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Date: Wed, 12 May 2021 12:11:33 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Mel Gorman <mgorman@...hsingularity.net>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: Chuck Lever <chuck.lever@...cle.com>,
Jesper Dangaard Brouer <brouer@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Michal Hocko <mhocko@...nel.org>,
Linux-MM <linux-mm@...ck.org>,
Linux-RT-Users <linux-rt-users@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/9] mm/vmstat: Convert NUMA statistics to basic NUMA
counters
On 5/12/21 11:54 AM, Mel Gorman wrote:
> NUMA statistics are maintained on the zone level for hits, misses, foreign
> etc but nothing relies on them being perfectly accurate for functional
> correctness. The counters are used by userspace to get a general overview
> of a workloads NUMA behaviour but the page allocator incurs a high cost to
> maintain perfect accuracy similar to what is required for a vmstat like
> NR_FREE_PAGES. There even is a sysctl vm.numa_stat to allow userspace to
> turn off the collection of NUMA statistics like NUMA_HIT.
>
> This patch converts NUMA_HIT and friends to be NUMA events with similar
> accuracy to VM events. There is a possibility that slight errors will be
> introduced but the overall trend as seen by userspace will be similar.
> The counters are no longer updated from vmstat_refresh context as it is
> unnecessary overhead for counters that may never be read by userspace.
> Note that counters could be maintained at the node level to save space
> but it would have a user-visible impact due to /proc/zoneinfo.
>
> [lkp@...el.com: Fix misplaced closing brace for !CONFIG_NUMA]
> Signed-off-by: Mel Gorman <mgorman@...hsingularity.net>
Acked-by: Vlastimil Babka <vbabka@...e.cz>
> ---
> drivers/base/node.c | 18 +++--
> include/linux/mmzone.h | 13 ++-
> include/linux/vmstat.h | 43 +++++-----
> mm/mempolicy.c | 2 +-
> mm/page_alloc.c | 12 +--
> mm/vmstat.c | 175 ++++++++++++++++-------------------------
> 6 files changed, 115 insertions(+), 148 deletions(-)
>
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index 2c36f61d30bc..9db297431b97 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -482,6 +482,7 @@ static DEVICE_ATTR(meminfo, 0444, node_read_meminfo, NULL);
> static ssize_t node_read_numastat(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> + fold_vm_numa_events();
> return sysfs_emit(buf,
> "numa_hit %lu\n"
> "numa_miss %lu\n"
> @@ -489,12 +490,12 @@ static ssize_t node_read_numastat(struct device *dev,
> "interleave_hit %lu\n"
> "local_node %lu\n"
> "other_node %lu\n",
> - sum_zone_numa_state(dev->id, NUMA_HIT),
> - sum_zone_numa_state(dev->id, NUMA_MISS),
> - sum_zone_numa_state(dev->id, NUMA_FOREIGN),
> - sum_zone_numa_state(dev->id, NUMA_INTERLEAVE_HIT),
> - sum_zone_numa_state(dev->id, NUMA_LOCAL),
> - sum_zone_numa_state(dev->id, NUMA_OTHER));
> + sum_zone_numa_event_state(dev->id, NUMA_HIT),
> + sum_zone_numa_event_state(dev->id, NUMA_MISS),
> + sum_zone_numa_event_state(dev->id, NUMA_FOREIGN),
> + sum_zone_numa_event_state(dev->id, NUMA_INTERLEAVE_HIT),
> + sum_zone_numa_event_state(dev->id, NUMA_LOCAL),
> + sum_zone_numa_event_state(dev->id, NUMA_OTHER));
> }
> static DEVICE_ATTR(numastat, 0444, node_read_numastat, NULL);
>
> @@ -512,10 +513,11 @@ static ssize_t node_read_vmstat(struct device *dev,
> sum_zone_node_page_state(nid, i));
>
> #ifdef CONFIG_NUMA
> - for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
> + fold_vm_numa_events();
> + for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++)
> len += sysfs_emit_at(buf, len, "%s %lu\n",
> numa_stat_name(i),
> - sum_zone_numa_state(nid, i));
> + sum_zone_numa_event_state(nid, i));
>
> #endif
> for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 30a1b5edbe90..d7740c97b87e 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -135,10 +135,10 @@ enum numa_stat_item {
> NUMA_INTERLEAVE_HIT, /* interleaver preferred this zone */
> NUMA_LOCAL, /* allocation from local node */
> NUMA_OTHER, /* allocation from other node */
> - NR_VM_NUMA_STAT_ITEMS
> + NR_VM_NUMA_EVENT_ITEMS
> };
> #else
> -#define NR_VM_NUMA_STAT_ITEMS 0
> +#define NR_VM_NUMA_EVENT_ITEMS 0
> #endif
>
> enum zone_stat_item {
> @@ -357,7 +357,12 @@ struct per_cpu_zonestat {
> s8 stat_threshold;
> #endif
> #ifdef CONFIG_NUMA
> - u16 vm_numa_stat_diff[NR_VM_NUMA_STAT_ITEMS];
> + /*
> + * Low priority inaccurate counters that are only folded
> + * on demand. Use a large type to avoid the overhead of
> + * folding during refresh_cpu_vm_stats.
