOWN_FAILED_FROZEN:
		start_cpu_timer(cpu);
		break;
	case CPU_DEAD:
	case CPU_DEAD_FROZEN:
		refresh_zone_stat_thresholds();
		break;
	default:
		break;
	}
	return NOTIFY_OK;
}

static struct notifier_block __cpuinitdata vmstat_notifier =
	{ &vmstat_cpuup_callback, NULL, 0 };

int __init setup_vmstat(void)
{
	int cpu;

	refresh_zone_stat_thresholds();
	register_cpu_notifier(&vmstat_notifier);

	for_each_online_cpu(cpu)
		start_cpu_timer(cpu);
	return 0;
}
module_init(setup_vmstat)
#endif
Commit	Line	Data
f6ac2354 CL	1	/*
	2	* linux/mm/vmstat.c
	3	*
	4	* Manages VM statistics
	5	* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
2244b95a CL	6	*
	7	* zoned VM statistics
	8	* Copyright (C) 2006 Silicon Graphics, Inc.,
	9	* Christoph Lameter <[email protected]>
f6ac2354 CL	10	*/
f6ac2354 CL	11
f6ac2354	12	#include <linux/mm.h>
2244b95a	13	#include <linux/module.h>
df9ecaba	14	#include <linux/cpu.h>
e8edc6e0	15	#include <linux/sched.h>
f6ac2354	16
f8891e5e CL	17	#ifdef CONFIG_VM_EVENT_COUNTERS
	18	DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
	19	EXPORT_PER_CPU_SYMBOL(vm_event_states);
	20
	21	static void sum_vm_events(unsigned long ret, cpumask_t cpumask)
	22	{
	23	int cpu = 0;
	24	int i;
	25
	26	memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
	27
	28	cpu = first_cpu(*cpumask);
	29	while (cpu < NR_CPUS) {
	30	struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
	31
	32	cpu = next_cpu(cpu, *cpumask);
	33
	34	if (cpu < NR_CPUS)
	35	prefetch(&per_cpu(vm_event_states, cpu));
	36
	37
	38	for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
	39	ret[i] += this->event[i];
	40	}
	41	}
	42
	43	/*
	44	* Accumulate the vm event counters across all CPUs.
	45	* The result is unavoidably approximate - it can change
	46	* during and after execution of this function.
	47	*/
	48	void all_vm_events(unsigned long *ret)
	49	{
	50	sum_vm_events(ret, &cpu_online_map);
	51	}
32dd66fc	52	EXPORT_SYMBOL_GPL(all_vm_events);
f8891e5e CL	53
	54	#ifdef CONFIG_HOTPLUG
	55	/*
	56	* Fold the foreign cpu events into our own.
	57	*
	58	* This is adding to the events on one processor
	59	* but keeps the global counts constant.
	60	*/
	61	void vm_events_fold_cpu(int cpu)
	62	{
	63	struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
	64	int i;
	65
	66	for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
	67	count_vm_events(i, fold_state->event[i]);
	68	fold_state->event[i] = 0;
	69	}
	70	}
	71	#endif /* CONFIG_HOTPLUG */
	72
	73	#endif /* CONFIG_VM_EVENT_COUNTERS */
	74
2244b95a CL	75	/*
	76	* Manage combined zone based / global counters
	77	*
	78	* vm_stat contains the global counters
	79	*/
	80	atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
	81	EXPORT_SYMBOL(vm_stat);
	82
	83	#ifdef CONFIG_SMP
	84
df9ecaba CL	85	static int calculate_threshold(struct zone *zone)
	86	{
	87	int threshold;
	88	int mem; /* memory in 128 MB units */
	89
	90	/*
	91	* The threshold scales with the number of processors and the amount
	92	* of memory per zone. More memory means that we can defer updates for
	93	* longer, more processors could lead to more contention.
	94	* fls() is used to have a cheap way of logarithmic scaling.
