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gqa(decode-4cases): rename bench/kernels/panels with long_ctx token

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The 4-cases comparative study is specifically about long-context
decode (LLaMA-3.1-70B, S_kv=128K, T_q=1); the long_ctx token in the
names makes the scope explicit and aligns with the existing
_gqa_attention_decode_long convention.

Renames (mechanical; no semantic change):
  - bench file:   milestone_gqa_decode_4cases.py
                  → milestone_gqa_decode_long_ctx_4cases.py
  - bench name:   milestone-gqa-decode-4cases
                  → milestone-gqa-decode-long-ctx-4cases
  - output dir:   1H_milestone_output/gqa_decode_4cases/
                  → 1H_milestone_output/gqa_decode_long_ctx_4cases/
  - env vars:     GQA_DECODE_4CASES_RUN / _TOPOLOGY
                  → GQA_DECODE_LONG_CTX_4CASES_RUN / _TOPOLOGY
  - 4 kernel files _gqa_attention_decode_<case>.py
                  → _gqa_attention_decode_long_ctx_<case>.py
  - 4 kernel functions gqa_attention_decode_<case>_kernel
                  → gqa_attention_decode_long_ctx_<case>_kernel
  - 4 dispatch kinds  decode_<case> → decode_long_ctx_<case>
  - 4 panel names     single_kv_group_decode_gqa_<case>
                      → single_kv_group_decode_long_ctx_gqa_<case>
  - 4 helper functions _run_decode_panel_<case>
                       → _run_decode_panel_long_ctx_<case>
  - test file renamed in lockstep

Also: Case 4 smoke test now uses its case-specific helper
_run_decode_panel_long_ctx_cube_sp_pe_sp (consistent with Cases 1-3)
instead of the legacy _run_decode_panel from milestone_gqa_headline.
16 tests pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
Mukesh Garg
2026-06-15 16:09:21 -07:00
parent 3c155be8e6
commit ddee28a499
6 changed files with 123 additions and 143 deletions
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tests/attention/test_milestone_gqa_decode_long_ctx_4cases.py
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"""Tests for the long-context decode 4-cases comparative-study bench.
Per ``GQA_full_deck.pptx`` slides 11-17, the 4 cases differ in how KV
cache is sharded across the 8 cubes and 8 PEs of a single KV-head
group on LLaMA-3.1-70B GQA:
Case 1 Cube-SP / PE-TP → KV split by S_kv across cubes; PEs TP on batch
Case 2 Cube-Repl / PE-TP → full KV per cube; PEs TP on batch
Case 3 Cube-Repl / PE-SP → full KV per cube; PEs SP on S_kv (intra-cube AR)
Case 4 Cube-SP / PE-SP → KV split 64-way; 2-phase AR on (m,ℓ,O) ★ optimal
Deviation from slide 13: slide prescribes AllReduce on (m,ℓ,O); the
kernel does reduce-to-root (only the lrab center cube has the answer)
per ADR-0060 §4. Treated as the kernbench Case-4 baseline.
"""
from __future__ import annotations
import re
from pathlib import Path
from kernbench.runtime_api.bench_runner import run_bench
from kernbench.runtime_api.types import resolve_device
from kernbench.sim_engine.engine import GraphEngine
from kernbench.topology.builder import resolve_topology
TOPOLOGY_DEFAULT = Path(__file__).resolve().parents[2] / "topology.yaml"
_CASE4_PANEL = "single_kv_group_decode_long_ctx_gqa_cube_sp_pe_sp"
_CASE3_PANEL = "single_kv_group_decode_long_ctx_gqa_cube_repl_pe_sp"
_CASE2_PANEL = "single_kv_group_decode_long_ctx_gqa_cube_repl_pe_tp"
_CASE1_PANEL = "single_kv_group_decode_long_ctx_gqa_cube_sp_pe_tp"
_CUBE_RE = re.compile(r"\bcube(\d+)\b")
def _engine_factory(t, d):
return GraphEngine(getattr(t, "topology_obj", t), enable_data=True)
def _count(op_log, name: str) -> int:
return sum(1 for r in op_log if r.op_name == name)
def _dma_write_cubes(op_log) -> list[int]:
cubes: list[int] = []
for r in op_log:
if r.op_name != "dma_write":
continue
m = _CUBE_RE.search(r.component_id)
if m is not None:
cubes.append(int(m.group(1)))
return cubes
# ── Case 4 (Cube-SP × PE-SP) — ★ optimal ────────────────────────────
def _run_case4_smoke(*, S_kv: int):
"""Drive the Case 4 decode panel via the case-specific runner.
