Bare-Metal Provisioning and Determinism
How Kronos pins microarchitecture, libraries, and topology on owned nodes so that physics runs are numerically stable across years.
Determinism as a provisioning requirement
For the reproducible core of L0, provisioning is not just about acquiring cycles; it is about acquiring the same cycles every time. A coupled solve of the breeder equilibrium and blanket thermomechanics can be chaotic in the mathematical sense: tiny numerical differences amplify. To certify a result years apart, Kronos pins the entire numerical environment on bare-metal.
- Fixed CPU microarchitecture and vector ISA per reproducibility class
- Pinned BLAS, LAPACK, MPI, and PETSc versions
- Disabled frequency scaling and turbo variability on certified nodes
- Locked NUMA topology and thread affinity
- Recorded firmware and microcode revisions
The reproducibility class
Certified nodes are grouped into reproducibility classes. A run declares its class; the scheduler places it only on matching hardware. This means a Grad-Shafranov equilibrium computed for the negative-triangularity delta -0.30 breeder shape can be re-derived bit-for-bit, which matters because these equilibria seed the twin surrogates that will later run in real time.
Why this precedes hardware
The breeder does not exist yet; construction begins Q2 2027 and first tritium is expected around 2030. Until then, the numerical model is the machine. If the model is not reproducible, there is nothing stable to design against. Bare-metal determinism is therefore a design-integrity requirement, not an optimization.
Provisioning also records everything needed to reconstruct a run: node identity, environment hash, library manifest, and RNG seeds. This manifest travels with every result into the petabyte archive, so a burner or breeder study can be audited and replayed on demand. Determinism without recording is not reproducibility; the two are provisioned together.