Increments and decrements are usually grouped rather than mixed. We can optimize the inc and dec functions for that case. Increment and decrement the counters by 50% more than the threshold in those cases and set the differential accordingly. This decreases the need to update the atomic counters. The idea came originally from Andrew Morton. The overstepping alone was sufficient to address the contention issue found when updating the global and the per zone counters from 160 processors. Also remove some code in dec_zone_page_state. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
606 lines
13 KiB
C
606 lines
13 KiB
C
/*
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* linux/mm/vmstat.c
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*
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* Manages VM statistics
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*
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* zoned VM statistics
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* Copyright (C) 2006 Silicon Graphics, Inc.,
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* Christoph Lameter <christoph@lameter.com>
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*/
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#include <linux/config.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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void __get_zone_counts(unsigned long *active, unsigned long *inactive,
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unsigned long *free, struct pglist_data *pgdat)
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{
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struct zone *zones = pgdat->node_zones;
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int i;
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*active = 0;
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*inactive = 0;
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*free = 0;
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for (i = 0; i < MAX_NR_ZONES; i++) {
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*active += zones[i].nr_active;
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*inactive += zones[i].nr_inactive;
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*free += zones[i].free_pages;
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}
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}
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void get_zone_counts(unsigned long *active,
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unsigned long *inactive, unsigned long *free)
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{
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struct pglist_data *pgdat;
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*active = 0;
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*inactive = 0;
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*free = 0;
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for_each_online_pgdat(pgdat) {
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unsigned long l, m, n;
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__get_zone_counts(&l, &m, &n, pgdat);
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*active += l;
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*inactive += m;
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*free += n;
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}
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}
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#ifdef CONFIG_VM_EVENT_COUNTERS
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DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
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EXPORT_PER_CPU_SYMBOL(vm_event_states);
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static void sum_vm_events(unsigned long *ret, cpumask_t *cpumask)
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{
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int cpu = 0;
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int i;
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memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
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cpu = first_cpu(*cpumask);
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while (cpu < NR_CPUS) {
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struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
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cpu = next_cpu(cpu, *cpumask);
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if (cpu < NR_CPUS)
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prefetch(&per_cpu(vm_event_states, cpu));
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for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
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ret[i] += this->event[i];
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}
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}
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/*
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* Accumulate the vm event counters across all CPUs.
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* The result is unavoidably approximate - it can change
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* during and after execution of this function.
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*/
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void all_vm_events(unsigned long *ret)
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{
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sum_vm_events(ret, &cpu_online_map);
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}
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EXPORT_SYMBOL_GPL(all_vm_events);
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#ifdef CONFIG_HOTPLUG
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/*
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* Fold the foreign cpu events into our own.
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*
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* This is adding to the events on one processor
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* but keeps the global counts constant.
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*/
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void vm_events_fold_cpu(int cpu)
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{
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struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
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int i;
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for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
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count_vm_events(i, fold_state->event[i]);
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fold_state->event[i] = 0;
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}
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}
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#endif /* CONFIG_HOTPLUG */
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#endif /* CONFIG_VM_EVENT_COUNTERS */
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/*
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* Manage combined zone based / global counters
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*
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* vm_stat contains the global counters
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*/
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atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
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EXPORT_SYMBOL(vm_stat);
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#ifdef CONFIG_SMP
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#define STAT_THRESHOLD 32
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/*
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* Determine pointer to currently valid differential byte given a zone and
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* the item number.
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*
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* Preemption must be off
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*/
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static inline s8 *diff_pointer(struct zone *zone, enum zone_stat_item item)
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{
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return &zone_pcp(zone, smp_processor_id())->vm_stat_diff[item];
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}
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/*
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* For use when we know that interrupts are disabled.
