linux-xiaomi-chiron/include/linux/vmstat.h
Mel Gorman 28f836b677 mm/page_alloc: split per cpu page lists and zone stats
The PCP (per-cpu page allocator in page_alloc.c) shares locking
requirements with vmstat and the zone lock which is inconvenient and
causes some issues.  For example, the PCP list and vmstat share the same
per-cpu space meaning that it's possible that vmstat updates dirty cache
lines holding per-cpu lists across CPUs unless padding is used.  Second,
PREEMPT_RT does not want to disable IRQs for too long in the page
allocator.

This series splits the locking requirements and uses locks types more
suitable for PREEMPT_RT, reduces the time when special locking is required
for stats and reduces the time when IRQs need to be disabled on
!PREEMPT_RT kernels.

Why local_lock?  PREEMPT_RT considers the following sequence to be unsafe
as documented in Documentation/locking/locktypes.rst

   local_irq_disable();
   spin_lock(&lock);

The pcp allocator has this sequence for rmqueue_pcplist (local_irq_save)
-> __rmqueue_pcplist -> rmqueue_bulk (spin_lock).  While it's possible to
separate this out, it generally means there are points where we enable
IRQs and reenable them again immediately.  To prevent a migration and the
per-cpu pointer going stale, migrate_disable is also needed.  That is a
custom lock that is similar, but worse, than local_lock.  Furthermore, on
PREEMPT_RT, it's undesirable to leave IRQs disabled for too long.  By
converting to local_lock which disables migration on PREEMPT_RT, the
locking requirements can be separated and start moving the protections for
PCP, stats and the zone lock to PREEMPT_RT-safe equivalent locking.  As a
bonus, local_lock also means that PROVE_LOCKING does something useful.

After that, it's obvious that zone_statistics incurs too much overhead and
leaves IRQs disabled for longer than necessary on !PREEMPT_RT kernels.
zone_statistics uses perfectly accurate counters requiring IRQs be
disabled for parallel RMW sequences when inaccurate ones like vm_events
would do.  The series makes the NUMA statistics (NUMA_HIT and friends)
inaccurate counters that then require no special protection on
!PREEMPT_RT.

The bulk page allocator can then do stat updates in bulk with IRQs enabled
which should improve the efficiency.  Technically, this could have been
done without the local_lock and vmstat conversion work and the order
simply reflects the timing of when different series were implemented.

Finally, there are places where we conflate IRQs being disabled for the
PCP with the IRQ-safe zone spinlock.  The remainder of the series reduces
the scope of what is protected by disabled IRQs on !PREEMPT_RT kernels.
By the end of the series, page_alloc.c does not call local_irq_save so the
locking scope is a bit clearer.  The one exception is that modifying
NR_FREE_PAGES still happens in places where it's known the IRQs are
disabled as it's harmless for PREEMPT_RT and would be expensive to split
the locking there.

No performance data is included because despite the overhead of the stats,
it's within the noise for most workloads on !PREEMPT_RT.  However, Jesper
Dangaard Brouer ran a page allocation microbenchmark on a E5-1650 v4 @
3.60GHz CPU on the first version of this series.  Focusing on the array
variant of the bulk page allocator reveals the following.

(CPU: Intel(R) Xeon(R) CPU E5-1650 v4 @ 3.60GHz)
ARRAY variant: time_bulk_page_alloc_free_array: step=bulk size

         Baseline        Patched
 1       56.383          54.225 (+3.83%)
 2       40.047          35.492 (+11.38%)
 3       37.339          32.643 (+12.58%)
 4       35.578          30.992 (+12.89%)
 8       33.592          29.606 (+11.87%)
 16      32.362          28.532 (+11.85%)
 32      31.476          27.728 (+11.91%)
 64      30.633          27.252 (+11.04%)
 128     30.596          27.090 (+11.46%)

While this is a positive outcome, the series is more likely to be
interesting to the RT people in terms of getting parts of the PREEMPT_RT
tree into mainline.

