Reframes the proposed GQA FlashAttention design onto kernbench's actual
execution model (greenlet tl API + IPCQ), replacing the composite-centric
mechanism that does not match the simulator:
- Records relationship to existing baseline kernels (_attention_mesh_kv/mlo,
milestone-gqa-llama70b) and their 3 deliberate limitations.
- Mechanism is greenlet tl (per-op latency; no fusion benefit), not
composites; running (m,l,O) is Python handles; reduction is tl.send/recv.
- Tree reduction (log N) replaces baseline all-to-all fan-out (N-1).
- Pseudocode rewritten in real tl.* signatures; depends on ADR-0061/62/63.
- Rejects composite-IPCQ-push + composite-carried-state + flash-composite
with documented efficient alternatives.
- Adds verification plan.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Proposed prerequisites surfaced while evaluating the GQA fused-attention
ADR against the actual kernbench tl/sim_engine implementation:
- ADR-0061 tl.broadcast: data-faithful GQA head reuse (fixes the
MemoryStore nbytes check that forces h_q==h_kv==1 today).
- ADR-0062 tl.load_async: non-blocking HBM tile load for KV prefetch
(KV-load-bound decode/long-context overlap).
- ADR-0063 tl.scratch_scope: per-tile scratch recycling (removes the
1 MiB bump-allocator ceiling that caps context at S=16).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
ywkang
Yangwook Kang