Files
kernbench2/tests/test_tp_layers.py
T
ywkang 105f1dc09e ADR-0027: Megatron TP API + worker-wait generalization + mp.spawn
Implements ADR-0027 Phase 2 end-to-end. All 559 tests pass (was 523 +
1 xfail; ring_default_ws strict-xfail is now resolved).

D0 — Worker-wait generalization (context.py):
- _pending_worker_waits queue on RuntimeContext.
- ctx.wait(h) in worker context defers to main via g.parent.switch().
  Fast-path for already-completed handles.
- Worker API is unchanged: tensor deploy, launch, etc. still look
  synchronous; they're transparently cooperatively scheduled.
- Solves ADR-0024 Phase B kernel-greenlet orphan bug (env.run now
  only ever drives from main; kernel _parent is always main).

D0.5 — Host-read barrier (tensor.py):
- Explicit _HOST_READ_BARRIERS registry (T5.g closed-set via code
  review, not reflection-magic).
- numpy/data/__getitem__/__repr__ drain pending worker-waits before
  host-observable read.
- copy_: source-side barrier via source.numpy(). Target-side write
  barrier is intentionally NOT applied — global pending target barrier
  prematurely drains cross-rank collectives → deadlock.
- Collective pending is excluded from barrier drain condition
  (collective is cross-rank; its own yield in all_reduce covers the
  invariant naturally).

D1 — torch.multiprocessing.spawn (runtime_api/multiprocessing.py):
- API signature parity with real PyTorch spawn; execution is
  cooperative greenlet scheduler (process isolation etc. are explicit
  non-goals per D1.0).
- _drain_pending drains worker-waits then collectives in one barrier,
  loop-until-empty.
- Round-based exception handling with SystemExit sibling abort +
  SpawnException(errors) wrapping root-cause ranks.
- RuntimeContext attaches ctx.multiprocessing in __post_init__.
- benches/ccl_allreduce.py hand-rolled loop collapses to one
  torch.multiprocessing.spawn call.

D2–D6 — kernbench.tp package:
- parallel_state: initialize_model_parallel, get_*_rank,
  get_*_world_size, with weak active-ctx registry in context.py.
- layers: ColumnParallelLinear, RowParallelLinear (shape-only
  primitives — fp16 gemm via tl.load + tl.dot + tl.store).
- kernels: _gemm_kernel used by TP layers (self-contained; no bench
  dependency).
- primitives / mappings stubs per D6/D8.

Data-path fixes (surfaced by TP gemm + all_reduce sequence):
- sim_engine/op_log.py: dma_write snapshot is skipped for TCM
  sources (PE scratch is repopulated by Phase 2 math/gemm replay —
  capturing Phase-1-time snapshot picked up STALE data from prior
  kernel's output aliased at the same scratch addr, causing the later
  kernel's dma_write to overwrite Phase 2 result with stale value).
- sim_engine/op_log.py + sim_engine/data_executor.py: per-operand
  space recorded on GemmCmd and composite gemm records so HBM-resident
  operands (tl.load output) don't default to TCM during replay.
- runtime_api/context.py: ctx.zeros writes zero-init to MemoryStore
  at VA keys so kernels reading via VA see deterministic init even
  without explicit copy_().

Tests (Phase 1 + Phase 2):
- test_worker_wait_drain (T3): orphan invariant + resume + multi-rank
  drain + idempotency + exception propagation.
- test_mp_spawn (T4): spawn shape + bind + SpawnException scope.
- test_host_read_barrier (T5): barrier contract per entry-point +
  closed-set registry check.
- test_tp_parallel_state (T1): initialize + rank lookup.
- test_tp_layers (T2): shape + deterministic numerical correctness
  (concat-matmul equality for RowParallel, not mean-only).
- test_tp_mlp (T6): full 2-layer MLP with deterministic weight
  numerical match + rank-consistency post all-reduce.
- test_ccl_allreduce_matrix: ring_default_ws xfail removed (T7).

