/*
   *  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 <christoph@lameter.com>

   */

  #include <linux/mm.h>

  #include <linux/module.h>

  #include <linux/cpu.h>

  void __get_zone_counts(unsigned long *active, unsigned long *inactive,
  			unsigned long *free, struct pglist_data *pgdat)
  {
  	struct zone *zones = pgdat->node_zones;
  	int i;
  
  	*active = 0;
  	*inactive = 0;
  	*free = 0;
  	for (i = 0; i < MAX_NR_ZONES; i++) {
  		*active += zones[i].nr_active;
  		*inactive += zones[i].nr_inactive;
  		*free += zones[i].free_pages;
  	}
  }
  
  void get_zone_counts(unsigned long *active,
  		unsigned long *inactive, unsigned long *free)
  {
  	struct pglist_data *pgdat;
  
  	*active = 0;
  	*inactive = 0;
  	*free = 0;
  	for_each_online_pgdat(pgdat) {
  		unsigned long l, m, n;
  		__get_zone_counts(&l, &m, &n, pgdat);
  		*active += l;
  		*inactive += m;
  		*free += n;
  	}
  }

  #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.
   */

  static 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_page_state(struct page *page, enum zone_stat_item item)
  {
  	struct zone *zone = page_zone(page);

  	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;

  	}
  }
  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.
   */
  void refresh_cpu_vm_stats(int cpu)
  {
  	struct zone *zone;
  	int i;
  	unsigned long flags;
  
  	for_each_zone(zone) {
  		struct per_cpu_pageset *pcp;

  		if (!populated_zone(zone))
  			continue;

  		pcp = zone_pcp(zone, cpu);
  
  		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
  			if (pcp->vm_stat_diff[i]) {
  				local_irq_save(flags);
  				zone_page_state_add(pcp->vm_stat_diff[i],
  					zone, i);
  				pcp->vm_stat_diff[i] = 0;
  				local_irq_restore(flags);
  			}
  	}
  }
  
  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, '
  ');
  	}
  	return 0;
  }
  
  struct seq_operations fragmentation_op = {
  	.start	= frag_start,
  	.next	= frag_next,
  	.stop	= frag_stop,
  	.show	= frag_show,
  };

  #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) xx "_dma", TEXT_FOR_DMA32(xx) xx "_normal", \
  					TEXT_FOR_HIGHMEM(xx)

  static char *vmstat_text[] = {

  	/* Zoned VM counters */

  	"nr_anon_pages",

  	"nr_mapped",

  	"nr_file_pages",

  	"nr_slab_reclaimable",
  	"nr_slab_unreclaimable",

  	"nr_page_table_pages",

  	"nr_dirty",

  	"nr_writeback",

  	"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,
  			   "
    pages free     %lu"
  			   "
          min      %lu"
  			   "
          low      %lu"
  			   "
          high     %lu"
  			   "
          active   %lu"
  			   "
          inactive %lu"
  			   "
          scanned  %lu (a: %lu i: %lu)"
  			   "
          spanned  %lu"
  			   "
          present  %lu",
  			   zone->free_pages,
  			   zone->pages_min,
  			   zone->pages_low,
  			   zone->pages_high,
  			   zone->nr_active,
  			   zone->nr_inactive,
  			   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, "
      %-12s %lu", vmstat_text[i],
  					zone_page_state(zone, i));

  		seq_printf(m,
  			   "
          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,
  			   ")"
  			   "
    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++) {
  				if (pageset->pcp[j].count)
  					break;
  			}
  			if (j == ARRAY_SIZE(pageset->pcp))
  				continue;
  			for (j = 0; j < ARRAY_SIZE(pageset->pcp); j++) {
  				seq_printf(m,
  					   "
      cpu: %i pcp: %i"
  					   "
                count: %i"
  					   "
                high:  %i"
  					   "
                batch: %i",
  					   i, j,
  					   pageset->pcp[j].count,
  					   pageset->pcp[j].high,
  					   pageset->pcp[j].batch);
  			}

  #ifdef CONFIG_SMP
  			seq_printf(m, "
    vm stats threshold: %d",
  					pageset->stat_threshold);
  #endif

  		}
  		seq_printf(m,
  			   "
    all_unreclaimable: %u"
  			   "
    prev_priority:     %i"
  			   "
    temp_priority:     %i"
  			   "
    start_pfn:         %lu",
  			   zone->all_unreclaimable,
  			   zone->prev_priority,
  			   zone->temp_priority,
  			   zone->zone_start_pfn);
  		spin_unlock_irqrestore(&zone->lock, flags);
  		seq_putc(m, '
  ');
  	}
  	return 0;
  }
  
  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
  ", vmstat_text[off], *l);
  	return 0;
  }
  
  static void vmstat_stop(struct seq_file *m, void *arg)
  {
  	kfree(m->private);
  	m->private = NULL;
  }
  
  struct seq_operations vmstat_op = {
  	.start	= vmstat_start,
  	.next	= vmstat_next,
  	.stop	= vmstat_stop,
  	.show	= vmstat_show,
  };
  
  #endif /* CONFIG_PROC_FS */

  #ifdef CONFIG_SMP
  /*
   * 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)
  {
  	switch (action) {
  		case CPU_UP_PREPARE:
  		case CPU_UP_CANCELED:
  		case CPU_DEAD:
  			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)
  {
  	refresh_zone_stat_thresholds();
  	register_cpu_notifier(&vmstat_notifier);
  	return 0;
  }
  module_init(setup_vmstat)
  #endif