	95	*
	96	* Some sample thresholds:
	97	*
	98	* Threshold Processors (fls) Zonesize fls(mem+1)
	99	* ------------------------------------------------------------------
	100	* 8 1 1 0.9-1 GB 4
	101	* 16 2 2 0.9-1 GB 4
	102	* 20 2 2 1-2 GB 5
	103	* 24 2 2 2-4 GB 6
	104	* 28 2 2 4-8 GB 7
	105	* 32 2 2 8-16 GB 8
	106	* 4 2 2 <128M 1
	107	* 30 4 3 2-4 GB 5
	108	* 48 4 3 8-16 GB 8
	109	* 32 8 4 1-2 GB 4
	110	* 32 8 4 0.9-1GB 4
	111	* 10 16 5 <128M 1
	112	* 40 16 5 900M 4
	113	* 70 64 7 2-4 GB 5
	114	* 84 64 7 4-8 GB 6
	115	* 108 512 9 4-8 GB 6
	116	* 125 1024 10 8-16 GB 8
	117	* 125 1024 10 16-32 GB 9
	118	*/
	119
	120	mem = zone->present_pages >> (27 - PAGE_SHIFT);
	121
	122	threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
	123
	124	/*
	125	* Maximum threshold is 125
	126	*/
	127	threshold = min(125, threshold);
	128
	129	return threshold;
	130	}
2244b95a CL	131
2244b95a CL	132	/*
df9ecaba	133	* Refresh the thresholds for each zone.
2244b95a	134	*/
df9ecaba	135	static void refresh_zone_stat_thresholds(void)
2244b95a	136	{
df9ecaba CL	137	struct zone *zone;
	138	int cpu;
	139	int threshold;
	140
	141	for_each_zone(zone) {
	142
	143	if (!zone->present_pages)
	144	continue;
	145
	146	threshold = calculate_threshold(zone);
	147
	148	for_each_online_cpu(cpu)
	149	zone_pcp(zone, cpu)->stat_threshold = threshold;
	150	}
2244b95a CL	151	}
	152
	153	/*
	154	* For use when we know that interrupts are disabled.
	155	*/
	156	void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
	157	int delta)
	158	{
df9ecaba CL	159	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
df9ecaba CL	160	s8 *p = pcp->vm_stat_diff + item;
2244b95a CL	161	long x;
2244b95a CL	162
2244b95a CL	163	x = delta + *p;
2244b95a CL	164
df9ecaba	165	if (unlikely(x > pcp->stat_threshold \|\| x < -pcp->stat_threshold)) {
2244b95a CL	166	zone_page_state_add(x, zone, item);
	167	x = 0;
	168	}
2244b95a CL	169	*p = x;
	170	}
	171	EXPORT_SYMBOL(__mod_zone_page_state);
	172
	173	/*
	174	* For an unknown interrupt state
	175	*/
	176	void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
	177	int delta)
	178	{
	179	unsigned long flags;
	180
	181	local_irq_save(flags);
	182	__mod_zone_page_state(zone, item, delta);
	183	local_irq_restore(flags);
	184	}
	185	EXPORT_SYMBOL(mod_zone_page_state);
	186
	187	/*
	188	* Optimized increment and decrement functions.
	189	*
	190	* These are only for a single page and therefore can take a struct page *
	191	* argument instead of struct zone *. This allows the inclusion of the code
	192	* generated for page_zone(page) into the optimized functions.
	193	*
	194	* No overflow check is necessary and therefore the differential can be
	195	* incremented or decremented in place which may allow the compilers to
	196	* generate better code.
2244b95a CL	197	* The increment or decrement is known and therefore one boundary check can
	198	* be omitted.
	199	*
df9ecaba CL	200	* NOTE: These functions are very performance sensitive. Change only
	201	* with care.
	202	*
2244b95a CL	203	* Some processors have inc/dec instructions that are atomic vs an interrupt.
	204	* However, the code must first determine the differential location in a zone
	205	* based on the processor number and then inc/dec the counter. There is no
	206	* guarantee without disabling preemption that the processor will not change
	207	* in between and therefore the atomicity vs. interrupt cannot be exploited
	208	* in a useful way here.