This patch (of 9):

The per-cpu page allocator lists and the per-cpu vmstat deltas are stored
in the same struct per_cpu_pages even though vmstats have no direct impact
on the per-cpu page lists.  This is inconsistent because the vmstats for a
node are stored on a dedicated structure.  The bigger issue is that the
per_cpu_pages structure is not cache-aligned and stat updates either cache
conflict with adjacent per-cpu lists incurring a runtime cost or padding
is required incurring a memory cost.

This patch splits the per-cpu pagelists and the vmstat deltas into
separate structures.  It's mostly a mechanical conversion but some
variable renaming is done to clearly distinguish the per-cpu pages
structure (pcp) from the vmstats (pzstats).

Superficially, this appears to increase the size of the per_cpu_pages
structure but the movement of expire fills a structure hole so there is no
impact overall.

[mgorman@techsingularity.net: make it W=1 cleaner]
  Link: https://lkml.kernel.org/r/20210514144622.GA3735@techsingularity.net
[mgorman@techsingularity.net: make it W=1 even cleaner]
  Link: https://lkml.kernel.org/r/20210516140705.GB3735@techsingularity.net
[lkp@intel.com: check struct per_cpu_zonestat has a non-zero size]
[vbabka@suse.cz: Init zone->per_cpu_zonestats properly]

Link: https://lkml.kernel.org/r/20210512095458.30632-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20210512095458.30632-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-29 10:53:54 -07:00