> + */
> + unsigned long vm_numa_event[NR_VM_NUMA_EVENT_ITEMS];
> #endif
> };
>
> @@ -623,7 +628,7 @@ struct zone {
> ZONE_PADDING(_pad3_)
> /* Zone statistics */
> atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
> - atomic_long_t vm_numa_stat[NR_VM_NUMA_STAT_ITEMS];
> + atomic_long_t vm_numa_event[NR_VM_NUMA_EVENT_ITEMS];
> } ____cacheline_internodealigned_in_smp;
>
> enum pgdat_flags {
> diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
> index 0c5f36504613..59748bbbba4c 100644
> --- a/include/linux/vmstat.h
> +++ b/include/linux/vmstat.h
> @@ -138,34 +138,27 @@ static inline void vm_events_fold_cpu(int cpu)
> * Zone and node-based page accounting with per cpu differentials.
> */
> extern atomic_long_t vm_zone_stat[NR_VM_ZONE_STAT_ITEMS];
> -extern atomic_long_t vm_numa_stat[NR_VM_NUMA_STAT_ITEMS];
> extern atomic_long_t vm_node_stat[NR_VM_NODE_STAT_ITEMS];
> +extern atomic_long_t vm_numa_event[NR_VM_NUMA_EVENT_ITEMS];
>
> #ifdef CONFIG_NUMA
> -static inline void zone_numa_state_add(long x, struct zone *zone,
> - enum numa_stat_item item)
> +static inline void zone_numa_event_add(long x, struct zone *zone,
> + enum numa_stat_item item)
> {
> - atomic_long_add(x, &zone->vm_numa_stat[item]);
> - atomic_long_add(x, &vm_numa_stat[item]);
> + atomic_long_add(x, &zone->vm_numa_event[item]);
> + atomic_long_add(x, &vm_numa_event[item]);
> }
>
> -static inline unsigned long global_numa_state(enum numa_stat_item item)
> +static inline unsigned long zone_numa_event_state(struct zone *zone,
> + enum numa_stat_item item)
> {
> - long x = atomic_long_read(&vm_numa_stat[item]);
> -
> - return x;
> + return atomic_long_read(&zone->vm_numa_event[item]);
> }
>
> -static inline unsigned long zone_numa_state_snapshot(struct zone *zone,
> - enum numa_stat_item item)
> +static inline unsigned long
> +global_numa_event_state(enum numa_stat_item item)
> {
> - long x = atomic_long_read(&zone->vm_numa_stat[item]);
> - int cpu;
> -
> - for_each_online_cpu(cpu)
> - x += per_cpu_ptr(zone->per_cpu_zonestats, cpu)->vm_numa_stat_diff[item];
> -
> - return x;
> + return atomic_long_read(&vm_numa_event[item]);
> }
> #endif /* CONFIG_NUMA */
>
> @@ -245,18 +238,22 @@ static inline unsigned long zone_page_state_snapshot(struct zone *zone,
> }
>
> #ifdef CONFIG_NUMA
> -extern void __inc_numa_state(struct zone *zone, enum numa_stat_item item);
> +extern void __count_numa_event(struct zone *zone, enum numa_stat_item item);
> extern unsigned long sum_zone_node_page_state(int node,
> enum zone_stat_item item);
> -extern unsigned long sum_zone_numa_state(int node, enum numa_stat_item item);
> +extern unsigned long sum_zone_numa_event_state(int node, enum numa_stat_item item);
> extern unsigned long node_page_state(struct pglist_data *pgdat,
> enum node_stat_item item);
> extern unsigned long node_page_state_pages(struct pglist_data *pgdat,
> enum node_stat_item item);
> +extern void fold_vm_numa_events(void);
> #else
> #define sum_zone_node_page_state(node, item) global_zone_page_state(item)
> #define node_page_state(node, item) global_node_page_state(item)
> #define node_page_state_pages(node, item) global_node_page_state_pages(item)
