Fault Simulation

PPSFP (Parallel-Pattern Single-Fault Propagation) style fault simulators and other utility functions for use in various projects. These fault simulators are meant to be correct (ensured by unit-tests) and reasonably fast.

Fault simulation has $O(n^3)$ complexity. Every fault is simulated with every pattern involving every combinational gate in the circuit. We measure performance in terms of gates * faults * patterns / second. How fast can we make it?

Quick Start

This project has submodules. To ensure everything is up-to-date, run

git submodule update --init --recursive

after git clone, git pull or git checkout.

This project manages reproducible programming environments with:

• uv for managing python environments.
• nix for managing non-python tools and benchmark designs. Follow this guide or this guide to setup nix-eda binary cache to avoid re-building EDA-related tools.

Run all unit-tests: uv run pytest

Run a naive, baseline fault simulation with 1024 random patterns: uv run main.py tests/c6288.bench

Same on an 18k-gate circuit: uv run main.py polito-itc99-b15-sky130

nix develop makes quaigh available, another simulator/atpg written in rust.

To run Jupyter Notebooks in the reproducible programming environment, install a kernelspec:

uv run ipython kernel install --user --env VIRTUAL_ENV $(pwd)/.venv --env PATH ${PATH} --name=uv-env

Run a Jupyter Lab server locally:

uv run jupyter lab

Choose uv-env as kernel in Jupyter Lab.

Performance Statistics

Numbers are given in gfs/s = gates * faults * patterns / second.

Single-core SAFSimSimple on 1024 patterns (baseline):

OS, CPU, RAM	tests/c6288.bench	polito-itc99-b15-sky130
MacOS, M3 Max, 32GiB (Stefan)	1.52G	1.97G
WSL, i7-14650HX, 15GiB (Zhang)	1.68G	2.03G
Ubuntu, Xeon E5-1650, 251GiB (Nosaka)	0.94G	1.18G
WSL2, ?, ? (Kawachi)	0.82G	?
GH Codespace, EPYC 7763 (Kelvin)	1.03G	?
Ubuntu, i5-8265U, 8GiB (Kelvin)	0.77G	?

Notes

Common Fault Classes:
DT - Detected
DS - Detected By Simulation
DI - Detected By Implication
PT - Possibly detected
UD - Undetectable
UB - Undetectable - blocked
UR - Undetectable - redundant
AU - ATPG untestable
AN - ATPG untestable - not detected
ND - Not detected
NO - Not detected - not observed