	209	*/
c8785385	210	void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
2244b95a	211	{
df9ecaba CL	212	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
df9ecaba CL	213	s8 *p = pcp->vm_stat_diff + item;
2244b95a CL	214
	215	(*p)++;
	216
df9ecaba CL	217	if (unlikely(*p > pcp->stat_threshold)) {
	218	int overstep = pcp->stat_threshold / 2;
	219
	220	zone_page_state_add(*p + overstep, zone, item);
	221	*p = -overstep;
2244b95a CL	222	}
2244b95a CL	223	}
ca889e6c CL	224
	225	void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
	226	{
	227	__inc_zone_state(page_zone(page), item);
	228	}
2244b95a CL	229	EXPORT_SYMBOL(__inc_zone_page_state);
2244b95a CL	230
c8785385	231	void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
2244b95a	232	{
df9ecaba CL	233	struct per_cpu_pageset *pcp = zone_pcp(zone, smp_processor_id());
df9ecaba CL	234	s8 *p = pcp->vm_stat_diff + item;
2244b95a CL	235
	236	(*p)--;
	237
df9ecaba CL	238	if (unlikely(*p < - pcp->stat_threshold)) {
	239	int overstep = pcp->stat_threshold / 2;
	240
	241	zone_page_state_add(*p - overstep, zone, item);
	242	*p = overstep;
2244b95a CL	243	}
2244b95a CL	244	}
c8785385 CL	245
	246	void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
	247	{
	248	__dec_zone_state(page_zone(page), item);
	249	}
2244b95a CL	250	EXPORT_SYMBOL(__dec_zone_page_state);
2244b95a CL	251
ca889e6c CL	252	void inc_zone_state(struct zone *zone, enum zone_stat_item item)
	253	{
	254	unsigned long flags;
	255
	256	local_irq_save(flags);
	257	__inc_zone_state(zone, item);
	258	local_irq_restore(flags);
	259	}
	260
2244b95a CL	261	void inc_zone_page_state(struct page *page, enum zone_stat_item item)
	262	{
	263	unsigned long flags;
	264	struct zone *zone;
2244b95a CL	265
	266	zone = page_zone(page);
	267	local_irq_save(flags);
ca889e6c	268	__inc_zone_state(zone, item);
2244b95a CL	269	local_irq_restore(flags);
	270	}
	271	EXPORT_SYMBOL(inc_zone_page_state);
	272
	273	void dec_zone_page_state(struct page *page, enum zone_stat_item item)
	274	{
	275	unsigned long flags;
2244b95a	276
2244b95a	277	local_irq_save(flags);
a302eb4e	278	__dec_zone_page_state(page, item);
2244b95a CL	279	local_irq_restore(flags);
	280	}
	281	EXPORT_SYMBOL(dec_zone_page_state);
	282
	283	/*
	284	* Update the zone counters for one cpu.
4037d452 CL	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.
2244b95a CL	296	*/
	297	void refresh_cpu_vm_stats(int cpu)
	298	{
	299	struct zone *zone;
	300	int i;
	301	unsigned long flags;
	302
	303	for_each_zone(zone) {
4037d452	304	struct per_cpu_pageset *p;
2244b95a	305
39bbcb8f CL	306	if (!populated_zone(zone))
	307	continue;
	308
4037d452	309	p = zone_pcp(zone, cpu);
2244b95a CL	310
2244b95a CL	311	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
4037d452	312	if (p->vm_stat_diff[i]) {
2244b95a	313	local_irq_save(flags);
4037d452	314	zone_page_state_add(p->vm_stat_diff[i],
2244b95a	315	zone, i);
4037d452 CL	316	p->vm_stat_diff[i] = 0;
	317	#ifdef CONFIG_NUMA
	318	/* 3 seconds idle till flush */
	319	p->expire = 3;
	320	#endif
2244b95a CL	321	local_irq_restore(flags);
2244b95a CL	322	}
4037d452 CL	323	#ifdef CONFIG_NUMA
	324	/*
	325	* Deal with draining the remote pageset of this
	326	* processor
	327	*
	328	* Check if there are pages remaining in this pageset
	329	* if not then there is nothing to expire.
