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authorMikulas Patocka <mpatocka@redhat.com>2013-08-16 16:54:23 +0200
committerMike Snitzer <snitzer@redhat.com>2013-09-06 02:46:06 +0200
commitfd2ed4d252701d3bbed4cd3e3d267ad469bb832a (patch)
tree264ff043406894bd447eb6e9976b9a2b4d69bd9f /drivers/md/dm-stats.h
parentdm thin: always return -ENOSPC if no_free_space is set (diff)
downloadlinux-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-stats.h')
-rw-r--r--drivers/md/dm-stats.h40
1 files changed, 40 insertions, 0 deletions
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 <linux/types.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+
+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