diff options
-rw-r--r-- | include/linux/backing-dev.h | 85 | ||||
-rw-r--r-- | mm/backing-dev.c | 27 |
2 files changed, 109 insertions, 3 deletions
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 8f56634f537..f7677ff80cc 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -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 } /* diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 841901a9559..a47065e084a 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -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]) |