	330	*/
	331	if (!p->expire \|\| (!p->pcp[0].count && !p->pcp[1].count))
	332	continue;
	333
	334	/*
	335	* We never drain zones local to this processor.
	336	*/
	337	if (zone_to_nid(zone) == numa_node_id()) {
	338	p->expire = 0;
	339	continue;
	340	}
	341
	342	p->expire--;
	343	if (p->expire)
	344	continue;
	345
	346	if (p->pcp[0].count)
	347	drain_zone_pages(zone, p->pcp + 0);
	348
	349	if (p->pcp[1].count)
	350	drain_zone_pages(zone, p->pcp + 1);
	351	#endif
2244b95a CL	352	}
	353	}
	354
	355	static void __refresh_cpu_vm_stats(void *dummy)
	356	{
	357	refresh_cpu_vm_stats(smp_processor_id());
	358	}
	359
	360	/*
	361	* Consolidate all counters.
	362	*
	363	* Note that the result is less inaccurate but still inaccurate
	364	* if concurrent processes are allowed to run.
	365	*/
	366	void refresh_vm_stats(void)
	367	{
	368	on_each_cpu(__refresh_cpu_vm_stats, NULL, 0, 1);
	369	}
	370	EXPORT_SYMBOL(refresh_vm_stats);
	371
	372	#endif
	373
ca889e6c CL	374	#ifdef CONFIG_NUMA
	375	/*
	376	* zonelist = the list of zones passed to the allocator
	377	* z = the zone from which the allocation occurred.
	378	*
	379	* Must be called with interrupts disabled.
	380	*/
	381	void zone_statistics(struct zonelist zonelist, struct zone z)
	382	{
	383	if (z->zone_pgdat == zonelist->zones[0]->zone_pgdat) {
	384	__inc_zone_state(z, NUMA_HIT);
	385	} else {
	386	__inc_zone_state(z, NUMA_MISS);
	387	__inc_zone_state(zonelist->zones[0], NUMA_FOREIGN);
	388	}
5d292343	389	if (z->node == numa_node_id())
ca889e6c CL	390	__inc_zone_state(z, NUMA_LOCAL);
	391	else
	392	__inc_zone_state(z, NUMA_OTHER);
	393	}
	394	#endif
	395
f6ac2354 CL	396	#ifdef CONFIG_PROC_FS
	397
	398	#include <linux/seq_file.h>
	399
	400	static void frag_start(struct seq_file m, loff_t *pos)
	401	{
	402	pg_data_t *pgdat;
	403	loff_t node = *pos;
	404	for (pgdat = first_online_pgdat();
	405	pgdat && node;
	406	pgdat = next_online_pgdat(pgdat))
	407	--node;
	408
	409	return pgdat;
	410	}
	411
	412	static void frag_next(struct seq_file m, void arg, loff_t pos)
	413	{
	414	pg_data_t pgdat = (pg_data_t )arg;
	415
	416	(*pos)++;
	417	return next_online_pgdat(pgdat);
	418	}
	419
	420	static void frag_stop(struct seq_file m, void arg)
	421	{
	422	}
	423
	424	/*
	425	* This walks the free areas for each zone.
