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mm: scalable bdi statistics counters 

Provide scalable per backing_dev_info statistics counters.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Peter Zijlstra 2007-10-16 23:25:47 -07:00 committed by Linus Torvalds
parent e0bf68ddec
commit b2e8fb6efa
2 changed files with 109 additions and 3 deletions
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85
include/linux/backing-dev.h
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@ -8,6 +8,8 @@
#ifndef _LINUX_BACKING_DEV_H
#define _LINUX_BACKING_DEV_H
#include <linux/percpu_counter.h>
#include <linux/log2.h>
#include <asm/atomic.h>
struct page;
@ -24,6 +26,12 @@ enum bdi_state {
typedef int (congested_fn)(void *, int);
enum bdi_stat_item {
NR_BDI_STAT_ITEMS
};
#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
struct backing_dev_info {
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned long state; /* Always use atomic bitops on this */
@ -32,15 +40,86 @@ struct backing_dev_info {
void *congested_data; /* Pointer to aux data for congested func */
void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
void *unplug_io_data;
struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
};
static inline int bdi_init(struct backing_dev_info *bdi)
int bdi_init(struct backing_dev_info *bdi);
void bdi_destroy(struct backing_dev_info *bdi);
static inline void __add_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item, s64 amount)
{
return 0;
__percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
}
static inline void bdi_destroy(struct backing_dev_info *bdi)
static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item)
{
__add_bdi_stat(bdi, item, 1);
}
static inline void inc_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item)
{
unsigned long flags;
local_irq_save(flags);
__inc_bdi_stat(bdi, item);
local_irq_restore(flags);
}
static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item)
{
__add_bdi_stat(bdi, item, -1);
}
static inline void dec_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item)
{
unsigned long flags;
local_irq_save(flags);
__dec_bdi_stat(bdi, item);
local_irq_restore(flags);
}
static inline s64 bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item)
{
return percpu_counter_read_positive(&bdi->bdi_stat[item]);
}
static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
enum bdi_stat_item item)
{
return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
}
static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
enum bdi_stat_item item)
{
s64 sum;
unsigned long flags;
local_irq_save(flags);
sum = __bdi_stat_sum(bdi, item);
local_irq_restore(flags);
return sum;
}
/*
* maximal error of a stat counter.
*/
static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
{
#ifdef CONFIG_SMP
return nr_cpu_ids * BDI_STAT_BATCH;
#else
return 1;
#endif
}
/*

27
mm/backing-dev.c
View File

@ -5,6 +5,33 @@
#include <linux/sched.h>
#include <linux/module.h>
int bdi_init(struct backing_dev_info *bdi)
{
int i, j;
int err;
for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
if (err) {
for (j = 0; j < i; j++)
percpu_counter_destroy(&bdi->bdi_stat[i]);
break;
}
}
return err;
}
EXPORT_SYMBOL(bdi_init);
void bdi_destroy(struct backing_dev_info *bdi)
{
int i;
for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
percpu_counter_destroy(&bdi->bdi_stat[i]);
}
EXPORT_SYMBOL(bdi_destroy);
static wait_queue_head_t congestion_wqh[2] = {
__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])