Examples

Here is a collection of examples written using GWR.

Abstract Examples

Flaky Component

This shows a minimal runnable simulation with custom component behavior.

How to run it:

cargo run --bin flaky-component -- --seed 1 --drop 0.5 --num-packets 1000

Try varying --drop and comparing the number of packets received.

Flaky with Delay

This shows a component using explicit time delays, buffering, and custom functionality.

As with all the examples, you can determine the command-line arguments by running with --help:

cargo run --bin flaky-with-delay -- --help

Try varying the delay as well as the drop rate.

Scrambler

The scrambler shows how component can have dynamic port connections at runtime depending on command-line arguments.

Compare running:

cargo run --bin scrambler

against

cargo run --bin scrambler -- -s

System Exploration Examples

These examples show GWR being used to build larger systems that you might find in silicon devices.

Sim Pipe

This simulation shows how you can model a credit-controlled pipeline in order to understand throughput, buffering, latency, and backpressure.

Try running it and varying the data and credit delays and the size of the data buffer which controls the number of credits that can be issued:

cargo run --bin sim-pipe -- --stdout --pipe-data-delay 10 --pipe-buffer-entries 10 --pipe-credit-delay 10

If you now vary the size of the pipe buffer or the delays you will see the impact on pipeline throughput.

Sim Ring

The ring-based interconnect simulation shows how the arbitration can cause such an architecture to deadlock.

The Terminus recipe can be used when you want to sweep ring size, arbitration priority, buffer sizes, or trace settings without rebuilding a long command by hand.

cargo run --bin terminus -- run --recipe examples/sim-ring/recipes/explore_ring_priorities.yaml

You will notice how having a fair priority for ring traffic causes deadlock and it is essential to give priority to traffic in the ring to prevent this.

Sim Fabric

This simulation demonstrates how GWR can be used to build models at different levels of abstraction.

You can use the Terminus recipes to explore the impact of the level of abstraction modelled, which you will see produce quite different performance numbers:

cargo run --bin terminus -- run --recipe examples/sim-fabric/recipes/explore_model.yaml

You can show that with a different traffic pattern the two models do produce very similar results by running the above command again and adding:

--ARGS "--traffic-pattern all-to-one"

There is also a recipe to show how to explore the impact of the fabric data ticks per hop:

cargo run --bin terminus -- run --recipe examples/sim-fabric/recipes/explore_ticks_per_hop.yaml