545 lines
14 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_VMSTAT_H
#define _LINUX_VMSTAT_H
#include <linux/types.h>
#include <linux/percpu.h>
#include <linux/mmzone.h>
#include <linux/vm_event_item.h>
#include <linux/atomic.h>
#include <linux/static_key.h>
#include <linux/mmdebug.h>
extern int sysctl_stat_interval;
#ifdef CONFIG_NUMA
#define ENABLE_NUMA_STAT 1
#define DISABLE_NUMA_STAT 0
extern int sysctl_vm_numa_stat;
DECLARE_STATIC_KEY_TRUE(vm_numa_stat_key);
int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos);
#endif
struct reclaim_stat {
unsigned nr_dirty;
unsigned nr_unqueued_dirty;
unsigned nr_congested;
unsigned nr_writeback;
unsigned nr_immediate;
unsigned nr_pageout;
unsigned nr_activate[ANON_AND_FILE];
unsigned nr_ref_keep;
unsigned nr_unmap_fail;
unsigned nr_lazyfree_fail;
};
enum writeback_stat_item {
NR_DIRTY_THRESHOLD,
NR_DIRTY_BG_THRESHOLD,
NR_VM_WRITEBACK_STAT_ITEMS,
};
#ifdef CONFIG_VM_EVENT_COUNTERS
/*
* Light weight per cpu counter implementation.
*
* Counters should only be incremented and no critical kernel component
* should rely on the counter values.
*
* Counters are handled completely inline. On many platforms the code
* generated will simply be the increment of a global address.
*/
struct vm_event_state {
unsigned long event[NR_VM_EVENT_ITEMS];
};
DECLARE_PER_CPU(struct vm_event_state, vm_event_states);
/*
* vm counters are allowed to be racy. Use raw_cpu_ops to avoid the
* local_irq_disable overhead.
*/
static inline void __count_vm_event(enum vm_event_item item)
{
raw_cpu_inc(vm_event_states.event[item]);
}
static inline void count_vm_event(enum vm_event_item item)
{
this_cpu_inc(vm_event_states.event[item]);
}
static inline void __count_vm_events(enum vm_event_item item, long delta)
{
raw_cpu_add(vm_event_states.event[item], delta);
}
static inline void count_vm_events(enum vm_event_item item, long delta)
{
this_cpu_add(vm_event_states.event[item], delta);
}
extern void all_vm_events(unsigned long *);
extern void vm_events_fold_cpu(int cpu);
#else
/* Disable counters */
static inline void count_vm_event(enum vm_event_item item)
{
}
static inline void count_vm_events(enum vm_event_item item, long delta)
{
}
static inline void __count_vm_event(enum vm_event_item item)
{
}
static inline void __count_vm_events(enum vm_event_item item, long delta)
{
}
static inline void all_vm_events(unsigned long *ret)
{
}
static inline void vm_events_fold_cpu(int cpu)
{
}
#endif /* CONFIG_VM_EVENT_COUNTERS */
#ifdef CONFIG_NUMA_BALANCING
#define count_vm_numa_event(x) count_vm_event(x)
#define count_vm_numa_events(x, y) count_vm_events(x, y)
#else
#define count_vm_numa_event(x) do {} while (0)
#define count_vm_numa_events(x, y) do { (void)(y); } while (0)
#endif /* CONFIG_NUMA_BALANCING */
#ifdef CONFIG_DEBUG_TLBFLUSH
#define count_vm_tlb_event(x) count_vm_event(x)
#define count_vm_tlb_events(x, y) count_vm_events(x, y)
#else
#define count_vm_tlb_event(x) do {} while (0)
#define count_vm_tlb_events(x, y) do { (void)(y); } while (0)
#endif
#ifdef CONFIG_DEBUG_VM_VMACACHE
#define count_vm_vmacache_event(x) count_vm_event(x)
#else
#define count_vm_vmacache_event(x) do {} while (0)
#endif
#define __count_zid_vm_events(item, zid, delta) \
__count_vm_events(item##_NORMAL - ZONE_NORMAL + zid, delta)
/*
* 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];
#ifdef CONFIG_NUMA
static inline void zone_numa_state_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]);
}
static inline unsigned long global_numa_state(enum numa_stat_item item)
{
long x = atomic_long_read(&vm_numa_stat[item]);
return x;
}
static inline unsigned long zone_numa_state_snapshot(struct zone *zone,
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;
}
#endif /* CONFIG_NUMA */
static inline void zone_page_state_add(long x, struct zone *zone,
enum zone_stat_item item)
{
atomic_long_add(x, &zone->vm_stat[item]);
atomic_long_add(x, &vm_zone_stat[item]);
}
static inline void node_page_state_add(long x, struct pglist_data *pgdat,
enum node_stat_item item)
{
atomic_long_add(x, &pgdat->vm_stat[item]);
atomic_long_add(x, &vm_node_stat[item]);
}
static inline unsigned long global_zone_page_state(enum zone_stat_item item)
{
long x = atomic_long_read(&vm_zone_stat[item]);
#ifdef CONFIG_SMP
if (x < 0)
x = 0;
#endif
return x;
}
static inline
unsigned long global_node_page_state_pages(enum node_stat_item item)
