Petal: The Calyx Profiler

Note: Petal is still in development. If you have any suggestions, thoughts, or feedback, please let us know!

Profilers can help you analyze performance information to find places you can optimize in your code. Currently, the Calyx profiler prouduces timing information in terms of cycle counts.

Setup

In order to run Petal, you need:

• fud2
• Petal and other internal tools within the Calyx repository; run cargo build --all to build all of them.
• The Python vcdvcd library. Running fud2 env init should install this for you.
• A clone of Brendan Gregg’s Flamegraph repository: https://github.com/brendangregg/FlameGraph

Then, you need to edit your fud2 configuration file to specify the location of flamegraph.pl within the Flamegraph repository:

ex)

[flamegraph]
script = "/home/ayaka/projects/FlameGraph/flamegraph.pl"

Basic Use

To obtain a flame graph from a Calyx file, run fud2 with an SVG output file and the --through petal option:

ex)

fud2 tests/correctness/pow.futil -o pow.svg --through petal -s sim.data=tests/correctness/pow.futil.data

The produced flame graph is “flattened”, which means that each parallel arm gets its own “cycle”. So, if arm A and arm B were executing on a single cycle, the flame graph would account for a cycle in arm A and a cycle in arm B. You can view and interact with the flame graph using your favorite web browser.

If you retain the fud2 build directory with the --keep option or the --dir option, you will find additional profiler output files in <FUD2_BUILD_DIRECTORY>/profiler-out:

• scaled-flame.svg: A scaled flame graph, where a cycle is divided between the parallel arms in execution. So, if arm A and arm B were executing on a single cycle, the flame graph would account for 0.5 cycles in arm A and 0.5 cycles in arm B.
• timeline_trace.pftrace: A file in Perfetto’s native protobuf trace format. Inputting this file into Perfetto UI will visualize a timeline of your Calyx program’s simulation.
• cell-stats.csv: A table quantifying the duration of each cell activation and classification of cycles within it.
• group-stats.csv: A table showing the number of cycles and the number of times for which a group was active, along with the minimum, maximum, and average duration of the group across calls.

Running Petal for ADL programs

Currently, the profiler supports programs written in Dahlia and Calyx-Py.

Dahlia Profiling

Dahlia programs can be profiled by using the petal-dahlia op instead of the petal op.

ex)

fud2 examples/dahlia/dot-product.fuse -o svgs/dot-product.svg --through petal-dahlia -s sim.data=examples/dahlia/dot-product.fuse.data

Note: The svg file outputted is the flattened flame graph at the Calyx level, so we highly recommend retaining the fud2 build directory.

If you retain the fud2 build directory with the --keep option or the --dir option, you will find additional Dahlia profiler output files in <FUD2_BUILD_DIRECTORY>/profiler-out (on top of the Calyx profiler output files listed in Basic Use):

• dahlia-flat-flame.svg: A flattened flame graph at the Dahlia level.
• dahlia-scaled-flame.svg: A scaled flame graph at the Dahlia level.
• dahlia_timeline_trace.pftrace: A timeline view file at the Dahlia level in Perfetto’s native protobuf trace format. Inputting this file into Perfetto UI will visualize a timeline of your Dahlia program’s simulation.

Calyx-py Profiling

Calyx-py programs can be profiled by using the petal-calyx-py op. If the program has an argument, you can provide the arguments into the profiler simulation run via the profiler.py-args argument.

ex)

fud2 frontends/queues/tests/strict/strict_6flow_test.py -o svgs/strict_6flow_test.svg --through petal-calyx-py -s sim.data=frontends/queues/tests/strict/strict_6flow_test.data -s profiler.py-args="20000 --keepgoing"

Note: The svg file outputted is the flattened flame graph at the Calyx level, so we highly recommend retaining the fud2 build directory.

If you retain the fud2 build directory with the --keep option or the --dir option, you will find additional Calyx-py profiler output files in <FUD2_BUILD_DIRECTORY>/profiler-out (on top of the Calyx profiler output files listed in Basic Use):

• mixed-flat-flame.svg: A flattened flame graph that shows both Calyx-py names and Calyx names.
• mixed-scaled-flame.svg: A scaled flame graph that shows both Calyx-py names and Calyx names.
• py-flat-flame.svg: A flattened flame graph at the Calyx-py level.
• py-scaled-flame.svg: A scaled flame graph at the Calyx-py level.

Running the Prototype

A prototype of Petal can also be run using fud2 with the same setup. Simply replace the fud2 op (--through <OP>) as follows:

• Calyx profiling: petal –> profiler
• Dahlia profiling: petal-dahlia –> dahlia-profiler
• Calyx-Py profiling: petal-calyx-py –> calyx-py-profiler

NOTE: The prototype can be >= 10x slower than the current implementation.