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Subject[PATCH 06/12] mm: scalable bdi statistics counters.
Provide scalable per backing_dev_info statistics counters.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/linux/backing-dev.h | 50 ++++++++++++++++++++++++++++++++++++++++++--
mm/backing-dev.c | 26 ++++++++++++++++++++++
2 files changed, 74 insertions(+), 2 deletions(-)
Index: linux-2.6/include/linux/backing-dev.h
===================================================================
--- linux-2.6.orig/include/linux/backing-dev.h 2007-04-12 13:27:13.000000000 +0200
+++ linux-2.6/include/linux/backing-dev.h 2007-04-12 13:28:40.000000000 +0200
@@ -8,6 +8,7 @@
#ifndef _LINUX_BACKING_DEV_H
#define _LINUX_BACKING_DEV_H

+#include <linux/percpu_counter.h>
#include <asm/atomic.h>

struct page;
@@ -24,6 +25,10 @@ enum bdi_state {

typedef int (congested_fn)(void *, int);

+enum bdi_stat_item {
+ NR_BDI_STAT_ITEMS
+};
+
struct backing_dev_info {
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned long ra_pages0; /* min readahead on start of file */
@@ -34,14 +39,55 @@ 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 void bdi_init(struct backing_dev_info *bdi)
+void bdi_init(struct backing_dev_info *bdi);
+void bdi_destroy(struct backing_dev_info *bdi);
+
+static inline void __mod_bdi_stat(struct backing_dev_info *bdi,
+ enum bdi_stat_item item, s32 amount)
+{
+ percpu_counter_mod(&bdi->bdi_stat[item], amount);
+}
+
+static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
+ enum bdi_stat_item item)
+{
+ __mod_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)
{
+ __mod_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 void bdi_destroy(struct backing_dev_info *bdi)
+static inline s64 bdi_stat(struct backing_dev_info *bdi,
+ enum bdi_stat_item item)
{
+ return percpu_counter_read_positive(&bdi->bdi_stat[item]);
}

/*
Index: linux-2.6/mm/backing-dev.c
===================================================================
--- linux-2.6.orig/mm/backing-dev.c 2007-04-12 13:27:10.000000000 +0200
+++ linux-2.6/mm/backing-dev.c 2007-04-12 13:28:26.000000000 +0200
@@ -5,6 +5,30 @@
#include <linux/sched.h>
#include <linux/module.h>

+void bdi_init(struct backing_dev_info *bdi)
+{
+ int i;
+
+ if (!(bdi_cap_writeback_dirty(bdi) || bdi_cap_account_dirty(bdi)))
+ return;
+
+ for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
+ percpu_counter_init(&bdi->bdi_stat[i], 0);
+}
+EXPORT_SYMBOL(bdi_init);
+
+void bdi_destroy(struct backing_dev_info *bdi)
+{
+ int i;
+
+ if (!(bdi_cap_writeback_dirty(bdi) || bdi_cap_account_dirty(bdi)))
+ return;
+
+ 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])
@@ -70,3 +94,5 @@ long congestion_wait_interruptible(int r
return ret;
}
EXPORT_SYMBOL(congestion_wait_interruptible);
+
+
--

-
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