What's in source/

Source code overview

The source/ folder of this repo is a mirror of the team's HPC MiniWeather Project. Below is what every directory contains and how it maps to the visualization you see on the home page.

The 7-point stencil, four ways

All four implementations compute the same kernel — a 3D 7-point Laplacian-style stencil over a (nx × ny × nz) grid. They differ in how the work is scheduled across hardware:

• src/stencil_cpu_serial.cpp — single thread, plain triple loop. Reference correctness; everything else is benchmarked against this.
• src/stencil_cpu_blocked.cpp — same math, but the loops are tiled into blocks sized to fit in L1/L2. Same FLOPs, far fewer cache misses.
• src/stencil_cpu_parallel.cpp + src/halo.cpp — OpenMP threads over the inner loops; when MPI is enabled, multiple ranks each own a sub-block of the grid and exchange halo (ghost) cells every step.
• src/stencil_gpu.cu + src/stencil_gpu.cpp — same kernel as a CUDA grid. Each cell is one thread; tiled into shared memory for coalesced loads.

Other folders

• include/ — public headers (stencil.hpp, halo.hpp, config.hpp, …).
• slurm/, submit.sbatch, submit_*.slurm — SLURM batch scripts for the Magic Castle cluster runs (serial, parallel, scaling sweep, GPU).
• scripts/ — Python helpers: visualize_weather.py renders the PNG/GIF artefacts you see in the "Cluster outputs" section; plot_results.py + collect_results.py build the speedup/scaling tables.
• results/ — the artefacts themselves (also mirrored into web/assets/ so this Pages site can display them).
• docs/ — the team's writeup: ARCHITECTURE.md, RESULTS.md, SYSTEM.md, the EuroHPC proposal, the pitch slides, and a reproduction guide.
• tests/ — sanity check at 16³ and a Python verifier that compares all four backends against each other to flag correctness regressions.
• profiling/ — instrumentation notes for the cluster runs.
• CMakeLists.txt, run.sh — build / configure / run from a single entry point. ./run.sh build compiles with whatever toolchain modules the cluster has loaded; ./run.sh test launches a smoke run.

How the in-browser sim maps to this

The interactive page runs a 2D analogue of the same operator. Same stencil shape (centre + face-neighbours), same diffusion math, same buoyancy term — just one dimension fewer so the result fits on a canvas. Resolution, diffusion and buoyancy are sliders so you can feel what the cluster code is computing per cell, per step, before it's distributed across thousands of threads.