	426	*/
	427	static int frag_show(struct seq_file m, void arg)
	428	{
	429	pg_data_t pgdat = (pg_data_t )arg;
	430	struct zone *zone;
	431	struct zone *node_zones = pgdat->node_zones;
	432	unsigned long flags;
	433	int order;
	434
	435	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
	436	if (!populated_zone(zone))
	437	continue;
	438
	439	spin_lock_irqsave(&zone->lock, flags);
	440	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
	441	for (order = 0; order < MAX_ORDER; ++order)
	442	seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
	443	spin_unlock_irqrestore(&zone->lock, flags);
	444	seq_putc(m, '\n');
	445	}
	446	return 0;
	447	}
	448
15ad7cdc	449	const struct seq_operations fragmentation_op = {
f6ac2354 CL	450	.start = frag_start,
	451	.next = frag_next,
	452	.stop = frag_stop,
	453	.show = frag_show,
	454	};
	455
4b51d669 CL	456	#ifdef CONFIG_ZONE_DMA
	457	#define TEXT_FOR_DMA(xx) xx "_dma",
	458	#else
	459	#define TEXT_FOR_DMA(xx)
	460	#endif
	461
27bf71c2 CL	462	#ifdef CONFIG_ZONE_DMA32
	463	#define TEXT_FOR_DMA32(xx) xx "_dma32",
	464	#else
	465	#define TEXT_FOR_DMA32(xx)
	466	#endif
	467
	468	#ifdef CONFIG_HIGHMEM
	469	#define TEXT_FOR_HIGHMEM(xx) xx "_high",
	470	#else
	471	#define TEXT_FOR_HIGHMEM(xx)
	472	#endif
	473
4b51d669	474	#define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
2a1e274a	475	TEXT_FOR_HIGHMEM(xx) xx "_movable",
27bf71c2	476
15ad7cdc	477	static const char * const vmstat_text[] = {
2244b95a	478	/* Zoned VM counters */
d23ad423	479	"nr_free_pages",
c8785385	480	"nr_inactive",
23c1fb52	481	"nr_active",
f3dbd344	482	"nr_anon_pages",
65ba55f5	483	"nr_mapped",
347ce434	484	"nr_file_pages",
51ed4491 CL	485	"nr_dirty",
51ed4491 CL	486	"nr_writeback",
972d1a7b CL	487	"nr_slab_reclaimable",
972d1a7b CL	488	"nr_slab_unreclaimable",
df849a15	489	"nr_page_table_pages",
f6ac2354	490	"nr_unstable",
d2c5e30c	491	"nr_bounce",
e129b5c2	492	"nr_vmscan_write",
f6ac2354	493
ca889e6c CL	494	#ifdef CONFIG_NUMA
	495	"numa_hit",
	496	"numa_miss",
	497	"numa_foreign",
	498	"numa_interleave",
	499	"numa_local",
	500	"numa_other",
	501	#endif
	502
f8891e5e	503	#ifdef CONFIG_VM_EVENT_COUNTERS
f6ac2354 CL	504	"pgpgin",
	505	"pgpgout",
	506	"pswpin",
	507	"pswpout",
	508
27bf71c2	509	TEXTS_FOR_ZONES("pgalloc")
f6ac2354 CL	510
	511	"pgfree",
	512	"pgactivate",
	513	"pgdeactivate",
	514
	515	"pgfault",
	516	"pgmajfault",
	517
27bf71c2 CL	518	TEXTS_FOR_ZONES("pgrefill")
	519	TEXTS_FOR_ZONES("pgsteal")
	520	TEXTS_FOR_ZONES("pgscan_kswapd")
	521	TEXTS_FOR_ZONES("pgscan_direct")
f6ac2354 CL	522
	523	"pginodesteal",
	524	"slabs_scanned",
	525	"kswapd_steal",
	526	"kswapd_inodesteal",
	527	"pageoutrun",
	528	"allocstall",
	529
	530	"pgrotated",
f8891e5e	531	#endif
f6ac2354 CL	532	};
	533
	534	/*
	535	* Output information about zones in @pgdat.
