![Peter Zijlstra](/assets/img/avatar_default.png)
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>
198 lines
5.5 KiB
C
198 lines
5.5 KiB
C
/*
|
|
* include/linux/backing-dev.h
|
|
*
|
|
* low-level device information and state which is propagated up through
|
|
* to high-level code.
|
|
*/
|
|
|
|
#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;
|
|
|
|
/*
|
|
* Bits in backing_dev_info.state
|
|
*/
|
|
enum bdi_state {
|
|
BDI_pdflush, /* A pdflush thread is working this device */
|
|
BDI_write_congested, /* The write queue is getting full */
|
|
BDI_read_congested, /* The read queue is getting full */
|
|
BDI_unused, /* Available bits start here */
|
|
};
|
|
|
|
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 */
|
|
unsigned int capabilities; /* Device capabilities */
|
|
congested_fn *congested_fn; /* Function pointer if device is md/dm */
|
|
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];
|
|
};
|
|
|
|
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)
|
|
{
|
|
__percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
|
|
}
|
|
|
|
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
|
|
}
|
|
|
|
/*
|
|
* Flags in backing_dev_info::capability
|
|
* - The first two flags control whether dirty pages will contribute to the
|
|
* VM's accounting and whether writepages() should be called for dirty pages
|
|
* (something that would not, for example, be appropriate for ramfs)
|
|
* - These flags let !MMU mmap() govern direct device mapping vs immediate
|
|
* copying more easily for MAP_PRIVATE, especially for ROM filesystems
|
|
*/
|
|
#define BDI_CAP_NO_ACCT_DIRTY 0x00000001 /* Dirty pages shouldn't contribute to accounting */
|
|
#define BDI_CAP_NO_WRITEBACK 0x00000002 /* Don't write pages back */
|
|
#define BDI_CAP_MAP_COPY 0x00000004 /* Copy can be mapped (MAP_PRIVATE) */
|
|
#define BDI_CAP_MAP_DIRECT 0x00000008 /* Can be mapped directly (MAP_SHARED) */
|
|
#define BDI_CAP_READ_MAP 0x00000010 /* Can be mapped for reading */
|
|
#define BDI_CAP_WRITE_MAP 0x00000020 /* Can be mapped for writing */
|
|
#define BDI_CAP_EXEC_MAP 0x00000040 /* Can be mapped for execution */
|
|
#define BDI_CAP_VMFLAGS \
|
|
(BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
|
|
|
|
#if defined(VM_MAYREAD) && \
|
|
(BDI_CAP_READ_MAP != VM_MAYREAD || \
|
|
BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
|
|
BDI_CAP_EXEC_MAP != VM_MAYEXEC)
|
|
#error please change backing_dev_info::capabilities flags
|
|
#endif
|
|
|
|
extern struct backing_dev_info default_backing_dev_info;
|
|
void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
|
|
|
|
int writeback_acquire(struct backing_dev_info *bdi);
|
|
int writeback_in_progress(struct backing_dev_info *bdi);
|
|
void writeback_release(struct backing_dev_info *bdi);
|
|
|
|
static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
|
|
{
|
|
if (bdi->congested_fn)
|
|
return bdi->congested_fn(bdi->congested_data, bdi_bits);
|
|
return (bdi->state & bdi_bits);
|
|
}
|
|
|
|
static inline int bdi_read_congested(struct backing_dev_info *bdi)
|
|
{
|
|
return bdi_congested(bdi, 1 << BDI_read_congested);
|
|
}
|
|
|
|
static inline int bdi_write_congested(struct backing_dev_info *bdi)
|
|
{
|
|
return bdi_congested(bdi, 1 << BDI_write_congested);
|
|
}
|
|
|
|
static inline int bdi_rw_congested(struct backing_dev_info *bdi)
|
|
{
|
|
return bdi_congested(bdi, (1 << BDI_read_congested)|
|
|
(1 << BDI_write_congested));
|
|
}
|
|
|
|
void clear_bdi_congested(struct backing_dev_info *bdi, int rw);
|
|
void set_bdi_congested(struct backing_dev_info *bdi, int rw);
|
|
long congestion_wait(int rw, long timeout);
|
|
|
|
#define bdi_cap_writeback_dirty(bdi) \
|
|
(!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK))
|
|
|
|
#define bdi_cap_account_dirty(bdi) \
|
|
(!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY))
|
|
|
|
#define mapping_cap_writeback_dirty(mapping) \
|
|
bdi_cap_writeback_dirty((mapping)->backing_dev_info)
|
|
|
|
#define mapping_cap_account_dirty(mapping) \
|
|
bdi_cap_account_dirty((mapping)->backing_dev_info)
|
|
|
|
|
|
#endif /* _LINUX_BACKING_DEV_H */
|