Uses ``S_kv=8192`` (smoke) to keep test time bounded; the headline
``S_kv=128K`` runs come from ``kernbench run --bench
milestone-gqa-decode-long-ctx-4cases``, not pytest.
"""
from kernbench.benches.milestone_gqa_decode_long_ctx_4cases import (
_run_decode_panel_long_ctx_cube_sp_pe_sp,
)
topo = resolve_topology(str(TOPOLOGY_DEFAULT))
def _bench_fn(ctx):
_run_decode_panel_long_ctx_cube_sp_pe_sp(
ctx, panel=_CASE4_PANEL,
C=8, P=8,
T_q=1, S_kv=S_kv,
d_head=128, h_q=8, h_kv=1,
)
return run_bench(
topology=topo, bench_fn=_bench_fn,
device=resolve_device(None),
engine_factory=_engine_factory,
)
# ── Case 4 — T1: panel is registered in the bench ───────────────────
def test_case4_panel_registered():
"""The Case 4 panel must be in the bench's ``_PANELS`` +
``_PANEL_DISPATCH`` with the expected LLaMA-3.1-70B target dims.
Headline config:
C = 8 (head-parallel CUBE Group)
P = 8 (intra-CUBE PE-SP)
T_q = 1 (decode: one new token per pass)
S_kv = 131_072 (LLaMA long-context decode target)
d_head = 128, h_q = 8, h_kv = 1
The lrab sub_w=4 / sub_h=2 geometry is baked into the Case 4
wrapper kernel; it is not a panel parameter.
"""
from kernbench.benches.milestone_gqa_decode_long_ctx_4cases import (
_PANEL_DISPATCH,
_PANELS,
)
assert _CASE4_PANEL in _PANELS, (
f"{_CASE4_PANEL!r} not in _PANELS; got {_PANELS}"
)
assert _CASE4_PANEL in _PANEL_DISPATCH
kind, params = _PANEL_DISPATCH[_CASE4_PANEL]
assert kind == "decode_long_ctx_cube_sp_pe_sp", (
f"kind={kind!r}, expected 'decode_long_ctx_cube_sp_pe_sp'"
)
assert params.get("C") == 8
assert params.get("P") == 8
assert params.get("T_q") == 1
assert params.get("S_kv") == 131_072
assert params.get("d_head") == 128
assert params.get("h_q") == 8
assert params.get("h_kv") == 1
# ── Case 4 — T2: runner drives the kernel to completion ─────────────
def test_case4_runner_smoke():
"""Case 4 runner drives the new kernel to completion at smoke S_kv."""
result = _run_case4_smoke(S_kv=8192)
assert result.completion.ok, (
f"Case 4 decode smoke at C=8 P=8 must complete; "
f"got {result.completion}"
)
# ── Case 4 — T3: reduce-to-root at the lrab center cube (cube 6) ────
def test_case4_root_at_center_cube_6():
"""For ``sub_w=4, sub_h=2``: root_col=2, root_row=1, root_cube=6.
The decode kernel writes the final O exclusively from PE 0 of cube
6 (ADR-0060 §4 reduce-to-root variant of the Case-4 AR pattern).
"""
result = _run_case4_smoke(S_kv=8192)
assert result.completion.ok
cubes = _dma_write_cubes(result.engine.op_log)
assert cubes, "expected at least one dma_write for the final O store"
distinct = set(cubes)
assert distinct == {6}, (
f"Case 4 root must be the lrab center cube 6; "
f"got cubes={sorted(distinct)}"
)
# ── Case 4 — T4: 2-phase AR ipcq pattern matches Case-4 traffic ─────
def test_case4_two_level_ar_ipcq_pattern():
"""Total ipcq_copy for the Case 4 reduce at (C, P, sub_w) =
(8, 8, 4):
Intra-CUBE (per CUBE = 8 PEs in a 2×4 grid):
row chain along intra_W: cols 1,2,3 each row × 2 rows ×
3 tensors = 18
col bridge along intra_N: pe4 only × 3 tensors = 3
per-CUBE intra total = 21
× 8 CUBEs = 168
Inter-CUBE lrab (sub_w=4, sub_h=2):
Phase 1 row reduce — 3 sends/row × 3 tensors × 2 rows = 18
Phase 2 col reduce — cube 2 → S × 3 tensors = 3
inter-CUBE total = 21
Grand total: 168 + 21 = 189
"""
result = _run_case4_smoke(S_kv=8192)
assert result.completion.ok
n_copy = _count(result.engine.op_log, "ipcq_copy")
assert n_copy == 189, (
f"Case 4 expected 189 ipcq_copy "
f"(168 intra-CUBE + 21 inter-CUBE lrab); got {n_copy}"
)
# ── Case 2 (Cube-Repl × PE-TP) ──────────────────────────────────────
def _run_case2_smoke(*, S_kv: int):
"""Drive the Case 2 decode panel via the case-specific runner.