> +static inline void fold_vm_numa_events(void)
> +{
> +}
> #endif /* CONFIG_NUMA */
>
> #ifdef CONFIG_SMP
> @@ -428,7 +425,7 @@ static inline const char *numa_stat_name(enum numa_stat_item item)
> static inline const char *node_stat_name(enum node_stat_item item)
> {
> return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
> - NR_VM_NUMA_STAT_ITEMS +
> + NR_VM_NUMA_EVENT_ITEMS +
> item];
> }
>
> @@ -440,7 +437,7 @@ static inline const char *lru_list_name(enum lru_list lru)
> static inline const char *writeback_stat_name(enum writeback_stat_item item)
> {
> return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
> - NR_VM_NUMA_STAT_ITEMS +
> + NR_VM_NUMA_EVENT_ITEMS +
> NR_VM_NODE_STAT_ITEMS +
> item];
> }
> @@ -449,7 +446,7 @@ static inline const char *writeback_stat_name(enum writeback_stat_item item)
> static inline const char *vm_event_name(enum vm_event_item item)
> {
> return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
> - NR_VM_NUMA_STAT_ITEMS +
> + NR_VM_NUMA_EVENT_ITEMS +
> NR_VM_NODE_STAT_ITEMS +
> NR_VM_WRITEBACK_STAT_ITEMS +
> item];
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index d79fa299b70c..9e4b406c79f8 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -2150,7 +2150,7 @@ static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
> return page;
> if (page && page_to_nid(page) == nid) {
> preempt_disable();
> - __inc_numa_state(page_zone(page), NUMA_INTERLEAVE_HIT);
> + __count_numa_event(page_zone(page), NUMA_INTERLEAVE_HIT);
> preempt_enable();
> }
> return page;
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index beca5ab7ddf3..eb1df4e3c956 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3469,12 +3469,12 @@ static inline void zone_statistics(struct zone *preferred_zone, struct zone *z)
> local_stat = NUMA_OTHER;
>
> if (zone_to_nid(z) == zone_to_nid(preferred_zone))
> - __inc_numa_state(z, NUMA_HIT);
> + __count_numa_event(z, NUMA_HIT);
> else {
> - __inc_numa_state(z, NUMA_MISS);
> - __inc_numa_state(preferred_zone, NUMA_FOREIGN);
> + __count_numa_event(z, NUMA_MISS);
> + __count_numa_event(preferred_zone, NUMA_FOREIGN);
> }
> - __inc_numa_state(z, local_stat);
> + __count_numa_event(z, local_stat);
> #endif
> }
>
> @@ -6746,8 +6746,8 @@ void __init setup_per_cpu_pageset(void)
> */
> for_each_possible_cpu(cpu) {
> struct per_cpu_zonestat *pzstats = &per_cpu(boot_zonestats, cpu);
> - memset(pzstats->vm_numa_stat_diff, 0,
> - sizeof(pzstats->vm_numa_stat_diff));
> + memset(pzstats->vm_numa_event, 0,
> + sizeof(pzstats->vm_numa_event));
> }
> #endif
>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index e3bcd317ea55..c6434bab7feb 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -31,8 +31,6 @@
>
> #include "internal.h"
>
> -#define NUMA_STATS_THRESHOLD (U16_MAX - 2)
> -
> #ifdef CONFIG_NUMA
> int sysctl_vm_numa_stat = ENABLE_NUMA_STAT;
>
> @@ -41,11 +39,12 @@ static void zero_zone_numa_counters(struct zone *zone)
> {
> int item, cpu;
>
> - for (item = 0; item < NR_VM_NUMA_STAT_ITEMS; item++) {
> - atomic_long_set(&zone->vm_numa_stat[item], 0);
> - for_each_online_cpu(cpu)
> - per_cpu_ptr(zone->per_cpu_zonestats, cpu)->vm_numa_stat_diff[item]
> + for (item = 0; item < NR_VM_NUMA_EVENT_ITEMS; item++) {
