From fd2ed4d252701d3bbed4cd3e3d267ad469bb832a Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Fri, 16 Aug 2013 10:54:23 -0400 Subject: dm: add statistics support Support the collection of I/O statistics on user-defined regions of a DM device. If no regions are defined no statistics are collected so there isn't any performance impact. Only bio-based DM devices are currently supported. Each user-defined region specifies a starting sector, length and step. Individual statistics will be collected for each step-sized area within the range specified. The I/O statistics counters for each step-sized area of a region are in the same format as /sys/block/*/stat or /proc/diskstats but extra counters (12 and 13) are provided: total time spent reading and writing in milliseconds. All these counters may be accessed by sending the @stats_print message to the appropriate DM device via dmsetup. The creation of DM statistics will allocate memory via kmalloc or fallback to using vmalloc space. At most, 1/4 of the overall system memory may be allocated by DM statistics. The admin can see how much memory is used by reading /sys/module/dm_mod/parameters/stats_current_allocated_bytes See Documentation/device-mapper/statistics.txt for more details. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- drivers/md/dm-stats.h | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 drivers/md/dm-stats.h (limited to 'drivers/md/dm-stats.h') diff --git a/drivers/md/dm-stats.h b/drivers/md/dm-stats.h new file mode 100644 index 000000000000..e7c4984bf235 --- /dev/null +++ b/drivers/md/dm-stats.h @@ -0,0 +1,40 @@ +#ifndef DM_STATS_H +#define DM_STATS_H + +#include +#include +#include + +int dm_statistics_init(void); +void dm_statistics_exit(void); + +struct dm_stats { + struct mutex mutex; + struct list_head list; /* list of struct dm_stat */ + struct dm_stats_last_position __percpu *last; + sector_t last_sector; + unsigned last_rw; +}; + +struct dm_stats_aux { + bool merged; +}; + +void dm_stats_init(struct dm_stats *st); +void dm_stats_cleanup(struct dm_stats *st); + +struct mapped_device; + +int dm_stats_message(struct mapped_device *md, unsigned argc, char **argv, + char *result, unsigned maxlen); + +void dm_stats_account_io(struct dm_stats *stats, unsigned long bi_rw, + sector_t bi_sector, unsigned bi_sectors, bool end, + unsigned long duration, struct dm_stats_aux *aux); + +static inline bool dm_stats_used(struct dm_stats *st) +{ + return !list_empty(&st->list); +} + +#endif -- cgit