btt(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | AUTHORS | REPORTING BUGS | COPYRIGHT | SEE ALSO | COLOPHON

BTT(1)                                                            BTT(1)

NAME         top

       btt - analyse block i/o traces produces by blktrace

SYNOPSIS         top

       btt
       [ -a               | --seek-absolute ]
       [ -A               | --all-data ]
       [ -B <output name> | --dump-blocknos=<output name> ]
       [ -d <seconds>     | --range-delta=<seconds> ]
       [ -D <dev;...>     | --devices=<dev;...> ]
       [ -e <exe,...>     | --exes=<exe,...>  ]
       [ -h               | --help ]
       [ -i <input name>  | --input-file=<input name> ]
       [ -I <output name> | --iostat=<output name> ]
       [ -l <output name> | --d2c-latencies=<output name> ]
       [ -L <freq>        | --periodic-latencies=<freq> ]
       [ -m <output name> | --seeks-per-second=<output name> ]
       [ -M <dev map>     | --dev-maps=<dev map>
       [ -o <output name> | --output-file=<output name> ]
       [ -p <output name> | --per-io-dump=<output name> ]
       [ -P <output name> | --per-io-trees=<output name> ]
       [ -q <output name> | --q2c-latencies=<output name> ]
       [ -Q <output name> | --active-queue-depth=<output name> ]
       [ -r               | --no-remaps ]
       [ -s <output name> | --seeks=<output name> ]
       [ -S <interval>    | --iostat-interval=<interval> ]
       [ -t <sec>         | --time-start=<sec> ]
       [ -T <sec>         | --time-end=<sec> ]
       [ -u <output name> | --unplug-hist=<output name> ]
       [ -v               | --verbose ]
       [ -V               | --version ]
       [ -X               | --easy-parse-avgs ]
       [ -z <output name> | --q2d-latencies=<output name> ]
       [ -Z               | --do-active ]

DESCRIPTION         top

       btt is a post-processing tool for the block layer IO tracing tool
       called blktrace(8).  As noted in its documentation, blktrace is a
       block layer IO tracing mechanism which provides detailed
       information about request queue operations up to user space.

       btt will take in binary dump data from blkparse, and analyse the
       events, producing a series of output from the analysis. It will
       also build .dat files containing "range data" -- showing things
       like Q activity (periods of time while Q events are being
       produced), C activity (likewise for command completions), and
       etc.

       Included with the distribution is a simple 3D plotting utility,
       bno_plot, which can plot the block numbers btt outputs if the -B
       option is specified. The display will display each IO generated,
       with the time (seconds) along the X-axis, the block number
       (start) along the Y-axis and the number of blocks transferred in
       the IO represented along the Z-axis.

OPTIONS         top

       -a
       --seek-absolute
           When specified on the command line, this directs btt to
           calculate seek distances based solely upon the ending block
           address of one IO, and the start of the next.  By default btt
           uses the concept of the closeness to either the beginning or
           end of the previous IO. See the Users Manual for more details
           about seek distances.

       -A
       --all-data
           Normally btt will not print out verbose information
           concerning per-process and per-device data.  If you desire
           that level of detail you can specify this option.

       -B <output name>
       --dump-blocknos=<output name>
           This option will output absolute block numbers to three files
           prefixed by the specified output name:

           prefix_device_r.dat
                  All read block numbers are output, first column is
                  time (seconds), second is the block number, and the
                  third column is the ending block number.

           prefix_device_w.dat
                  All write block numbers are output, first column is
                  time (seconds), second is the block number, and the
                  third column is the ending block number.

           prefix_device_c.dat
                  All block numbers (read and write) are output, first
                  column is time (seconds), second is the block number,
                  and the third column is the ending block number.

       -d <seconds>
       --range-delta=<seconds>
           btt outputs a file containing Q and C activity, the notion of
           active traces simply means that there are Q or C traces
           occurring within a certain period of each other. The default
           values is 0.1 seconds; with this option allowing one to
           change that granularity. The smaller the value, the more data
           points provided.

       -D <dev;...>
       --devices=<dev;...>
           Normally, btt will produce data for all devices detected in
           the traces parsed. With this option, one can reduce the
           analysis to one or more devices provided in the string passed
           to this option. The device identifiers are the major and
           minor number of each device, and each device identifier is
           separated by a colon (:). A valid specifier for devices 8,0
           and 8,8 would then be: 8,0:8,8.

       -e <exe,...>
       --exes=<exe,...>
           The -e option supplies the list of executables that will have
           I/Os analysed.

       -h
       --help
           Shows a short summary of possible command line option

       -i <input name>
       --input-file <input file>
           Specifies the input file to analyse.  This should be a trace
           file produced by blktrace (8).

       -I <output name>
       --iostat=<output name>
           The -I option directs btt to output iostat-like data to the
           specified file.  Refer to the iostat (sysstat) documentation
           for details on the data columns.

       -l <output name>
       --d2c-latencies=<output name>
           The -l option allows one to output per-IO D2C latencies
           respectively. The supplied argument provides the basis for
           the output name for each device.

       -L <freq>
       --periodic-latencies=<freq>
           The -L option allows one to output periodic latency
           information for both Q2C and D2C latencies. The frequency
           specified will regulate how often an average latency is
           output -- a floating point value expressing seconds.