> + atomic_long_set(&zone->vm_numa_event[item], 0);
> + for_each_online_cpu(cpu) {
> + per_cpu_ptr(zone->per_cpu_zonestats, cpu)->vm_numa_event[item]
> = 0;
> + }
> }
> }
>
> @@ -63,8 +62,8 @@ static void zero_global_numa_counters(void)
> {
> int item;
>
> - for (item = 0; item < NR_VM_NUMA_STAT_ITEMS; item++)
> - atomic_long_set(&vm_numa_stat[item], 0);
> + for (item = 0; item < NR_VM_NUMA_EVENT_ITEMS; item++)
> + atomic_long_set(&vm_numa_event[item], 0);
> }
>
> static void invalid_numa_statistics(void)
> @@ -161,10 +160,9 @@ void vm_events_fold_cpu(int cpu)
> * vm_stat contains the global counters
> */
> atomic_long_t vm_zone_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_smp;
> -atomic_long_t vm_numa_stat[NR_VM_NUMA_STAT_ITEMS] __cacheline_aligned_in_smp;
> atomic_long_t vm_node_stat[NR_VM_NODE_STAT_ITEMS] __cacheline_aligned_in_smp;
> +atomic_long_t vm_numa_event[NR_VM_NUMA_EVENT_ITEMS] __cacheline_aligned_in_smp;
> EXPORT_SYMBOL(vm_zone_stat);
> -EXPORT_SYMBOL(vm_numa_stat);
> EXPORT_SYMBOL(vm_node_stat);
>
> #ifdef CONFIG_SMP
> @@ -706,8 +704,7 @@ EXPORT_SYMBOL(dec_node_page_state);
> * Fold a differential into the global counters.
> * Returns the number of counters updated.
> */
> -#ifdef CONFIG_NUMA
> -static int fold_diff(int *zone_diff, int *numa_diff, int *node_diff)
> +static int fold_diff(int *zone_diff, int *node_diff)
> {
> int i;
> int changes = 0;
> @@ -718,12 +715,6 @@ static int fold_diff(int *zone_diff, int *numa_diff, int *node_diff)
> changes++;
> }
>
> - for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
> - if (numa_diff[i]) {
> - atomic_long_add(numa_diff[i], &vm_numa_stat[i]);
> - changes++;
> - }
> -
> for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
> if (node_diff[i]) {
> atomic_long_add(node_diff[i], &vm_node_stat[i]);
> @@ -731,26 +722,34 @@ static int fold_diff(int *zone_diff, int *numa_diff, int *node_diff)
> }
> return changes;
> }
> -#else
> -static int fold_diff(int *zone_diff, int *node_diff)
> +
> +#ifdef CONFIG_NUMA
> +static void fold_vm_zone_numa_events(struct zone *zone)
> {
> - int i;
> - int changes = 0;
> + unsigned long zone_numa_events[NR_VM_NUMA_EVENT_ITEMS] = { 0, };
> + int cpu;
> + enum numa_stat_item item;
>
> - for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
> - if (zone_diff[i]) {
> - atomic_long_add(zone_diff[i], &vm_zone_stat[i]);
> - changes++;
> - }
> + for_each_online_cpu(cpu) {
> + struct per_cpu_zonestat *pzstats;
>
> - for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
> - if (node_diff[i]) {
> - atomic_long_add(node_diff[i], &vm_node_stat[i]);
> - changes++;
> + pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
> + for (item = 0; item < NR_VM_NUMA_EVENT_ITEMS; item++)
> + zone_numa_events[item] += xchg(&pzstats->vm_numa_event[item], 0);
> }
> - return changes;
> +
> + for (item = 0; item < NR_VM_NUMA_EVENT_ITEMS; item++)
> + zone_numa_event_add(zone_numa_events[item], zone, item);
> }
> -#endif /* CONFIG_NUMA */
> +
> +void fold_vm_numa_events(void)
> +{
> + struct zone *zone;
> +
> + for_each_populated_zone(zone)
> + fold_vm_zone_numa_events(zone);
> +}
> +#endif
>
> /*
> * Update the zone counters for the current cpu.