	536	*/
	537	static int zoneinfo_show(struct seq_file m, void arg)
	538	{
	539	pg_data_t *pgdat = arg;
	540	struct zone *zone;
	541	struct zone *node_zones = pgdat->node_zones;
	542	unsigned long flags;
	543
	544	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; zone++) {
	545	int i;
	546
	547	if (!populated_zone(zone))
	548	continue;
	549
	550	spin_lock_irqsave(&zone->lock, flags);
	551	seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
	552	seq_printf(m,
	553	"\n pages free %lu"
	554	"\n min %lu"
	555	"\n low %lu"
	556	"\n high %lu"
f6ac2354 CL	557	"\n scanned %lu (a: %lu i: %lu)"
	558	"\n spanned %lu"
	559	"\n present %lu",
d23ad423	560	zone_page_state(zone, NR_FREE_PAGES),
f6ac2354 CL	561	zone->pages_min,
	562	zone->pages_low,
	563	zone->pages_high,
f6ac2354 CL	564	zone->pages_scanned,
	565	zone->nr_scan_active, zone->nr_scan_inactive,
	566	zone->spanned_pages,
	567	zone->present_pages);
2244b95a CL	568
	569	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
	570	seq_printf(m, "\n %-12s %lu", vmstat_text[i],
	571	zone_page_state(zone, i));
	572
f6ac2354 CL	573	seq_printf(m,
	574	"\n protection: (%lu",
	575	zone->lowmem_reserve[0]);
	576	for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
	577	seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
	578	seq_printf(m,
	579	")"
	580	"\n pagesets");
	581	for_each_online_cpu(i) {
	582	struct per_cpu_pageset *pageset;
	583	int j;
	584
	585	pageset = zone_pcp(zone, i);
f6ac2354 CL	586	for (j = 0; j < ARRAY_SIZE(pageset->pcp); j++) {
	587	seq_printf(m,
	588	"\n cpu: %i pcp: %i"
	589	"\n count: %i"
	590	"\n high: %i"
	591	"\n batch: %i",
	592	i, j,
	593	pageset->pcp[j].count,
	594	pageset->pcp[j].high,
	595	pageset->pcp[j].batch);
	596	}
df9ecaba CL	597	#ifdef CONFIG_SMP
	598	seq_printf(m, "\n vm stats threshold: %d",
	599	pageset->stat_threshold);
	600	#endif
f6ac2354 CL	601	}
	602	seq_printf(m,
	603	"\n all_unreclaimable: %u"
	604	"\n prev_priority: %i"
f6ac2354 CL	605	"\n start_pfn: %lu",
	606	zone->all_unreclaimable,
	607	zone->prev_priority,
f6ac2354 CL	608	zone->zone_start_pfn);
	609	spin_unlock_irqrestore(&zone->lock, flags);
	610	seq_putc(m, '\n');
	611	}
	612	return 0;
	613	}
	614
15ad7cdc	615	const struct seq_operations zoneinfo_op = {
f6ac2354 CL	616	.start = frag_start, /* iterate over all zones. The same as in
	617	* fragmentation. */
	618	.next = frag_next,
	619	.stop = frag_stop,
	620	.show = zoneinfo_show,
	621	};
	622
	623	static void vmstat_start(struct seq_file m, loff_t *pos)
	624	{
2244b95a	625	unsigned long *v;
f8891e5e CL	626	#ifdef CONFIG_VM_EVENT_COUNTERS
	627	unsigned long *e;
	628	#endif
2244b95a	629	int i;
f6ac2354 CL	630
	631	if (*pos >= ARRAY_SIZE(vmstat_text))
	632	return NULL;
	633
f8891e5e	634	#ifdef CONFIG_VM_EVENT_COUNTERS
2244b95a	635	v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long)
f8891e5e CL	636	+ sizeof(struct vm_event_state), GFP_KERNEL);
	637	#else
	638	v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long),
	639	GFP_KERNEL);
	640	#endif
2244b95a CL	641	m->private = v;
2244b95a CL	642	if (!v)
f6ac2354	643	return ERR_PTR(-ENOMEM);
2244b95a CL	644	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