{
long x = atomic_long_read(&vm_node_stat[item]);
#ifdef CONFIG_SMP
if (x < 0)
x = 0;
#endif
return x;
}
static inline unsigned long global_node_page_state(enum node_stat_item item)
{
VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
return global_node_page_state_pages(item);
}
static inline unsigned long zone_page_state(struct zone *zone,
enum zone_stat_item item)
{
long x = atomic_long_read(&zone->vm_stat[item]);
#ifdef CONFIG_SMP
if (x < 0)
x = 0;
#endif
return x;
}
/*
* More accurate version that also considers the currently pending
* deltas. For that we need to loop over all cpus to find the current
* deltas. There is no synchronization so the result cannot be
* exactly accurate either.
*/
static inline unsigned long zone_page_state_snapshot(struct zone *zone,
enum zone_stat_item item)
{
long x = atomic_long_read(&zone->vm_stat[item]);
#ifdef CONFIG_SMP
int cpu;
for_each_online_cpu(cpu)
x += per_cpu_ptr(zone->per_cpu_zonestats, cpu)->vm_stat_diff[item];
if (x < 0)
x = 0;
#endif
return x;
}
#ifdef CONFIG_NUMA
extern void __inc_numa_state(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 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);
#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)
#endif /* CONFIG_NUMA */
#ifdef CONFIG_SMP
void __mod_zone_page_state(struct zone *, enum zone_stat_item item, long);
void __inc_zone_page_state(struct page *, enum zone_stat_item);
void __dec_zone_page_state(struct page *, enum zone_stat_item);
void __mod_node_page_state(struct pglist_data *, enum node_stat_item item, long);
void __inc_node_page_state(struct page *, enum node_stat_item);
void __dec_node_page_state(struct page *, enum node_stat_item);
void mod_zone_page_state(struct zone *, enum zone_stat_item, long);
void inc_zone_page_state(struct page *, enum zone_stat_item);
void dec_zone_page_state(struct page *, enum zone_stat_item);
void mod_node_page_state(struct pglist_data *, enum node_stat_item, long);
void inc_node_page_state(struct page *, enum node_stat_item);
void dec_node_page_state(struct page *, enum node_stat_item);
extern void inc_node_state(struct pglist_data *, enum node_stat_item);
extern void __inc_zone_state(struct zone *, enum zone_stat_item);
extern void __inc_node_state(struct pglist_data *, enum node_stat_item);
extern void dec_zone_state(struct zone *, enum zone_stat_item);
extern void __dec_zone_state(struct zone *, enum zone_stat_item);
extern void __dec_node_state(struct pglist_data *, enum node_stat_item);
void quiet_vmstat(void);
void cpu_vm_stats_fold(int cpu);
void refresh_zone_stat_thresholds(void);
struct ctl_table;
int vmstat_refresh(struct ctl_table *, int write, void *buffer, size_t *lenp,
loff_t *ppos);
void drain_zonestat(struct zone *zone, struct per_cpu_zonestat *);
int calculate_pressure_threshold(struct zone *zone);
int calculate_normal_threshold(struct zone *zone);
void set_pgdat_percpu_threshold(pg_data_t *pgdat,
int (*calculate_pressure)(struct zone *));
#else /* CONFIG_SMP */
/*
* We do not maintain differentials in a single processor configuration.
* The functions directly modify the zone and global counters.
*/
static inline void __mod_zone_page_state(struct zone *zone,
enum zone_stat_item item, long delta)
{
zone_page_state_add(delta, zone, item);
}
static inline void __mod_node_page_state(struct pglist_data *pgdat,
enum node_stat_item item, int delta)
{
if (vmstat_item_in_bytes(item)) {
/*
* Only cgroups use subpage accounting right now; at
* the global level, these items still change in
* multiples of whole pages. Store them as pages
* internally to keep the per-cpu counters compact.
*/
VM_WARN_ON_ONCE(delta & (PAGE_SIZE - 1));
delta >>= PAGE_SHIFT;
}
node_page_state_add(delta, pgdat, item);
}
static inline void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
{
atomic_long_inc(&zone->vm_stat[item]);
atomic_long_inc(&vm_zone_stat[item]);
}
static inline void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
{
atomic_long_inc(&pgdat->vm_stat[item]);
atomic_long_inc(&vm_node_stat[item]);
}
static inline void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
{
atomic_long_dec(&zone->vm_stat[item]);
atomic_long_dec(&vm_zone_stat[item]);
}
static inline void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
{
atomic_long_dec(&pgdat->vm_stat[item]);