       -m <output name>
       --seeks-per-second=<output name>
           Trigger btt to output seeks-per-second information. The first
           column will contain a time value (seconds), and the second
           column  will indicate the number of seeks per second at that
           point.

       -M <dev map>
       --dev-maps=<dev map>
           The -M option takes in a file generated by the provided
           script (gen_disk_info.py), and allows for better output of
           device names.

       -o <output name>
       --output-file=<output name>
           Specifies the output file name.

       -p <output name>
       --per-io-dump=<output name>
           The -p option will generate a file that contains a list of
           all IO "sequences" - showing the parts of each IO (Q, A, I/M,
           D, & C).

       -P <output name>
       --per-io-trees=<output name>
           The -P option will generate a file that contains a list of
           all IO "sequences" - showing only the Q, D & C operation
           times. The D & C time values are separated from the Q time
           values with a vertical bar.

       -q <output name>
       --q2c-latencies=<output name>
           The -q option allows one to output per-IO Q2C latencies
           respectively. The supplied argument provides the basis for
           the output name for each device.

       -Q <output name>
       --active-queue-depth=<output name>
           The -Q option allows one to output data files showing the
           time stamp and the depth of active commands (those issued but
           not completed).

       -r
       --no-remaps
           Ignore remap traces; older kernels did not implement the full
           remap PDU.

       -s <output name>
       --seeks=<output name>
           The -s option instructs btt to output seek data, the argument
           provided is the basis for file names output. There are two
           files per device, read seeks and write seeks.

       -S <interval>
       --iostat-interval=<interval>
           The -S option specifies the interval to use between data
           output, it defaults to once per second.

       -t <sec>
       --time-start=<sec>
       -T <sec>
       --time-end=<sec>
           The -t/-T options allow one to set a start and/or end time
           for analysing - analysing will only be done for traces after
           -t's argument and before -T's argument. (-t and -T are
           optional, so if you specify just -t, analysis will occur for
           all traces after the time specified. Similarly, if only -T is
           specified, analysis stops after -T's seconds.)

       -u <output name>
       --unplug-hist=<output name>
           This option instructs btt to generate a data file containing
           histogram information for unplug traces on a per device
           basis. It shows how many times an unplug was hit with a
           specified number of IOs released. There are 21 output values
           into the file, as follows:

               a value of 0 represents 0..4 counts
               a value of 1 represents 5..9 counts
               a value of 2 represents 10..14 counts
               etc, until
               a value of 20 represents 100+ counts

           The file name(s) generated use the text string passed as an
           argument for the prefix, followed by the device identifier in
           major,minor form, with a .dat extension.  For example, with
           -u up_hist specified on the command line:
           up_hist_008,032.dat.

       -V
       --version
           Shows the version of btt.

       -v
       --verbose
           Requests a more verbose output.

       -X
       --easy-parse-avgs
           Provide data in an easy-to-parse form and write it to a file
           with .avg exentsion

       -z <output name>
       --q2d-latencies=<output name>
           The -z option allows one to output per-IO Q2D latencies
           respectively. The supplied argument provides the basis for
           the output name for each device.

       -Z
       --do-active
           The -Z will output files containing data which can be plotted
           showing per-device (and total system) I/O activity.

AUTHORS         top

       btt was written by Alan D. Brunelle.  This man page was created
       from the blktrace documentation by Bas Zoetekouw.

REPORTING BUGS         top

       Report bugs to <linux-btrace@vger.kernel.org>

COPYRIGHT         top

       Copyright © 2006 Jens Axboe, Alan D. Brunelle and Nathan Scott.
       This is free software.  You may redistribute copies of it under
       the terms of the GNU General Public License
       <http://www.gnu.org/licenses/gpl.html>.  There is NO WARRANTY, to
       the extent permitted by law.
       This manual page was created for Debian by Bas Zoetekouw.  It was
       derived from the documentation provided by the authors and it may
       be used, distributed and modified under the terms of the GNU
       General Public License, version 2.
       On Debian systems, the text of the GNU General Public License can
       be found in /usr/share/common-licenses/GPL-2.

SEE ALSO         top

       The btt Users Guide, which can be found in
       /usr/share/doc/blktrace/btt.pdf
       bno_plot(1), blktrace(8), blkparse(1), verify_blkparse(1),
       blkrawverify(1), btt(1)

COLOPHON         top

       This page is part of the blktrace (Linux block layer I/O tracer)
       project.  Information about the project can be found at [unknown
       -- if you know, please contact man-pages@man7.org] It is not
       known how to report bugs for this man page; if you know, please
       send a mail to man-pages@man7.org.  This page was obtained from
       the project's upstream Git repository
       ⟨http://git.kernel.org/cgit/linux/kernel/git/axboe/blktrace.git/⟩
       on 2021-08-27.  (At that time, the date of the most recent commit
       that was found in the repository was 2021-06-28.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

blktrace git-20070910192508September 29, 2007                     BTT(1)

Pages that refer to this page: blkparse(1)blkrawverify(1)bno_plot(1)btt(1)verify_blkparse(1)blkiomon(8)blktrace(8)btrace(8)