Provide scalable per backing_dev_info statistics counters. Signed-off-by: Peter Zijlstra --- include/linux/backing-dev.h | 96 +++++++++++++++++++++++++++++++++++++++++++- mm/backing-dev.c | 21 +++++++++ 2 files changed, 115 insertions(+), 2 deletions(-) Index: linux-2.6/include/linux/backing-dev.h =================================================================== --- linux-2.6.orig/include/linux/backing-dev.h 2007-05-10 10:21:53.000000000 +0200 +++ linux-2.6/include/linux/backing-dev.h 2007-05-10 10:23:26.000000000 +0200 @@ -8,6 +8,8 @@ #ifndef _LINUX_BACKING_DEV_H #define _LINUX_BACKING_DEV_H +#include +#include #include 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 */ @@ -32,14 +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 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, BDI_STAT_BATCH); +} + +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 bdi_destroy(struct backing_dev_info *bdi) +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(&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 } /* Index: linux-2.6/mm/backing-dev.c =================================================================== --- linux-2.6.orig/mm/backing-dev.c 2007-05-10 10:21:46.000000000 +0200 +++ linux-2.6/mm/backing-dev.c 2007-05-10 10:23:08.000000000 +0200 @@ -5,6 +5,24 @@ #include #include +void bdi_init(struct backing_dev_info *bdi) +{ + int i; + + for (i = 0; i < NR_BDI_STAT_ITEMS; i++) + percpu_counter_init_irq(&bdi->bdi_stat[i], 0); +} +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]) -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/