iowatcher man page

iowatcher — Create visualizations from blktrace results


iowatcher [options] [--] [program arguments ...]


iowatcher graphs the results of a blktrace run.  It can graph the result of an existing blktrace, start a new blktrace, or start a new blktrace and a benchmark run.  It can then create an image or movie of the IO from a given trace.  iowatcher can produce either SVG files or movies in mp4 format (with ffmpeg) or ogg format (with png2theora).



Print a brief usage summary.

-d, --device device

Controls which device you are tracing.  You can only trace one device at a time for now.  It is sent directly to blktrace, and only needed when you are making a new trace.

-D, --blktrace-destination destination

Destination for blktrace.

-p, --prog

Run a program while blktrace is run. The program and its arguments must be specified after all other options.  Note that this option previously required the program to be given as a single argument but it now tells iowatcher to expect extra arguments which it should be run during the trace.


End option parsing. If --prog is specified, everything after -- is the program to be run. This can be useful if the program name could otherwise be mistaken for an option.

-K, --keep-movie-svgs

Keep the SVG files generated for movie mode.

-t, --trace path

Specify the name of the file or directory in which blktrace output is located. iowatcher uses a dump from blkparse, so this option tries to guess the name of the corresponding per-CPU blktrace data files if the dump file doesn't already exist.  To add multiple traces to a given graph, you can specify --trace more than once.  If path is a directory, iowatcher will use the name of the directory as the base name of the dump file and all trace files found inside the directory will be processed.

-l, --label label

Sets a label in the graph for a trace file.  The labels are added in the same order as the trace files.

-m, --movie [style]

Create a movie.  The file format depends on the extension used in the -o file option.  If you specify an .ogv or .ogg extension, the result will be Ogg Theora video, if png2theora is available.  If you use an .mp4 extension, the result will be an mp4 video if ffmpeg is available.  You can use any other extension, but the end result will be an mp4.  The accepted style values are spindle for a circular disc-like effect (default) or rect for a rectangular graph style.

-T, --title title

Set a title to be placed at the top of the graph.

-o, --output file

Output filename for the SVG image or video. The video format used will depend on the file name extension. See --movie for details.

-r, --rolling seconds

Control the duration for the rolling average.  iowatcher tries to smooth out bumpy graphs by averaging the current second with seconds from the past.  Larger numbers here give you flatter graphs.

-h, --height height

Set the height of each graph

-w, --width width

Set the width of each graph

-c, --columns columns

Number of columns in graph output

-x, --xzoom min:max

Limit processed time range to min:max.

-y, --yzoom min:max

Limit processed sectors to min:max.

-a, --io-plot-action action

Plot action (one of Q, D, or C) in the IO graph.

-P, --per-process-io

Distinguish between processes in the IO graph.

-O, --only-graph graph

Add a single graph to the output (see section Graphs for options).  By default all graphs are included. Use -O to generate only the required graphs.  -O may be used more than once.

-N, --no-graph type

Remove a single graph from the output (see section Graphs for options). This option may be used more than once.


Values accepted by the -O and -N options are:

  io, tput, latency, queue_depth, iops, cpu-sys, cpu-io, cpu-irq, cpu-user, cpu-soft


Generate graph from the existing trace.dump:

# iowatcher -t trace

Skip the IO graph:

# iowatcher -t trace.dump -o trace.svg -N io

Only graph tput and latency:

# iowatcher -t trace.dump -o trace.svg -O tput -O latency

Generate a graph from two runs, and label them:

# iowatcher -t ext4.dump -t xfs.dump -l Ext4 -l XFS -o trace.svg

Run a fio benchmark and store the trace in trace.dump, add a title to the top, use /dev/sda for blktrace:

# iowatcher -d /dev/sda -t trace.dump -T 'Fio Benchmark' -p fio some_job_file

Make a movie from an existing trace:

# iowatcher -t trace --movie -o trace.mp4


iowatcher was created and is maintained by Chris Mason.

This man page was largely written by Andrew Price based on Chris's original README.

See Also

blktrace(8), blkparse(1), fio(1), mpstat(1)


April 2014 iowatcher User Commands