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authorMikulas Patocka <mpatocka@redhat.com>2013-08-16 10:54:23 -0400
committerMike Snitzer <snitzer@redhat.com>2013-09-05 20:46:06 -0400
commitfd2ed4d252701d3bbed4cd3e3d267ad469bb832a (patch)
tree264ff043406894bd447eb6e9976b9a2b4d69bd9f /include/linux/device-mapper.h
parent94563badaf41f9291ff0bad94a443a4319b9e312 (diff)
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 'include/linux/device-mapper.h')
-rw-r--r--include/linux/device-mapper.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index e151d4c9298d..653073de09e3 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -10,6 +10,7 @@
#include <linux/bio.h>
#include <linux/blkdev.h>
+#include <linux/math64.h>
#include <linux/ratelimit.h>
struct dm_dev;
@@ -550,6 +551,14 @@ extern struct ratelimit_state dm_ratelimit_state;
#define DM_MAPIO_REMAPPED 1
#define DM_MAPIO_REQUEUE DM_ENDIO_REQUEUE
+#define dm_sector_div64(x, y)( \
+{ \
+ u64 _res; \
+ (x) = div64_u64_rem(x, y, &_res); \
+ _res; \
+} \
+)
+
/*
* Ceiling(n / sz)
*/