Files
kernbench2/docs/adr/ADR-0003-dev-target-system-hierarchy.md
ywkang 687c98086d ADR housekeeping: category prefixes, lifecycle folders, retroactive 0034-0037
Filename + lifecycle:
- ADR rename to ADR-NNNN-<cat>-title.md with 8 3-letter category prefixes
  (dev / mem / lat / prog / algo / par / api / ver). Numbers stay immutable.
- ADR Lifecycle split into 3 folders, documented in CLAUDE.md Part 2:
  docs/adr/ (Accepted), docs/adr-proposed/ (Proposed/Stub/Draft),
  docs/adr-history/ (Superseded/Merged). Status field gains "Draft" for
  retroactive docs pending verification.

Merges (one ADR per topic, no change-history annotations):
- ADR-0017 absorbs ADR-0019 (Cube NOC + per-PE HBM connectivity, 10 D-items)
- ADR-0014 absorbs ADR-0021 (PE pipeline execution model, 8 D-items incl.
  TileToken self-routing and multi-op composite epilogue scope)
- ADR-0023 absorbs docs/ipcq-dma-codesign-hw.md as new "HW Realization
  Notes (Informative)" section (D16-D23 + Open HW Questions). codesign-hw.md
  deleted; ADR-0019/0021 moved to adr-history with one-line stub status

Retroactive documentation (G4 closures, code-verified):
- ADR-0037 forwarding component (TransitComponent: first-flit overhead,
  serial worker, path-based routing, single impl/multiple names)
- ADR-0036 IO_CPU component (target_start_ns global barrier stamping,
  per-cube fan-out, response aggregation)
- ADR-0035 M_CPU & M_CPU.DMA component (3 fan-out paths, DMA Resources,
  target_start_ns passthrough)
- ADR-0034 HBM controller internal design (per-PC state, address-based
  selection, flit-aware per-flit commit, async finalize, command-only
  fallback path)

Content updates:
- ADR-0010 expanded to full CLI surface (run/probe/web), retitled
  "Command Line Interface and Execution Semantics"
- ADR-0007 D2 rewritten to current state; ADR-0015 supersession notes pruned
- ADR-0005 wrapped in Decision header with D1-D5; ADR-0022 metadata
  block replaced with standard Status header
- ADR-0024 trimmed to rank=SIP launcher essentials (D1-D4);
  ADR-0027 cleaned of supersession history
- ADR-0033 D6 cleanup: address-based PC selection moved out of future-work
  (now documented in ADR-0034 D3); related D1/D3 wording realigned
- Cross-references back-filled in 5 ADRs (G3 gaps closed)

Onboarding docs split:
- docs/onboarding/ created
- moved: hw-architecture-overview.md, latency-model.md, di-presentation.md,
  ccl-author-guide{,.en}.md
- references updated in README, ADR-0023{,.en}, src/kernbench/ccl/__init__.py

Source / test / yaml: ADR-NNNN cross-references in docstrings and YAML
comments updated after the merges (ADR-0021->0014 D6, ADR-0019->0017 D8).
No behavior change.

Tooling:
- tools/verify_adr_lang_pairs.py + tests/test_verify_adr_lang_pairs.py
  (ADR EN/KO pair invariant checker)
- .claude/commands/report.md tracked (/report slash command)
- .gitignore: allow .claude/commands/*.md while keeping settings files ignored

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-20 01:15:55 -07:00

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ADR-0003: Target System Hierarchy & Modeling Scope

Status

Accepted

Context

We need a system-level simulator to evaluate LLM kernel performance on our AI Accelerator platform. The platform is organized as a compute tray containing multiple identical SIPs connected via PCIe or UAL through switching fabrics, with a host CPU issuing commands/kernels.

Decision

We model the system hierarchy explicitly:

D1. Tray-level

  • A compute tray contains:
    • Host CPU (issues requests / coordinates runtime & data placement)
    • Multiple identical SIPs (accelerators)
    • Interconnect fabric between SIPs (PCIe and/or UAL via switches)

D2. SIP-level

  • A SIP is a multi-die package composed of:
    • Multiple CUBEs (HBM die + compute PEs + UCIe)
    • One or more IO chiplets (host/SIP interfaces)
  • IO chiplets:
    • provide interfaces: PCIe-EP, IO_CPU, optionally UAL-EP
    • can be multiple per SIP
    • placement constrained to SIP shoreline (top/bottom/left/right); each shoreline may host 12 IO chiplets

D3. CUBE-level

  • A CUBE contains:
    • HBM + memory controller (HBM_CTRL)
    • NOC (on-die fabric): carries all intra-cube traffic including HBM data, inter-cube (UCIe), command (M_CPU↔PE_CPU), and shared SRAM access. Must provide: full-BW PE↔local HBM path, PE↔SRAM connectivity, PE↔UCIe connectivity, M_CPU↔PE command path. NOC topology is an implementation choice (e.g., 2D mesh, ring, crossbar); current implementation uses a 2D mesh with XY routing (see ADR-0017). HBM_CTRL is attached to each PE's local NOC port (local HBM = minimal hop).
    • Shared SRAM: cube-level shared memory accessible by all PEs via NOC
    • management/control CPU (M_CPU) coordinating PE command distribution and completion aggregation
    • multiple PEs
    • up to 4 UCIe endpoints (N/E/W/S) for CUBE↔CUBE and CUBE↔IO connectivity

D4. PE-level

  • A PE can execute one kernel instance
  • PE contains internal control + accelerators (modeled at PE view granularity):
    • PE_CPU, command handler, PE_TCM, DMA/GEMM/MATH engines, internal queues

Consequences

  • The simulator supports abstraction by “views”:
    • SIP view hides PE internals
    • CUBE view treats each PE as a single block
    • PE view expands PE internals
  • Topology remains parameterized; sizes/counts/links come from configuration.
  • SPEC R3/R5
  • ADR-0005 (diagram views)
  • ADR-0017 (cube NOC 2D mesh architecture)