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| author | Mikulas Patocka <mpatocka@redhat.com> | 2013-08-16 16:54:23 +0200 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2013-09-06 02:46:06 +0200 |
| commit | fd2ed4d252701d3bbed4cd3e3d267ad469bb832a (patch) | |
| tree | 264ff043406894bd447eb6e9976b9a2b4d69bd9f /drivers/md/dm.h | |
| parent | dm thin: always return -ENOSPC if no_free_space is set (diff) | |
| download | linux-fd2ed4d252701d3bbed4cd3e3d267ad469bb832a.tar.xz linux-fd2ed4d252701d3bbed4cd3e3d267ad469bb832a.zip | |
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 <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm.h')
| -rw-r--r-- | drivers/md/dm.h | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 8b4c075d9a2f..5e604cc7b4aa 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -16,6 +16,8 @@ #include <linux/blkdev.h> #include <linux/hdreg.h> +#include "dm-stats.h" + /* * Suspend feature flags */ @@ -157,10 +159,16 @@ void dm_destroy(struct mapped_device *md); void dm_destroy_immediate(struct mapped_device *md); int dm_open_count(struct mapped_device *md); int dm_lock_for_deletion(struct mapped_device *md); +int dm_request_based(struct mapped_device *md); +sector_t dm_get_size(struct mapped_device *md); +struct dm_stats *dm_get_stats(struct mapped_device *md); int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action, unsigned cookie); +void dm_internal_suspend(struct mapped_device *md); +void dm_internal_resume(struct mapped_device *md); + int dm_io_init(void); void dm_io_exit(void); @@ -173,4 +181,12 @@ void dm_kcopyd_exit(void); struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, unsigned per_bio_data_size); void dm_free_md_mempools(struct dm_md_mempools *pools); +/* + * Helpers that are used by DM core + */ +static inline bool dm_message_test_buffer_overflow(char *result, unsigned maxlen) +{ + return !maxlen || strlen(result) + 1 >= maxlen; +} + #endif |