Regression: 523 pre + 35 new + 1 ex-xfail = 559 passed, 1 intentional
skip (T3.e historical failure documentation).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-04-14 16:31:13 -07:00

235 lines
8.4 KiB
Python

"""ADR-0027 T2: TP layer shape + numerical correctness (D4/D5).
Phase 1: ``kernbench.tp.layers`` doesn't exist → import failure. Phase 2
lands D4/D5 and T2 passes with deterministic non-zero weight patterns.
"""
from __future__ import annotations
import numpy as np
import pytest
def _make_ctx(topology):
from kernbench.runtime_api.context import RuntimeContext
from kernbench.runtime_api.types import DeviceSelector
from kernbench.sim_engine.engine import GraphEngine
engine = GraphEngine(topology.topology_obj, enable_data=True)
return RuntimeContext(
engine=engine,
target_device=DeviceSelector("all"),
correlation_id="test_t2",
spec=topology.topology_obj.spec,
)
# ── Shape / structural ───────────────────────────────────────────────
def test_column_parallel_weight_shape_per_rank(topology):
"""ColumnParallelLinear weight per rank is (in_features, out // ws)."""
import kernbench.tp as tp
from kernbench.runtime_api.tensor import Tensor
with _make_ctx(topology) as ctx:
ctx.distributed.init_process_group(backend="ahbm")
ws = ctx.distributed.get_world_size()
tp.initialize_model_parallel(ws)
def _worker(rank: int):
ctx.ahbm.set_device(rank)
fc = tp.ColumnParallelLinear(
in_features=256, out_features=512, torch=ctx,
)
assert fc.weight.shape == (256, 512 // ws)
ctx.multiprocessing.spawn(_worker, args=(), nprocs=ws)
def test_row_parallel_weight_shape_per_rank(topology):
"""RowParallelLinear weight per rank is (in_features // ws, out_features)."""
import kernbench.tp as tp
with _make_ctx(topology) as ctx:
ctx.distributed.init_process_group(backend="ahbm")
ws = ctx.distributed.get_world_size()
tp.initialize_model_parallel(ws)
def _worker(rank: int):
ctx.ahbm.set_device(rank)
fc = tp.RowParallelLinear(
in_features=512, out_features=256, torch=ctx,
)
assert fc.weight.shape == (512 // ws, 256)
ctx.multiprocessing.spawn(_worker, args=(), nprocs=ws)
# ── T2.a: ColumnParallel deterministic numerical ─────────────────────
def test_column_parallel_forward_matches_matmul(topology):
"""T2.a: ColumnParallelLinear.forward output == x @ W_rank (rtol 1e-2)."""
import kernbench.tp as tp
from kernbench.runtime_api.tensor import Tensor
with _make_ctx(topology) as ctx:
ctx.distributed.init_process_group(backend="ahbm")
ws = ctx.distributed.get_world_size()
tp.initialize_model_parallel(ws)
M = 4
D_in, D_out = 32, 32 * ws
def _worker(rank: int):
ctx.ahbm.set_device(rank)
fc = tp.ColumnParallelLinear(
in_features=D_in, out_features=D_out, torch=ctx,
)
# Deterministic non-zero weight: rank-scaled constant.
k_local = D_out // ws
weight_np = np.full(
(D_in, k_local), 0.01 * (rank + 1), dtype=np.float16,
)
src = Tensor(shape=(D_in, k_local), dtype="f16", name="host_w")
src._host_buffer = weight_np
fc.weight.copy_(src)
# Input: full-replicated constant.
x_np = np.full((M, D_in), 0.5, dtype=np.float16)
x = ctx.zeros(
(M, D_in), dtype="f16",
dp=_replicate_dp(), name=f"t2a_x_r{rank}",
)
hx = Tensor(shape=x_np.shape, dtype="f16", name="host_x")
hx._host_buffer = x_np
x.copy_(hx)
y = fc.forward(x)
out = y.numpy()
expected = x_np.astype(np.float32) @ weight_np.astype(np.float32)
assert out.shape == (M, k_local)
assert np.allclose(out.astype(np.float32), expected,
rtol=1e-2, atol=1e-2), (