> @@ -774,15 +773,14 @@ static int refresh_cpu_vm_stats(bool do_pagesets)
> struct zone *zone;
> int i;
> int global_zone_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
> -#ifdef CONFIG_NUMA
> - int global_numa_diff[NR_VM_NUMA_STAT_ITEMS] = { 0, };
> -#endif
> int global_node_diff[NR_VM_NODE_STAT_ITEMS] = { 0, };
> int changes = 0;
>
> for_each_populated_zone(zone) {
> struct per_cpu_zonestat __percpu *pzstats = zone->per_cpu_zonestats;
> +#ifdef CONFIG_NUMA
> struct per_cpu_pages __percpu *pcp = zone->per_cpu_pageset;
> +#endif
>
> for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
> int v;
> @@ -799,17 +797,6 @@ static int refresh_cpu_vm_stats(bool do_pagesets)
> }
> }
> #ifdef CONFIG_NUMA
> - for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++) {
> - int v;
> -
> - v = this_cpu_xchg(pzstats->vm_numa_stat_diff[i], 0);
> - if (v) {
> -
> - atomic_long_add(v, &zone->vm_numa_stat[i]);
> - global_numa_diff[i] += v;
> - __this_cpu_write(pcp->expire, 3);
> - }
> - }
>
> if (do_pagesets) {
> cond_resched();
> @@ -857,12 +844,7 @@ static int refresh_cpu_vm_stats(bool do_pagesets)
> }
> }
>
> -#ifdef CONFIG_NUMA
> - changes += fold_diff(global_zone_diff, global_numa_diff,
> - global_node_diff);
> -#else
> changes += fold_diff(global_zone_diff, global_node_diff);
> -#endif
> return changes;
> }
>
> @@ -877,9 +859,6 @@ void cpu_vm_stats_fold(int cpu)
> struct zone *zone;
> int i;
> int global_zone_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
> -#ifdef CONFIG_NUMA
> - int global_numa_diff[NR_VM_NUMA_STAT_ITEMS] = { 0, };
> -#endif
> int global_node_diff[NR_VM_NODE_STAT_ITEMS] = { 0, };
>
> for_each_populated_zone(zone) {
> @@ -887,7 +866,7 @@ void cpu_vm_stats_fold(int cpu)
>
> pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
>
> - for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
> + for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
> if (pzstats->vm_stat_diff[i]) {
> int v;
>
> @@ -896,17 +875,17 @@ void cpu_vm_stats_fold(int cpu)
> atomic_long_add(v, &zone->vm_stat[i]);
> global_zone_diff[i] += v;
> }
> -
> + }
> #ifdef CONFIG_NUMA
> - for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
> - if (pzstats->vm_numa_stat_diff[i]) {
> - int v;
> + for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++) {
> + if (pzstats->vm_numa_event[i]) {
> + unsigned long v;
>
> - v = pzstats->vm_numa_stat_diff[i];
> - pzstats->vm_numa_stat_diff[i] = 0;
> - atomic_long_add(v, &zone->vm_numa_stat[i]);
> - global_numa_diff[i] += v;
> + v = pzstats->vm_numa_event[i];
> + pzstats->vm_numa_event[i] = 0;
> + zone_numa_event_add(v, zone, i);
> }
> + }
> #endif
> }
>
> @@ -926,11 +905,7 @@ void cpu_vm_stats_fold(int cpu)
> }
> }
>
> -#ifdef CONFIG_NUMA
> - fold_diff(global_zone_diff, global_numa_diff, global_node_diff);
> -#else
> fold_diff(global_zone_diff, global_node_diff);
> -#endif
> }
>
> /*
> @@ -939,43 +914,37 @@ void cpu_vm_stats_fold(int cpu)
> */
> void drain_zonestat(struct zone *zone, struct per_cpu_zonestat *pzstats)
> {
> + unsigned long v;
> int i;
>
> - for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
> + for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
> if (pzstats->vm_stat_diff[i]) {
> - int v = pzstats->vm_stat_diff[i];
> + v = pzstats->vm_stat_diff[i];
> pzstats->vm_stat_diff[i] = 0;
> - atomic_long_add(v, &zone->vm_stat[i]);
> - atomic_long_add(v, &vm_zone_stat[i]);
> + zone_page_state_add(v, zone, i);
> }
> + }
>
> #ifdef CONFIG_NUMA
> - for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
> - if (pzstats->vm_numa_stat_diff[i]) {
> - int v = pzstats->vm_numa_stat_diff[i];
> -
> - pzstats->vm_numa_stat_diff[i] = 0;
> - atomic_long_add(v, &zone->vm_numa_stat[i]);
> - atomic_long_add(v, &vm_numa_stat[i]);
> + for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++) {
> + if (pzstats->vm_numa_event[i]) {
> + v = pzstats->vm_numa_event[i];
> + pzstats->vm_numa_event[i] = 0;
> + zone_numa_event_add(v, zone, i);
> }
> + }
> #endif
> }
> #endif
>
> #ifdef CONFIG_NUMA
> -void __inc_numa_state(struct zone *zone,
> +/* See __count_vm_event comment on why raw_cpu_inc is used. */
> +void __count_numa_event(struct zone *zone,
> enum numa_stat_item item)
> {
> struct per_cpu_zonestat __percpu *pzstats = zone->per_cpu_zonestats;
> - u16 __percpu *p = pzstats->vm_numa_stat_diff + item;
> - u16 v;
> -
> - v = __this_cpu_inc_return(*p);
>
> - if (unlikely(v > NUMA_STATS_THRESHOLD)) {
> - zone_numa_state_add(v, zone, item);
> - __this_cpu_write(*p, 0);
> - }
> + raw_cpu_inc(pzstats->vm_numa_event[item]);
> }
>
> /*
> @@ -996,19 +965,16 @@ unsigned long sum_zone_node_page_state(int node,
> return count;
> }
>
> -/*
> - * Determine the per node value of a numa stat item. To avoid deviation,
> - * the per cpu stat number in vm_numa_stat_diff[] is also included.