Case 2 = Cube-Repl × PE-TP. K, V are replicated everywhere (the
slide-11 memory waste); for B=1 only one rank does the work; no
inter-rank comm.
"""
from kernbench.benches.milestone_gqa_decode_long_ctx_4cases import (
_run_decode_panel_long_ctx_cube_repl_pe_tp,
)
topo = resolve_topology(str(TOPOLOGY_DEFAULT))
def _bench_fn(ctx):
_run_decode_panel_long_ctx_cube_repl_pe_tp(
ctx, panel=_CASE2_PANEL,
C=8, P=8,
T_q=1, S_kv=S_kv,
d_head=128, h_q=8, h_kv=1,
)
return run_bench(
topology=topo, bench_fn=_bench_fn,
device=resolve_device(None),
engine_factory=_engine_factory,
)
# ── Case 2 — T1: panel registered ───────────────────────────────────
def test_case2_panel_registered():
"""The Case 2 panel must be in the bench's ``_PANELS`` +
``_PANEL_DISPATCH`` with the expected single-KV-group dims.
Case 2: Cube-Repl × PE-TP. K, V replicated everywhere
(8 KB/tok/PE — slide-11 memory waste); no inter-rank comm.
For B=1 only one rank works (PEs 1-7 idle — slide-11 calls
out this PE-TP waste).
"""
from kernbench.benches.milestone_gqa_decode_long_ctx_4cases import (
_PANEL_DISPATCH,
_PANELS,
)
assert _CASE2_PANEL in _PANELS, (
f"{_CASE2_PANEL!r} not in _PANELS; got {_PANELS}"
)
assert _CASE2_PANEL in _PANEL_DISPATCH
kind, params = _PANEL_DISPATCH[_CASE2_PANEL]
assert kind == "decode_long_ctx_cube_repl_pe_tp"
assert params.get("C") == 8
assert params.get("P") == 8
assert params.get("T_q") == 1
assert params.get("S_kv") == 131_072
assert params.get("d_head") == 128
assert params.get("h_q") == 8
assert params.get("h_kv") == 1
# ── Case 2 — T2: smoke runner completes ─────────────────────────────
def test_case2_runner_smoke():
"""Case 2 runner drives the new kernel to completion at smoke S_kv."""
result = _run_case2_smoke(S_kv=8192)
assert result.completion.ok, (
f"Case 2 decode smoke at C=8 P=8 must complete; "
f"got {result.completion}"
)
# ── Case 2 — T3: zero inter-rank comm by design ─────────────────────
def test_case2_zero_ipcq_copy_no_comm():
"""Case 2's defining property: full KV per rank ⇒ NO inter-rank
communication. Slide 11 lists comm cost as 'none'.
"""
result = _run_case2_smoke(S_kv=8192)
assert result.completion.ok
n_copy = _count(result.engine.op_log, "ipcq_copy")
assert n_copy == 0, (
f"Case 2 must have zero inter-rank comm; got ipcq_copy={n_copy}"
)
# ── Case 2 — T4: single dma_write from cube 0 (B=1 single-rank work) ─
def test_case2_single_dma_write_at_cube_0():
"""For B=1, only PE 0 of CUBE 0 does the work (the inherent PE-TP
waste at B=1). Exactly 1 dma_write, from cube 0.
"""
result = _run_case2_smoke(S_kv=8192)
assert result.completion.ok
cubes = _dma_write_cubes(result.engine.op_log)
assert cubes, "expected at least one dma_write for the final O store"
distinct = set(cubes)
assert distinct == {0}, (
f"Case 2 B=1 single writer must be cube 0; "
f"got cubes={sorted(distinct)}"
)
# ── Case 3 (Cube-Repl × PE-SP) ──────────────────────────────────────
def _run_case3_smoke(*, S_kv: int):
"""Drive the Case 3 decode panel via the case-specific runner.
