-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.