> - */
> -unsigned long sum_zone_numa_state(int node,
> +/* Determine the per node value of a numa stat item. */
> +unsigned long sum_zone_numa_event_state(int node,
> enum numa_stat_item item)
> {
> struct zone *zones = NODE_DATA(node)->node_zones;
> - int i;
> unsigned long count = 0;
> + int i;
>
> for (i = 0; i < MAX_NR_ZONES; i++)
> - count += zone_numa_state_snapshot(zones + i, item);
> + count += zone_numa_event_state(zones + i, item);
>
> return count;
> }
> @@ -1687,9 +1653,9 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
> zone_page_state(zone, i));
>
> #ifdef CONFIG_NUMA
> - for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
> + for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++)
> seq_printf(m, "\n %-12s %lu", numa_stat_name(i),
> - zone_numa_state_snapshot(zone, i));
> + zone_numa_event_state(zone, i));
> #endif
>
> seq_printf(m, "\n pagesets");
> @@ -1743,7 +1709,7 @@ static const struct seq_operations zoneinfo_op = {
> };
>
> #define NR_VMSTAT_ITEMS (NR_VM_ZONE_STAT_ITEMS + \
> - NR_VM_NUMA_STAT_ITEMS + \
> + NR_VM_NUMA_EVENT_ITEMS + \
> NR_VM_NODE_STAT_ITEMS + \
> NR_VM_WRITEBACK_STAT_ITEMS + \
> (IS_ENABLED(CONFIG_VM_EVENT_COUNTERS) ? \
> @@ -1758,6 +1724,7 @@ static void *vmstat_start(struct seq_file *m, loff_t *pos)
> return NULL;
>
> BUILD_BUG_ON(ARRAY_SIZE(vmstat_text) < NR_VMSTAT_ITEMS);
> + fold_vm_numa_events();
> v = kmalloc_array(NR_VMSTAT_ITEMS, sizeof(unsigned long), GFP_KERNEL);
> m->private = v;
> if (!v)
> @@ -1767,9 +1734,9 @@ static void *vmstat_start(struct seq_file *m, loff_t *pos)
> v += NR_VM_ZONE_STAT_ITEMS;
>
> #ifdef CONFIG_NUMA
> - for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
> - v[i] = global_numa_state(i);
> - v += NR_VM_NUMA_STAT_ITEMS;
> + for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++)
> + v[i] = global_numa_event_state(i);
> + v += NR_VM_NUMA_EVENT_ITEMS;
> #endif
>
> for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
> @@ -1939,11 +1906,7 @@ static bool need_update(int cpu)
> if (memchr_inv(pzstats->vm_stat_diff, 0, NR_VM_ZONE_STAT_ITEMS *
> sizeof(pzstats->vm_stat_diff[0])))
> return true;
> -#ifdef CONFIG_NUMA
> - if (memchr_inv(pzstats->vm_numa_stat_diff, 0, NR_VM_NUMA_STAT_ITEMS *
> - sizeof(pzstats->vm_numa_stat_diff[0])))
> - return true;
> -#endif
> +
> if (last_pgdat == zone->zone_pgdat)
> continue;
> last_pgdat = zone->zone_pgdat;
>
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