Case 3 = Cube-Repl × PE-SP. K, V replicated per cube; S_kv split
8-way across PEs within each cube. Intra-CUBE 8-way reduce on
(m, ℓ, O); no inter-CUBE comm (every cube ends with full answer).
"""
from kernbench.benches.milestone_gqa_decode_long_ctx_4cases import (
_run_decode_panel_long_ctx_cube_repl_pe_sp,
)
topo = resolve_topology(str(TOPOLOGY_DEFAULT))
def _bench_fn(ctx):
_run_decode_panel_long_ctx_cube_repl_pe_sp(
ctx, panel=_CASE3_PANEL,
C=8, P=8,
T_q=1, S_kv=S_kv,
d_head=128, h_q=8, h_kv=1,
)
return run_bench(
topology=topo, bench_fn=_bench_fn,
device=resolve_device(None),
engine_factory=_engine_factory,
)
# ── Case 3 — T1: panel registered ───────────────────────────────────
def test_case3_panel_registered():
"""The Case 3 panel must be in the bench's ``_PANELS`` +
``_PANEL_DISPATCH`` with the expected single-KV-group dims.
Case 3: Cube-Repl × PE-SP. K, V replicated per cube; PEs SP on
S_kv. Intra-CUBE 8-way AR; no inter-CUBE comm.
"""
from kernbench.benches.milestone_gqa_decode_long_ctx_4cases import (
_PANEL_DISPATCH,
_PANELS,
)
assert _CASE3_PANEL in _PANELS, (
f"{_CASE3_PANEL!r} not in _PANELS; got {_PANELS}"
)
assert _CASE3_PANEL in _PANEL_DISPATCH
kind, params = _PANEL_DISPATCH[_CASE3_PANEL]
assert kind == "decode_long_ctx_cube_repl_pe_sp"
assert params.get("C") == 8
assert params.get("P") == 8
assert params.get("T_q") == 1
assert params.get("S_kv") == 131_072
assert params.get("d_head") == 128
assert params.get("h_q") == 8
assert params.get("h_kv") == 1
# ── Case 3 — T2: smoke runner completes ─────────────────────────────
def test_case3_runner_smoke():
"""Case 3 runner drives the new kernel to completion at smoke S_kv."""
result = _run_case3_smoke(S_kv=8192)
assert result.completion.ok, (
f"Case 3 decode smoke at C=8 P=8 must complete; "
f"got {result.completion}"
)
# ── Case 3 — T3: intra-CUBE-only AR (168 ipcq, no inter-CUBE) ───────
def test_case3_intra_cube_ar_only_ipcq():
"""Case 3 reduce pattern: per-CUBE 8-way PE-SP AR (same structural
cost as Case 4's intra-CUBE phase = 21 ipcq_copy per cube), and
NO inter-CUBE traffic (each cube has a full copy of KV).
per-CUBE intra (2×4 PE grid):
row chain along intra_W: cols 1,2,3 each row × 2 rows ×
3 tensors (m, ℓ, O) = 18
col bridge along intra_N: pe4 only × 3 tensors = 3
per-CUBE intra total = 21
× 8 CUBEs = 168
inter-CUBE: 0 (replicated KV ⇒ no AllReduce needed).
Grand total: 168.
"""
result = _run_case3_smoke(S_kv=8192)
assert result.completion.ok
n_copy = _count(result.engine.op_log, "ipcq_copy")
assert n_copy == 168, (
f"Case 3 expected 168 ipcq_copy (intra-CUBE only, no inter-CUBE); "
f"got {n_copy}"
)
# ── Case 3 — T4: single dma_write from cube 0 (designated writer) ───
def test_case3_single_dma_write_at_cube_0():
"""Every cube ends with the full answer after intra-CUBE AR; only
the designated writer (cube 0, PE 0) stores O to avoid 8 redundant
DMAs.
"""
result = _run_case3_smoke(S_kv=8192)
assert result.completion.ok
cubes = _dma_write_cubes(result.engine.op_log)
assert cubes, "expected at least one dma_write for the final O store"
distinct = set(cubes)
assert distinct == {0}, (
f"Case 3 designated writer must be cube 0; "
f"got cubes={sorted(distinct)}"
)
# ── Case 1 (Cube-SP × PE-TP) ────────────────────────────────────────
def _run_case1_smoke(*, S_kv: int):
"""Drive the Case 1 decode panel via the case-specific runner.