atomic_long_dec(&vm_node_stat[item]);
}
static inline void __inc_zone_page_state(struct page *page,
enum zone_stat_item item)
{
__inc_zone_state(page_zone(page), item);
}
static inline void __inc_node_page_state(struct page *page,
enum node_stat_item item)
{
__inc_node_state(page_pgdat(page), item);
}
static inline void __dec_zone_page_state(struct page *page,
enum zone_stat_item item)
{
__dec_zone_state(page_zone(page), item);
}
static inline void __dec_node_page_state(struct page *page,
enum node_stat_item item)
{
__dec_node_state(page_pgdat(page), item);
}
/*
* We only use atomic operations to update counters. So there is no need to
* disable interrupts.
*/
#define inc_zone_page_state __inc_zone_page_state
#define dec_zone_page_state __dec_zone_page_state
#define mod_zone_page_state __mod_zone_page_state
#define inc_node_page_state __inc_node_page_state
#define dec_node_page_state __dec_node_page_state
#define mod_node_page_state __mod_node_page_state
#define inc_zone_state __inc_zone_state
#define inc_node_state __inc_node_state
#define dec_zone_state __dec_zone_state
#define set_pgdat_percpu_threshold(pgdat, callback) { }
static inline void refresh_zone_stat_thresholds(void) { }
static inline void cpu_vm_stats_fold(int cpu) { }
static inline void quiet_vmstat(void) { }
static inline void drain_zonestat(struct zone *zone,
struct per_cpu_zonestat *pzstats) { }
#endif /* CONFIG_SMP */
static inline void __mod_zone_freepage_state(struct zone *zone, int nr_pages,
int migratetype)
{
__mod_zone_page_state(zone, NR_FREE_PAGES, nr_pages);
if (is_migrate_cma(migratetype))
__mod_zone_page_state(zone, NR_FREE_CMA_PAGES, nr_pages);
}
extern const char * const vmstat_text[];
static inline const char *zone_stat_name(enum zone_stat_item item)
{
return vmstat_text[item];
}
#ifdef CONFIG_NUMA
static inline const char *numa_stat_name(enum numa_stat_item item)
{
return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
item];
}
#endif /* CONFIG_NUMA */
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 +
item];
}
static inline const char *lru_list_name(enum lru_list lru)
{
return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
}
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_NODE_STAT_ITEMS +
item];
}
#if defined(CONFIG_VM_EVENT_COUNTERS) || defined(CONFIG_MEMCG)
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_NODE_STAT_ITEMS +
NR_VM_WRITEBACK_STAT_ITEMS +
item];
}
#endif /* CONFIG_VM_EVENT_COUNTERS || CONFIG_MEMCG */
#ifdef CONFIG_MEMCG
void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
int val);
static inline void mod_lruvec_state(struct lruvec *lruvec,
enum node_stat_item idx, int val)
{
unsigned long flags;
local_irq_save(flags);
__mod_lruvec_state(lruvec, idx, val);
local_irq_restore(flags);
}
void __mod_lruvec_page_state(struct page *page,
enum node_stat_item idx, int val);
static inline void mod_lruvec_page_state(struct page *page,
enum node_stat_item idx, int val)
{
unsigned long flags;
local_irq_save(flags);
__mod_lruvec_page_state(page, idx, val);
local_irq_restore(flags);
}
#else
static inline void __mod_lruvec_state(struct lruvec *lruvec,
enum node_stat_item idx, int val)
{
__mod_node_page_state(lruvec_pgdat(lruvec), idx, val);
}
static inline void mod_lruvec_state(struct lruvec *lruvec,
enum node_stat_item idx, int val)
{
mod_node_page_state(lruvec_pgdat(lruvec), idx, val);
}
static inline void __mod_lruvec_page_state(struct page *page,
enum node_stat_item idx, int val)
{
__mod_node_page_state(page_pgdat(page), idx, val);
}
static inline void mod_lruvec_page_state(struct page *page,
enum node_stat_item idx, int val)
{
mod_node_page_state(page_pgdat(page), idx, val);
}
#endif /* CONFIG_MEMCG */
static inline void inc_lruvec_state(struct lruvec *lruvec,
enum node_stat_item idx)
{
mod_lruvec_state(lruvec, idx, 1);
}
static inline void __inc_lruvec_page_state(struct page *page,
enum node_stat_item idx)
{
__mod_lruvec_page_state(page, idx, 1);
}
static inline void __dec_lruvec_page_state(struct page *page,
enum node_stat_item idx)
{
__mod_lruvec_page_state(page, idx, -1);
}
static inline void inc_lruvec_page_state(struct page *page,
enum node_stat_item idx)
{
mod_lruvec_page_state(page, idx, 1);
}
static inline void dec_lruvec_page_state(struct page *page,
enum node_stat_item idx)
{
mod_lruvec_page_state(page, idx, -1);
}
#endif /* _LINUX_VMSTAT_H */