Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) =============
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) DM statistics
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3) =============
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5) Device Mapper supports the collection of I/O statistics on user-defined
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6) regions of a DM device.	 If no regions are defined no statistics are
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7) collected so there isn't any performance impact.  Only bio-based DM
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8) devices are currently supported.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10) Each user-defined region specifies a starting sector, length and step.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11) Individual statistics will be collected for each step-sized area within
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12) the range specified.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14) The I/O statistics counters for each step-sized area of a region are
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15) in the same format as `/sys/block/*/stat` or `/proc/diskstats` (see:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16) Documentation/admin-guide/iostats.rst).  But two extra counters (12 and 13) are
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17) provided: total time spent reading and writing.  When the histogram
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18) argument is used, the 14th parameter is reported that represents the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19) histogram of latencies.  All these counters may be accessed by sending
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20) the @stats_print message to the appropriate DM device via dmsetup.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22) The reported times are in milliseconds and the granularity depends on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23) the kernel ticks.  When the option precise_timestamps is used, the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24) reported times are in nanoseconds.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26) Each region has a corresponding unique identifier, which we call a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27) region_id, that is assigned when the region is created.	 The region_id
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28) must be supplied when querying statistics about the region, deleting the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29) region, etc.  Unique region_ids enable multiple userspace programs to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30) request and process statistics for the same DM device without stepping
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31) on each other's data.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33) The creation of DM statistics will allocate memory via kmalloc or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) fallback to using vmalloc space.  At most, 1/4 of the overall system
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) memory may be allocated by DM statistics.  The admin can see how much
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) memory is used by reading:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) 	/sys/module/dm_mod/parameters/stats_current_allocated_bytes
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) Messages
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) ========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43)     @stats_create <range> <step> [<number_of_optional_arguments> <optional_arguments>...] [<program_id> [<aux_data>]]
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44) 	Create a new region and return the region_id.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46) 	<range>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47) 	  "-"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48) 		whole device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49) 	  "<start_sector>+<length>"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50) 		a range of <length> 512-byte sectors
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51) 		starting with <start_sector>.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53) 	<step>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54) 	  "<area_size>"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55) 		the range is subdivided into areas each containing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56) 		<area_size> sectors.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57) 	  "/<number_of_areas>"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58) 		the range is subdivided into the specified
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59) 		number of areas.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61) 	<number_of_optional_arguments>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62) 	  The number of optional arguments
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64) 	<optional_arguments>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65) 	  The following optional arguments are supported:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) 	  precise_timestamps
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) 		use precise timer with nanosecond resolution
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) 		instead of the "jiffies" variable.  When this argument is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70) 		used, the resulting times are in nanoseconds instead of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71) 		milliseconds.  Precise timestamps are a little bit slower
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72) 		to obtain than jiffies-based timestamps.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73) 	  histogram:n1,n2,n3,n4,...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74) 		collect histogram of latencies.  The
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75) 		numbers n1, n2, etc are times that represent the boundaries
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76) 		of the histogram.  If precise_timestamps is not used, the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77) 		times are in milliseconds, otherwise they are in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78) 		nanoseconds.  For each range, the kernel will report the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79) 		number of requests that completed within this range. For
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80) 		example, if we use "histogram:10,20,30", the kernel will
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81) 		report four numbers a:b:c:d. a is the number of requests
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82) 		that took 0-10 ms to complete, b is the number of requests
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83) 		that took 10-20 ms to complete, c is the number of requests
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84) 		that took 20-30 ms to complete and d is the number of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85) 		requests that took more than 30 ms to complete.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87) 	<program_id>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88) 	  An optional parameter.  A name that uniquely identifies
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) 	  the userspace owner of the range.  This groups ranges together
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) 	  so that userspace programs can identify the ranges they
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) 	  created and ignore those created by others.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) 	  The kernel returns this string back in the output of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) 	  @stats_list message, but it doesn't use it for anything else.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) 	  If we omit the number of optional arguments, program id must not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95) 	  be a number, otherwise it would be interpreted as the number of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96) 	  optional arguments.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98) 	<aux_data>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99) 	  An optional parameter.  A word that provides auxiliary data
