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.
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| @@ -267,9 +267,9 @@ enum { · 266 unmodified lines | |||
| 267 | #define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl) | 267 | #define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl) |
| 268 | 268 | ||
| 269 | #define DM_VERSION_MAJOR 4 | 269 | #define DM_VERSION_MAJOR 4 |
| 270 | #define DM_VERSION_MINOR 25 | 270 | #define DM_VERSION_MINOR 26 |
| 271 | #define DM_VERSION_PATCHLEVEL 0 | 271 | #define DM_VERSION_PATCHLEVEL 0 |
| 272 | #define DM_VERSION_EXTRA "-ioctl (2013-06-26)" | 272 | #define DM_VERSION_EXTRA "-ioctl (2013-08-15)" |
| 273 | 273 | ||
| 274 | /* Status bits */ | 274 | /* Status bits */ |
| 275 | #define DM_READONLY_FLAG (1 << 0) /* In/Out */ | 275 | #define DM_READONLY_FLAG (1 << 0) /* In/Out */ |