f"rank {rank}: output does not match x @ W_local"
)
ctx.multiprocessing.spawn(_worker, args=(), nprocs=ws)
# ── T2.b: RowParallel observable equality ────────────────────────────
def test_row_parallel_forward_concat_matmul_equality(topology):
"""T2.b (primary): RowParallel output == concat(x) @ concat(W) (all-reduced)."""
import kernbench.tp as tp
from kernbench.runtime_api.tensor import Tensor
with _make_ctx(topology) as ctx:
ctx.distributed.init_process_group(backend="ahbm")
ws = ctx.distributed.get_world_size()
tp.initialize_model_parallel(ws)
M = 4
D_in, D_out = 32 * ws, 32 # must divide ws evenly
results: dict[int, np.ndarray] = {}
def _worker(rank: int):
ctx.ahbm.set_device(rank)
fc = tp.RowParallelLinear(
in_features=D_in, out_features=D_out, torch=ctx,
)
# Per-rank W_k = constant 0.01 * (rank + 1)
n_local = D_in // ws
weight_np = np.full(
(n_local, D_out), 0.01 * (rank + 1), dtype=np.float16,
)
src = Tensor(shape=weight_np.shape, dtype="f16", name="host_w")
src._host_buffer = weight_np
fc.weight.copy_(src)
# Input x_k = constant 0.1 * (rank + 1) (pretending it was
# column-sharded from upstream).
x_np = np.full((M, n_local), 0.1 * (rank + 1), dtype=np.float16)
x = ctx.zeros(
(M, n_local), dtype="f16",
dp=_replicate_dp(), name=f"t2b_x_r{rank}",
)
hx = Tensor(shape=x_np.shape, dtype="f16", name="host_x")
hx._host_buffer = x_np
x.copy_(hx)
y = fc.forward(x)
results[rank] = y.numpy().astype(np.float32)
ctx.multiprocessing.spawn(_worker, args=(), nprocs=ws)
# Host-side reference: compute sum_r (x_r @ W_r) = y (same on all ranks).
expected = np.zeros((M, D_out), dtype=np.float32)
n_local = D_in // ws
for r in range(ws):
x_r = np.full((M, n_local), 0.1 * (r + 1), dtype=np.float32)
w_r = np.full((n_local, D_out), 0.01 * (r + 1), dtype=np.float32)
expected += x_r @ w_r
for r, out in results.items():
assert np.allclose(out, expected, rtol=1e-2, atol=1e-2), (
f"rank {r}: all-reduced output != expected partial sum"
)
# ── T2.c: rank-consistency post all-reduce ───────────────────────────
def test_row_parallel_rank_identity_post_all_reduce(topology):
"""T2.c: after all_reduce, all ranks see elementwise-identical output."""
import kernbench.tp as tp
from kernbench.runtime_api.tensor import Tensor
with _make_ctx(topology) as ctx:
ctx.distributed.init_process_group(backend="ahbm")
ws = ctx.distributed.get_world_size()
tp.initialize_model_parallel(ws)
M = 2
D_in, D_out = 16 * ws, 16
results: dict[int, np.ndarray] = {}
def _worker(rank: int):
ctx.ahbm.set_device(rank)
fc = tp.RowParallelLinear(
in_features=D_in, out_features=D_out, torch=ctx,
)
n_local = D_in // ws
weight_np = np.full((n_local, D_out), 0.01, dtype=np.float16)
src = Tensor(shape=weight_np.shape, dtype="f16", name="host_w")
src._host_buffer = weight_np
fc.weight.copy_(src)
x_np = np.full((M, n_local), 0.1, dtype=np.float16)
x = ctx.zeros(
(M, n_local), dtype="f16",
dp=_replicate_dp(), name=f"t2c_x_r{rank}",
)
hx = Tensor(shape=x_np.shape, dtype="f16", name="host_x")
hx._host_buffer = x_np
x.copy_(hx)
y = fc.forward(x)
results[rank] = y.numpy()
ctx.multiprocessing.spawn(_worker, args=(), nprocs=ws)
ref = results[0]
for r, out in results.items():
assert np.allclose(out, ref, rtol=1e-2, atol=1e-2), (
f"rank {r} output differs from rank 0 — all_reduce failed to make "
f"outputs elementwise identical"
)
def _replicate_dp():
from kernbench.policy.placement.dp import DPPolicy
return DPPolicy(cube="replicate", pe="replicate", num_cubes=1, num_pes=1)