Seekwatcher generates graphs from blktrace runs to help visualize IO patterns and performance. It can plot multiple blktrace runs together, making it easy to compare the differences between different benchmark runs.
Ext3 vs XFS creating 20 copies of the Linux kernel sources
Seekwatcher uses matplotlib to generate graphs, and most distros have a package for this. You'll also need to install python and the numpy module. It is common for the matplotlib packages to depend on numpy, so installing a distro's matplotlib should get you what you need.
seekwatcher --movie uses mencoder to create mpg files, but it also leaves around all the .pngs so you can use your own favorite program.
Once those are setup, just copy the seekwatcher script to a bin directory and make it executable.
There are three basic ways to run seekwatcher. It can either generate graphs from an existing blktrace run, start blktrace and run a program for you, or make a series of pngs from a single trace. If seekwatcher starts and stops blktrace, the trace runs are kept so they can be graphed again later.
Examples:
This will start blktrace on /dev/sda6, run find / > /dev/null, save the blktrace output to find.trace and save the graph to find.png.
seekwatcher -t find.trace -o find.png -p 'find / > /dev/null' -d /dev/sda6
To regenerate the graph from the saved trace file:
seekwatcher -t find.trace -o find.png
To compare multiple traces, use the -t flag multiple times. Providing a corresponding -l flag for each trace will create labels on the graphs.
seekwatcher -t ext3.trace -t xfs.trace -l ext3 -l xfs -o ext3_vs_xfs.png
Finally, you can also make a series of images (and mpg) of the IO generated by a given run. For these images, a disk is simulated as a grid of x,y coordinates and every sector read/written is plotted with a black square. Squares fade as the IO ages, blanking out after 10 frames.
To create an animation from ext3.trace and store the resulting png files in some_dir/ext3-00000N.png (N is replaced by the frame number). mencoder is run to create some_dir/ext3.mpg based on the images:
seekwatcher -t ext3.trace -o some_dir/ext3.png --movie
Seekwatcher creates 3 graphs by default: a plot of each sector read or written, the number of seeks per second, and the throughput per second during the run. Sometimes the plot of each sector can be difficult to read, especially when comparing two runs with very different IO patterns. seekwatcher --no-io-graph will disable this plot. Another option is to use seekwatcher --zoom start:end to specify the range on the yaxis you want included in the graph. The range is specified in MB, and using a range of 0:0 will turn off seekwatcher's attempt at autoscaling the plot.
seekwatcher -t ext3.trace -z 10000:20000 -o ext3.png seekwatcher -t ext3.trace -z 0:0 -o ext3-no-zoom.png
You can change the plot type used in the IO graph with --io-graph-dots. Matplotlib gives a long list of choices. You might try '-' (solid line) or ',' (pixels):
seekwatcher -t ext3.trace --io-graph-dots=,
Seekwatcher uses a rolling average of the seek counts and throughput values to make graphs smoother. You can control the number of seconds rolled together (by default total trace time / 25) with seekwatcher --rolling-avg
By default, seekwatcher saves the graph into a file called trace.png. seekwatcher -o filename can be used to save it to a different file. The extension specified controls what type of file is created, choices include .png, .jpg, .eps, and .svg. The resolution used can be controlled with --dpi num. By default, seekwatcher uses a 8x6 pagesize and a dpi of 120.
