Hello Bryn, Thanks much for clarification ! Regards, Asha -----Original Message----- From: Bryn M. Reeves [mailto:bmr@xxxxxxxxxx] Sent: Wednesday, January 04, 2017 5:04 PM To: A M, Ashalatha <ashalatha-a.a@xxxxxxx> Cc: dm-devel@xxxxxxxxxx Subject: Re: dm stats On Wed, Dec 21, 2016 at 10:49:06AM +0000, A M, Ashalatha wrote: > In this documentation, would like to know what is the command to be used to create/print/list stats. > > @stats_create <range> <step> [<program_id> [<aux_data>]] > > @stats_print <region_id> [<starting_line> <number_of_lines>] > > @stats_list [<program_id>] These are device-mapper messages that you can send to a device to create, print, or list statistics regions. All range and step arguments are in sectors and the messages are issued with the 'dmsetup message' command. For example: # dmsetup message vg_hex/root 0 "@stats_list" 0: 35325952+2048 2048 dmstats - 1: 35325952+2048 2048 dmstats - 2: 44908544+16384 16384 dmstats DMS_GROUP=vm.img:2#- This is however a very low-level interface to the dmstats facility; users are encouraged to use the userspace library (part of libdevmapper - see libdevmapper.h for API documentation), or the 'dmstats' command to manage device-mapper statistics. # dmstats list Name GrpID RgID ObjType RgStart RgSize #Areas ArSize ProgID vg_hex-root - 0 region 16.84g 1.00m 1 1.00m dmstats vg_hex-root - 1 region 16.84g 1.00m 1 1.00m dmstats vm.img 2 2 region 21.41g 8.00m 1 8.00m dmstats This has the benefit of a simpler command interface, automatic rate conversion for derived metrics (MB/s, queue length, etc.), configurable time and size units, flexible field control, grouping, aliasing and many other convenient features - see man 8 dmstats for further details of the command interface. > Also, it is documented that 11 stats(Documentation/iostats.txt) would be reported and additional counters as well: > > 12. the total time spent reading in milliseconds > > 13. the total time spent writing in milliseconds > > So are these same as "read_ticks" and "write_ticks" else how different from the ticks? Yes: these are the fields reported by dmstats as 'read_ticks' and 'write_ticks'. They differ from 'read_time' and 'write_time' in that they are the time spent _servicing_ (i.e. actively processing) read and write requests - the two '_time' fields instead track the total accumulated time for all requests (the time from the request being submitted to the time when it is completed, summed for all requests). Regards, Bryn. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
