End-to-end wires C=8 P=8 d_head=128 prefill with snake-ring inter-CUBE
SFR, intra-CUBE PE-SP (all 64 ranks active), and the milestone bench
panel. Decode kernel gains lrab-adapted center-root reduce for the
2×4 sub-mesh per ADR-0060 §4.2.
Increment 1 — SFR multi-row snake
src/kernbench/ccl/sfr_config.py: configure_sfr_intercube_ring gains
submesh_shape / submesh_origin kwargs; installs a Hamiltonian snake
ring through a rectangular sub-mesh (every hop is 1-hop physical
neighbour). Backward-compat: 1D-row behaviour preserved when
submesh_shape is None.
tests/test_intercube_snake_ring.py (12 tests)
Increment 2 — Decode lrab-adapted center-root reduce
src/kernbench/benches/_gqa_attention_decode_long.py: new sub_w param
(default 0 = existing 1D-chain). sub_w >= 2 selects the ADR-0060
§4.2 prescribed lrab-adapted Phase 1+2 reduce (bidirectional row +
bidirectional col converge to the center cube), with log-sum-exp
_merge_running replacing the plain + of lrab.
tests/attention/test_gqa_decode_long_2d_reduce.py (4 tests)
Increment 3 — Prefill kernel at C=8 (no production change)
Verified by inspection that the existing prefill_long kernel +
Increment 1's snake SFR already work at C=8 without any kernel
edit. The kernel speaks logical W/E; the snake routes it.
tests/attention/test_gqa_prefill_long_c8_snake.py (3 tests)
Increment 4 — Intra-CUBE PE-SP in prefill (all 64 ranks)
src/kernbench/benches/_gqa_attention_prefill_long.py: new P param
(default 1 = existing PE-0-only). P > 1 splits T_q query-axis-wise
across the P PEs of each CUBE; output rows are disjoint per PE so
no intra-CUBE reduce is needed; each PE drives its own same-lane
ring (P parallel rings).
tests/attention/test_gqa_prefill_long_pe_sp.py (5 tests)
Increment 5 — LLaMA-scale milestone bench panel
src/kernbench/benches/milestone_gqa_headline.py: new panel
single_kv_group_prefill_gqa_c8_p8 (C=8, P=8, T_q=S_kv=32K,
d_head=128). _run_prefill_panel extended with P/T_q/d_head
defaults; routes snake SFR when C > mesh_w.
tests/attention/test_milestone_gqa_single_kv_group_prefill_panel.py (3 tests)
Total: 4 production files modified, 5 new test files, 27 new tests.
Followed the Phase 1/2 protocol per CLAUDE.md throughout.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Comment-only change. Adds a kernbench-only limitation note at the
Tile-0 / bootstrap block in all four GQA attention kernels:
- persistent (m, l, O) must live outside tl.scratch_scope so
subsequent tiles' merges can read them;
- kernbench has no scratch-backed initializer (tl.zeros / tl.full
return addr=0 handles), so we can't seed (-inf, 0, 0) and rely
on tl.copy_to;
- therefore Tile 0 must compute the initial running state directly.
prefill_long adds a third bullet noting the ring-step ordering reason
(k=0 must send W before any k>0 can recv E, so the (t=0, k=0) step has
to run outside the scoped loop where the send is conditional on C > 1).
Each block also notes that a real Triton port collapses Tile 0 into a
unified loop (SSA tensors stay live across iterations).
No behavior change; tests unchanged.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Three logically distinct changes, bundled for atomic test green:
1. **P3c — prefill_long tile-granular Ring KV** (ADR-0060 §5.5.1 amendment).
Convert the ring from slice-granular (one full ``(d_head, S_local)``
KV slice per step) to tile-granular (``n_tiles`` tiles of
``TILE_S_KV`` per step). Nested loop with outer tile, inner ring step:
each tile propagates through all C ring positions before the next
tile starts, so IPCQ in-flight depth stays at 1 per direction.
Bootstrap at ``(t=0, k=0)`` outside the scratch_scope establishes the
persistent ``(m, ℓ, O)``; every other iteration scope-wraps + persists
via ``copy_to``. Per-rank persistent scratch shrinks to ~1 KB; per-tile
scope bounded by TILE_S_KV regardless of S_local. Headline:
prefill_long now completes at S_kv=128K (previously overflowed).
New: ``tests/attention/test_gqa_prefill_long_tile_ring.py``
(3 tests — ceiling-lift + tile-granular ipcq_copy count +
per-CUBE distributed output regression guard).
2. **Rename ``gqa_*`` → ``gqa_attention_*``** across kernel files,
function names, and importers. The "attention" name makes the role
explicit (GQA is grouped-query attention) and matches upstream Triton
FlashAttention naming conventions. Renames:
_gqa_decode_long.py -> _gqa_attention_decode_long.py
_gqa_decode_short.py -> _gqa_attention_decode_short.py
_gqa_prefill_long.py -> _gqa_attention_prefill_long.py
_gqa_prefill_short.py -> _gqa_attention_prefill_short.py
And function names ``gqa_<phase>_<context>_kernel`` →
``gqa_attention_<phase>_<context>_kernel``. Updated 1 bench file
(milestone_gqa_headline.py) and 10 test files.
3. **ADR-0060 / 0062 / 0063 / 0064: Proposed → Accepted**.
All four are reflected in production code and covered by tests:
- ADR-0060 (GQA fused attention): 4 kernels deployed; §5.5.1
amendment added for the tile-granular Ring KV introduced by P3c
(EN + KO mirror).
- ADR-0062 (lazy tl.load): LoadFuture + _await_pending live in
tl_context.py.
- ADR-0063 (tl.scratch_scope + tl.copy_to): used in every chain
reduce + tile sweep + ring step. EN-only previously; KO
translation authored as part of this commit (CLAUDE.md
bidirectional rule).
- ADR-0064 (per-op-type CPU issue cost): cpu_issue_cost.py +
issue_cost_table wiring in tl_context.py (Phase E).
Files git mv'd from docs/adr-proposed/ to docs/adr/ (EN) and
docs/adr-ko/ (KO). ADR-0061 (tl.broadcast) stays Proposed — no
implementation; documented as optional convenience primitive in
the ADR itself.
Tests: 88/88 focused regression green
(tests/attention/ + Phase E + TL discipline).
ADR pair verification: ``python tools/verify_adr_lang_pairs.py`` OK.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
mukesh