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*/
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void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
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int delta)
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{
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s8 *p;
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long x;
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p = diff_pointer(zone, item);
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x = delta + *p;
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if (unlikely(x > STAT_THRESHOLD || x < -STAT_THRESHOLD)) {
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zone_page_state_add(x, zone, item);
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x = 0;
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}
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*p = x;
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}
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EXPORT_SYMBOL(__mod_zone_page_state);
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/*
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* For an unknown interrupt state
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*/
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void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
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int delta)
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{
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unsigned long flags;
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local_irq_save(flags);
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__mod_zone_page_state(zone, item, delta);
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local_irq_restore(flags);
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}
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EXPORT_SYMBOL(mod_zone_page_state);
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/*
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* Optimized increment and decrement functions.
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*
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* These are only for a single page and therefore can take a struct page *
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* argument instead of struct zone *. This allows the inclusion of the code
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* generated for page_zone(page) into the optimized functions.
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*
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* No overflow check is necessary and therefore the differential can be
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* incremented or decremented in place which may allow the compilers to
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* generate better code.
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*
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* The increment or decrement is known and therefore one boundary check can
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* be omitted.
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*
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* Some processors have inc/dec instructions that are atomic vs an interrupt.
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* However, the code must first determine the differential location in a zone
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* based on the processor number and then inc/dec the counter. There is no
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* guarantee without disabling preemption that the processor will not change
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* in between and therefore the atomicity vs. interrupt cannot be exploited
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* in a useful way here.
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*/
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static void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
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{
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s8 *p = diff_pointer(zone, item);
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(*p)++;
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if (unlikely(*p > STAT_THRESHOLD)) {
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zone_page_state_add(*p + STAT_THRESHOLD / 2, zone, item);
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*p = -STAT_THRESHOLD / 2;
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}
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}
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void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
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{
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__inc_zone_state(page_zone(page), item);
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}
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EXPORT_SYMBOL(__inc_zone_page_state);
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void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
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{
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struct zone *zone = page_zone(page);
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s8 *p = diff_pointer(zone, item);
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(*p)--;
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if (unlikely(*p < -STAT_THRESHOLD)) {
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zone_page_state_add(*p - STAT_THRESHOLD / 2, zone, item);
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*p = STAT_THRESHOLD /2;
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}
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}
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EXPORT_SYMBOL(__dec_zone_page_state);
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void inc_zone_state(struct zone *zone, enum zone_stat_item item)
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{
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unsigned long flags;
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local_irq_save(flags);
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__inc_zone_state(zone, item);
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local_irq_restore(flags);
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}
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void inc_zone_page_state(struct page *page, enum zone_stat_item item)
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{
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unsigned long flags;
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struct zone *zone;
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zone = page_zone(page);
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local_irq_save(flags);
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__inc_zone_state(zone, item);
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local_irq_restore(flags);
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}
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EXPORT_SYMBOL(inc_zone_page_state);
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void dec_zone_page_state(struct page *page, enum zone_stat_item item)
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{
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unsigned long flags;
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local_irq_save(flags);
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__dec_zone_page_state(page, item);
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local_irq_restore(flags);
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}
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EXPORT_SYMBOL(dec_zone_page_state);
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/*
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* Update the zone counters for one cpu.
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*/
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void refresh_cpu_vm_stats(int cpu)
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{
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struct zone *zone;
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int i;
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unsigned long flags;
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for_each_zone(zone) {
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struct per_cpu_pageset *pcp;
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pcp = zone_pcp(zone, cpu);
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for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
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if (pcp->vm_stat_diff[i]) {
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local_irq_save(flags);
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zone_page_state_add(pcp->vm_stat_diff[i],
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zone, i);
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pcp->vm_stat_diff[i] = 0;
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local_irq_restore(flags);
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}
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}
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}
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static void __refresh_cpu_vm_stats(void *dummy)
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{
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refresh_cpu_vm_stats(smp_processor_id());
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}
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/*
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* Consolidate all counters.
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*
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* Note that the result is less inaccurate but still inaccurate
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* if concurrent processes are allowed to run.
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*/
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void refresh_vm_stats(void)
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{
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on_each_cpu(__refresh_cpu_vm_stats, NULL, 0, 1);
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}
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EXPORT_SYMBOL(refresh_vm_stats);
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#endif
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#ifdef CONFIG_NUMA
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/*
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* zonelist = the list of zones passed to the allocator
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* z = the zone from which the allocation occurred.