2244b95a CL	645	v[i] = global_page_state(i);
f8891e5e CL	646	#ifdef CONFIG_VM_EVENT_COUNTERS
	647	e = v + NR_VM_ZONE_STAT_ITEMS;
	648	all_vm_events(e);
	649	e[PGPGIN] /= 2; /* sectors -> kbytes */
	650	e[PGPGOUT] /= 2;
	651	#endif
2244b95a	652	return v + *pos;
f6ac2354 CL	653	}
	654
	655	static void vmstat_next(struct seq_file m, void arg, loff_t pos)
	656	{
	657	(*pos)++;
	658	if (*pos >= ARRAY_SIZE(vmstat_text))
	659	return NULL;
	660	return (unsigned long )m->private + pos;
	661	}
	662
	663	static int vmstat_show(struct seq_file m, void arg)
	664	{
	665	unsigned long *l = arg;
	666	unsigned long off = l - (unsigned long *)m->private;
	667
	668	seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
	669	return 0;
	670	}
	671
	672	static void vmstat_stop(struct seq_file m, void arg)
	673	{
	674	kfree(m->private);
	675	m->private = NULL;
	676	}
	677
15ad7cdc	678	const struct seq_operations vmstat_op = {
f6ac2354 CL	679	.start = vmstat_start,
	680	.next = vmstat_next,
	681	.stop = vmstat_stop,
	682	.show = vmstat_show,
	683	};
	684
	685	#endif /* CONFIG_PROC_FS */
	686
df9ecaba	687	#ifdef CONFIG_SMP
d1187ed2	688	static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
77461ab3	689	int sysctl_stat_interval __read_mostly = HZ;
d1187ed2 CL	690
	691	static void vmstat_update(struct work_struct *w)
	692	{
	693	refresh_cpu_vm_stats(smp_processor_id());
77461ab3 CL	694	schedule_delayed_work(&__get_cpu_var(vmstat_work),
77461ab3 CL	695	sysctl_stat_interval);
d1187ed2 CL	696	}
	697
	698	static void __devinit start_cpu_timer(int cpu)
	699	{
	700	struct delayed_work *vmstat_work = &per_cpu(vmstat_work, cpu);
	701
39bf6270	702	INIT_DELAYED_WORK_DEFERRABLE(vmstat_work, vmstat_update);
d1187ed2 CL	703	schedule_delayed_work_on(cpu, vmstat_work, HZ + cpu);
	704	}
	705
df9ecaba CL	706	/*
	707	* Use the cpu notifier to insure that the thresholds are recalculated
	708	* when necessary.
	709	*/
	710	static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
	711	unsigned long action,
	712	void *hcpu)
	713	{
d1187ed2 CL	714	long cpu = (long)hcpu;
d1187ed2 CL	715
df9ecaba	716	switch (action) {
d1187ed2 CL	717	case CPU_ONLINE:
	718	case CPU_ONLINE_FROZEN:
	719	start_cpu_timer(cpu);
	720	break;
	721	case CPU_DOWN_PREPARE:
	722	case CPU_DOWN_PREPARE_FROZEN:
	723	cancel_rearming_delayed_work(&per_cpu(vmstat_work, cpu));
	724	per_cpu(vmstat_work, cpu).work.func = NULL;
	725	break;
	726	case CPU_DOWN_FAILED:
	727	case CPU_DOWN_FAILED_FROZEN:
	728	start_cpu_timer(cpu);
	729	break;
ce421c79	730	case CPU_DEAD:
8bb78442	731	case CPU_DEAD_FROZEN:
ce421c79 AW	732	refresh_zone_stat_thresholds();
	733	break;
	734	default:
	735	break;
df9ecaba CL	736	}
	737	return NOTIFY_OK;
	738	}
	739
	740	static struct notifier_block __cpuinitdata vmstat_notifier =
	741	{ &vmstat_cpuup_callback, NULL, 0 };
	742
	743	int __init setup_vmstat(void)
	744	{
d1187ed2 CL	745	int cpu;
d1187ed2 CL	746
df9ecaba CL	747	refresh_zone_stat_thresholds();
df9ecaba CL	748	register_cpu_notifier(&vmstat_notifier);
d1187ed2 CL	749
	750	for_each_online_cpu(cpu)
	751	start_cpu_timer(cpu);
df9ecaba CL	752	return 0;
	753	}
	754	module_init(setup_vmstat)
	755	#endif