Case 1 = Cube-SP × PE-TP. K, V split S_kv-wise across the 8 cubes
(cube=row_wise), replicated within each cube (pe=replicate). PEs
nominally split on the batch dim (PE-TP); at B=1 only PE 0 of
each cube has work; PEs 1-7 idle. Inter-CUBE 8-way reduce via the
lrab-adapted center-root pattern (root cube 6); no intra-CUBE comm.
"""
from kernbench.benches.milestone_gqa_decode_long_ctx_4cases import (
_run_decode_panel_long_ctx_cube_sp_pe_tp,
)
topo = resolve_topology(str(TOPOLOGY_DEFAULT))
def _bench_fn(ctx):
_run_decode_panel_long_ctx_cube_sp_pe_tp(
ctx, panel=_CASE1_PANEL,
C=8, P=8,
T_q=1, S_kv=S_kv,
d_head=128, h_q=8, h_kv=1,
)
return run_bench(
topology=topo, bench_fn=_bench_fn,
device=resolve_device(None),
engine_factory=_engine_factory,
)
# ── Case 1 — T1: panel registered ───────────────────────────────────
def test_case1_panel_registered():
"""The Case 1 panel must be in the bench's ``_PANELS`` +
``_PANEL_DISPATCH`` with the expected single-KV-group dims.
Case 1: Cube-SP × PE-TP. K, V split across cubes; PEs TP on
batch. At B=1 only PE 0 of each cube works (PE-TP waste).
Inter-CUBE lrab AR; no intra-CUBE comm.
"""
from kernbench.benches.milestone_gqa_decode_long_ctx_4cases import (
_PANEL_DISPATCH,
_PANELS,
)
assert _CASE1_PANEL in _PANELS, (
f"{_CASE1_PANEL!r} not in _PANELS; got {_PANELS}"
)
assert _CASE1_PANEL in _PANEL_DISPATCH
kind, params = _PANEL_DISPATCH[_CASE1_PANEL]
assert kind == "decode_long_ctx_cube_sp_pe_tp"
assert params.get("C") == 8
assert params.get("P") == 8
assert params.get("T_q") == 1
assert params.get("S_kv") == 131_072
assert params.get("d_head") == 128
assert params.get("h_q") == 8
assert params.get("h_kv") == 1
# ── Case 1 — T2: smoke runner completes ─────────────────────────────
def test_case1_runner_smoke():
"""Case 1 runner drives the new kernel to completion at smoke S_kv."""
result = _run_case1_smoke(S_kv=8192)
assert result.completion.ok, (
f"Case 1 decode smoke at C=8 P=8 must complete; "
f"got {result.completion}"
)
# ── Case 1 — T3: inter-CUBE lrab only (21 ipcq, no intra-CUBE) ──────
def test_case1_inter_cube_lrab_only_ipcq():
"""Case 1 reduce pattern: only PE 0 of each cube has work (PE-TP
at B=1), so NO intra-CUBE AR. Inter-CUBE 8-way reduce uses the
lrab-adapted center-root pattern (same structural cost as Case 4's
inter-CUBE phase).
Inter-CUBE lrab (sub_w=4, sub_h=2):
Phase 1 row reduce — 3 sends/row × 3 tensors × 2 rows = 18
Phase 2 col reduce — cube 2 → S × 3 tensors = 3
inter-CUBE total = 21
Intra-CUBE: 0 (PEs 1-7 idle, no partials to merge).
Grand total: 21.
"""
result = _run_case1_smoke(S_kv=8192)
assert result.completion.ok
n_copy = _count(result.engine.op_log, "ipcq_copy")
assert n_copy == 21, (
f"Case 1 expected 21 ipcq_copy (inter-CUBE lrab only, no intra-CUBE); "
f"got {n_copy}"
)
# ── Case 1 — T4: root at lrab center cube 6 ─────────────────────────
def test_case1_root_at_center_cube_6():
"""Case 1 uses the same lrab-adapted center-root reduce as Case 4's
inter-CUBE phase; the answer lands at the lrab center cube
(sub_w=4, sub_h=2 → root_col=2, root_row=1 → root_cube=6).
"""
result = _run_case1_smoke(S_kv=8192)
assert result.completion.ok
cubes = _dma_write_cubes(result.engine.op_log)
assert cubes, "expected at least one dma_write for the final O store"
distinct = set(cubes)
assert distinct == {6}, (
f"Case 1 root must be the lrab center cube 6; "
f"got cubes={sorted(distinct)}"
)