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*
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* Must be called with interrupts disabled.
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*/
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void zone_statistics(struct zonelist *zonelist, struct zone *z)
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{
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if (z->zone_pgdat == zonelist->zones[0]->zone_pgdat) {
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__inc_zone_state(z, NUMA_HIT);
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} else {
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__inc_zone_state(z, NUMA_MISS);
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__inc_zone_state(zonelist->zones[0], NUMA_FOREIGN);
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}
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if (z->zone_pgdat == NODE_DATA(numa_node_id()))
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__inc_zone_state(z, NUMA_LOCAL);
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else
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__inc_zone_state(z, NUMA_OTHER);
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}
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#endif
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#ifdef CONFIG_PROC_FS
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#include <linux/seq_file.h>
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static void *frag_start(struct seq_file *m, loff_t *pos)
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{
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pg_data_t *pgdat;
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loff_t node = *pos;
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for (pgdat = first_online_pgdat();
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pgdat && node;
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pgdat = next_online_pgdat(pgdat))
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--node;
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return pgdat;
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}
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static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
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{
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pg_data_t *pgdat = (pg_data_t *)arg;
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(*pos)++;
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return next_online_pgdat(pgdat);
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}
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static void frag_stop(struct seq_file *m, void *arg)
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{
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}
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/*
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* This walks the free areas for each zone.
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*/
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static int frag_show(struct seq_file *m, void *arg)
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{
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pg_data_t *pgdat = (pg_data_t *)arg;
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struct zone *zone;
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struct zone *node_zones = pgdat->node_zones;
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unsigned long flags;
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int order;
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for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
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if (!populated_zone(zone))
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continue;
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spin_lock_irqsave(&zone->lock, flags);
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seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
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for (order = 0; order < MAX_ORDER; ++order)
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seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
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spin_unlock_irqrestore(&zone->lock, flags);
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seq_putc(m, '\n');
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}
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return 0;
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}
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struct seq_operations fragmentation_op = {
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.start = frag_start,
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.next = frag_next,
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.stop = frag_stop,
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.show = frag_show,
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};
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static char *vmstat_text[] = {
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/* Zoned VM counters */
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"nr_anon_pages",
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"nr_mapped",
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"nr_file_pages",
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"nr_slab",
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"nr_page_table_pages",
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"nr_dirty",
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"nr_writeback",
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"nr_unstable",
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"nr_bounce",
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#ifdef CONFIG_NUMA
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"numa_hit",
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"numa_miss",
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"numa_foreign",
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"numa_interleave",
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"numa_local",
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"numa_other",
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#endif
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#ifdef CONFIG_VM_EVENT_COUNTERS
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"pgpgin",
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"pgpgout",
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"pswpin",
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"pswpout",
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"pgalloc_dma",
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"pgalloc_dma32",
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"pgalloc_normal",
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"pgalloc_high",
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"pgfree",
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"pgactivate",
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"pgdeactivate",
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"pgfault",
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"pgmajfault",
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"pgrefill_dma",
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"pgrefill_dma32",
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"pgrefill_normal",
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"pgrefill_high",
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"pgsteal_dma",
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"pgsteal_dma32",
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"pgsteal_normal",
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"pgsteal_high",
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"pgscan_kswapd_dma",
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"pgscan_kswapd_dma32",
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"pgscan_kswapd_normal",
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"pgscan_kswapd_high",
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"pgscan_direct_dma",
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"pgscan_direct_dma32",
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"pgscan_direct_normal",
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"pgscan_direct_high",
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"pginodesteal",
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"slabs_scanned",
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"kswapd_steal",
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"kswapd_inodesteal",
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"pageoutrun",
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"allocstall",
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"pgrotated",
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#endif
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};
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/*
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* Output information about zones in @pgdat.
