linux/mm/vmstat.c
Christoph Lameter 39bf6270f5 VM statistics: Make timer deferrable
VM statistics updates do not matter if the kernel is in idle powersaving
mode.  So allow the timer to be deferred.

It would be better though if we could switch the timer between deferrable
and nondeferrable based on differentials present.  The timer would start
out nondeferrable and if we find that there were no updates in the last
statistics interval then we would switch the timer to deferrable.  If the
timer later finds again that there are differentials then go to
nondeferrable again.

And yet another way would be to run the timer shortly before going to idle?

The solution here means that the VM counters may be slightly off during
idle since differentials may be still pending while the timer is deferred.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-11 08:29:32 -07:00

754 lines
17 KiB
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 <christoph@lameter.com>
*/
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/cpu.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)
static const char * const vmstat_text[] = {
/* Zoned VM counters */
"nr_free_pages",
"nr_active",
"nr_inactive",
"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