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) 	  that is useful to the client program that created the range.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) 	  The kernel returns this string back in the output of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) 	  @stats_list message, but it doesn't use this value for anything.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104)     @stats_delete <region_id>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) 	Delete the region with the specified id.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) 	<region_id>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) 	  region_id returned from @stats_create
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110)     @stats_clear <region_id>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) 	Clear all the counters except the in-flight i/o counters.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) 	<region_id>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) 	  region_id returned from @stats_create
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116)     @stats_list [<program_id>]
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) 	List all regions registered with @stats_create.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) 	<program_id>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) 	  An optional parameter.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) 	  If this parameter is specified, only matching regions
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) 	  are returned.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) 	  If it is not specified, all regions are returned.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) 	Output format:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) 	  <region_id>: <start_sector>+<length> <step> <program_id> <aux_data>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) 	        precise_timestamps histogram:n1,n2,n3,...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) 	The strings "precise_timestamps" and "histogram" are printed only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) 	if they were specified when creating the region.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132)     @stats_print <region_id> [<starting_line> <number_of_lines>]
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) 	Print counters for each step-sized area of a region.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) 	<region_id>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) 	  region_id returned from @stats_create
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) 	<starting_line>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) 	  The index of the starting line in the output.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) 	  If omitted, all lines are returned.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) 	<number_of_lines>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) 	  The number of lines to include in the output.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) 	  If omitted, all lines are returned.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) 	Output format for each step-sized area of a region:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) 	  <start_sector>+<length>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) 		counters
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) 	  The first 11 counters have the same meaning as
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) 	  `/sys/block/*/stat or /proc/diskstats`.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) 	  Please refer to Documentation/admin-guide/iostats.rst for details.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) 	  1. the number of reads completed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) 	  2. the number of reads merged
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) 	  3. the number of sectors read
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) 	  4. the number of milliseconds spent reading
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) 	  5. the number of writes completed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) 	  6. the number of writes merged
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) 	  7. the number of sectors written
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) 	  8. the number of milliseconds spent writing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) 	  9. the number of I/Os currently in progress
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) 	  10. the number of milliseconds spent doing I/Os
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) 	  11. the weighted number of milliseconds spent doing I/Os
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) 	  Additional counters:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) 	  12. the total time spent reading in milliseconds
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) 	  13. the total time spent writing in milliseconds
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173)     @stats_print_clear <region_id> [<starting_line> <number_of_lines>]
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) 	Atomically print and then clear all the counters except the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) 	in-flight i/o counters.	 Useful when the client consuming the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) 	statistics does not want to lose any statistics (those updated
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) 	between printing and clearing).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) 	<region_id>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) 	  region_id returned from @stats_create
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) 	<starting_line>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) 	  The index of the starting line in the output.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) 	  If omitted, all lines are printed and then cleared.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) 	<number_of_lines>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) 	  The number of lines to process.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) 	  If omitted, all lines are printed and then cleared.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190)     @stats_set_aux <region_id> <aux_data>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) 	Store auxiliary data aux_data for the specified region.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) 	<region_id>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) 	  region_id returned from @stats_create
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) 	<aux_data>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) 	  The string that identifies data which is useful to the client
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) 	  program that created the range.  The kernel returns this
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) 	  string back in the output of @stats_list message, but it
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) 	  doesn't use this value for anything.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) Examples
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) ========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) Subdivide the DM device 'vol' into 100 pieces and start collecting
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) statistics on them::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208)   dmsetup message vol 0 @stats_create - /100
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) Set the auxiliary data string to "foo bar baz" (the escape for each
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) space must also be escaped, otherwise the shell will consume them)::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213)   dmsetup message vol 0 @stats_set_aux 0 foo\\ bar\\ baz
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) List the statistics::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217)   dmsetup message vol 0 @stats_list
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) Print the statistics::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221)   dmsetup message vol 0 @stats_print 0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) Delete the statistics::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225)   dmsetup message vol 0 @stats_delete 0