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*/
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static int zoneinfo_show(struct seq_file *m, void *arg)
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{
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pg_data_t *pgdat = arg;
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struct zone *zone;
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struct zone *node_zones = pgdat->node_zones;
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unsigned long flags;
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for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; zone++) {
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int i;
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if (!populated_zone(zone))
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continue;
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spin_lock_irqsave(&zone->lock, flags);
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seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
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seq_printf(m,
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"\n pages free %lu"
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"\n min %lu"
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"\n low %lu"
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"\n high %lu"
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"\n active %lu"
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"\n inactive %lu"
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"\n scanned %lu (a: %lu i: %lu)"
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"\n spanned %lu"
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"\n present %lu",
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zone->free_pages,
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zone->pages_min,
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zone->pages_low,
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zone->pages_high,
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zone->nr_active,
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zone->nr_inactive,
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zone->pages_scanned,
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zone->nr_scan_active, zone->nr_scan_inactive,
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zone->spanned_pages,
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zone->present_pages);
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for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
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seq_printf(m, "\n %-12s %lu", vmstat_text[i],
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zone_page_state(zone, i));
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seq_printf(m,
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"\n protection: (%lu",
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zone->lowmem_reserve[0]);
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for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
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seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
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seq_printf(m,
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")"
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"\n pagesets");
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for_each_online_cpu(i) {
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struct per_cpu_pageset *pageset;
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int j;
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pageset = zone_pcp(zone, i);
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for (j = 0; j < ARRAY_SIZE(pageset->pcp); j++) {
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if (pageset->pcp[j].count)
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break;
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}
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if (j == ARRAY_SIZE(pageset->pcp))
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continue;
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for (j = 0; j < ARRAY_SIZE(pageset->pcp); j++) {
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seq_printf(m,
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"\n cpu: %i pcp: %i"
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"\n count: %i"
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"\n high: %i"
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"\n batch: %i",
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i, j,
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pageset->pcp[j].count,
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pageset->pcp[j].high,
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pageset->pcp[j].batch);
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}
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}
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seq_printf(m,
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"\n all_unreclaimable: %u"
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"\n prev_priority: %i"
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"\n temp_priority: %i"
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"\n start_pfn: %lu",
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zone->all_unreclaimable,
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zone->prev_priority,
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zone->temp_priority,
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zone->zone_start_pfn);
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spin_unlock_irqrestore(&zone->lock, flags);
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seq_putc(m, '\n');
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}
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return 0;
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}
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struct seq_operations zoneinfo_op = {
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.start = frag_start, /* iterate over all zones. The same as in
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* fragmentation. */
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.next = frag_next,
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.stop = frag_stop,
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.show = zoneinfo_show,
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};
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static void *vmstat_start(struct seq_file *m, loff_t *pos)
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{
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unsigned long *v;
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#ifdef CONFIG_VM_EVENT_COUNTERS
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unsigned long *e;
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#endif
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int i;
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|
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if (*pos >= ARRAY_SIZE(vmstat_text))
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return NULL;
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|
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#ifdef CONFIG_VM_EVENT_COUNTERS
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v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long)
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+ sizeof(struct vm_event_state), GFP_KERNEL);
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#else
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v = kmalloc(NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long),
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GFP_KERNEL);
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#endif
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m->private = v;
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if (!v)
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return ERR_PTR(-ENOMEM);
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|
for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
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|
v[i] = global_page_state(i);
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|
#ifdef CONFIG_VM_EVENT_COUNTERS
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|
e = v + NR_VM_ZONE_STAT_ITEMS;
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|
all_vm_events(e);
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e[PGPGIN] /= 2; /* sectors -> kbytes */
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|
e[PGPGOUT] /= 2;
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|
#endif
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|
return v + *pos;
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}
|
|
|
|
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);
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|
return 0;
|
|
}
|
|
|
|
static void vmstat_stop(struct seq_file *m, void *arg)
|
|
{
|
|
kfree(m->private);
|
|
m->private = NULL;
|
|
}
|
|
|
|
struct seq_operations vmstat_op = {
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|
.start = vmstat_start,
|
|
.next = vmstat_next,
|
|
.stop = vmstat_stop,
|
|
.show = vmstat_show,
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|
};
|
|
|
|
#endif /* CONFIG_PROC_FS */
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|
|