[EPLB] Optimize EPLB with numpy (#29499)

Signed-off-by: ilmarkov <markovilya197@gmail.com>
Co-authored-by: Tyler Michael Smith <tyler@neuralmagic.com>
This commit is contained in:
Ilya Markov
2026-01-07 21:21:35 +01:00
committed by GitHub
parent 0ada960a20
commit 6170d47d22
8 changed files with 732 additions and 266 deletions

View File

@@ -310,3 +310,143 @@ if __name__ == "__main__":
print(phy2log)
test_basic_rebalance()
def _make_phy_replicas_idx_from_phy2log(phy2log: torch.Tensor) -> torch.Tensor:
"""Create replicas indices mapping from phy2log"""
pr = torch.zeros_like(phy2log)
for layer in range(phy2log.shape[0]):
seen: dict[int, int] = {}
row = phy2log[layer].tolist()
for i, expert in enumerate(row):
r = seen.get(expert, 0)
pr[layer, i] = r
seen[expert] = r + 1
return pr
def _validate_intragpu_rearrangement(
old_global_expert_indices: torch.Tensor,
new_phy2log: torch.Tensor,
new_phy_replicas_idx: torch.Tensor,
post_phy2log: torch.Tensor,
post_phy_replicas_idx: torch.Tensor,
num_ranks: int,
slots_per_gpu: int,
):
# Per-GPU checks
for gpu_idx in range(num_ranks):
start = gpu_idx * slots_per_gpu
end = start + slots_per_gpu
old_seg = old_global_expert_indices[0, start:end]
new_seg = new_phy2log[0, start:end]
new_rnk = new_phy_replicas_idx[0, start:end]
post_seg = post_phy2log[0, start:end]
post_rnk = post_phy_replicas_idx[0, start:end]
# Pairwise equality for (expert, rank) pairs to ensure nothing is lost
def sorted_pairs(seg: torch.Tensor, rnk: torch.Tensor):
pairs = list(zip(seg.tolist(), rnk.tolist()))
pairs.sort()
return pairs
assert sorted_pairs(post_seg, post_rnk) == sorted_pairs(new_seg, new_rnk), (
f"Per-GPU pairs of (expert,rank) must match new mapping for GPU {gpu_idx}"
)
# For experts that remain on the same GPU, the old slot is preserved
# for at least one occurrence; rank at that slot must be valid for that expert
old_list = old_seg.tolist()
new_list = new_seg.tolist()
post_list = post_seg.tolist()
remained = set(old_list) & set(new_list)
new_ranks_for_expert: dict[int, list[int]] = {}
for v, r in zip(new_list, new_rnk.tolist()):
new_ranks_for_expert.setdefault(v, []).append(r)
for expert in remained:
old_pos = old_list.index(expert)
assert post_list[old_pos] == expert, (
f"Expert {expert} on GPU {gpu_idx} should stay at old slot {old_pos}"
)
# Rank at preserved slot must be one of the ranks
# the expert has in new mapping
assert post_rnk.tolist()[old_pos] in new_ranks_for_expert[expert], (
f"Rank for expert {expert} at preserved slot on GPU {gpu_idx} "
"must come from new mapping"
)
@pytest.mark.parametrize(
"num_ranks, slots_per_gpu, old_phy2log, new_phy2log",
[
pytest.param(
# Setup: 2 GPUs, 4 slots each, 1 layer
# Old mapping: GPU0 -> [0,1,2,3], GPU1 -> [4,5,6,7]
# New mapping shuffles within GPU0 and brings 4,5 into GPU0.
# GPU0 new -> [1,5,0,4]; GPU1 new -> [6,2,7,3]
2,
4,
torch.tensor([[0, 1, 2, 3, 4, 5, 6, 7]]),
torch.tensor([[1, 5, 0, 4, 6, 2, 7, 3]]),
id="simple",
),
pytest.param(
# Setup: 2 GPUs, 5 slots each (total 10 physical experts), 1 layer
# Old mapping:
# GPU0 -> [0, 1, 0, 2, 3] (expert 0 duplicated)
# GPU1 -> [4, 5, 6, 1, 2]
# New mapping reorders within GPUs and moves some experts across GPUs,
# while still including duplicates:
# GPU0 new -> [0, 5, 4, 0, 1] (expert 0 duplicated, 4/5 incoming)
# GPU1 new -> [6, 2, 3, 2, 1] (expert 2 duplicated)
2,
5,
torch.tensor([[0, 1, 0, 2, 3, 4, 5, 6, 1, 2]]),
torch.tensor([[0, 5, 4, 0, 1, 6, 2, 3, 2, 1]]),
id="duplicates",
),
pytest.param(
# Setup: 3 GPUs, 4 slots each (total 12 physical experts), 1 layer
# Old mapping:
# GPU0 -> [0, 1, 2, 3]
# GPU1 -> [0, 1, 2, 3]
# GPU2 -> [0, 1, 2, 3]
# New mapping decides to use one expert on 2 GPUs and shuffles
# experts on the third GPU,
# GPU0 new -> [0, 0, 0, 0]
# GPU1 new -> [0, 0, 0, 0]
# GPU2 new -> [1, 2, 3, 0]
3,
4,
torch.tensor([[0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3]]),
torch.tensor([[0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 0]]),
id="skewed_expert",
),
],
)
def test_preserve_intragpu_slots(
num_ranks: int,
slots_per_gpu: int,
old_phy2log: torch.Tensor,
new_phy2log: torch.Tensor,
):
"""Experts that stay on a GPU keep their old slots; incoming not lost."""
phy_replicas_idx = _make_phy_replicas_idx_from_phy2log(new_phy2log)
post_phy2log, post_phy_replicas_idx = DefaultEplbPolicy.preserve_intragpu_slots(
new_phy2log, phy_replicas_idx, num_ranks, old_phy2log
)
# Shapes preserved
assert post_phy2log.shape == new_phy2log.shape
assert post_phy_replicas_idx.shape == phy_replicas_idx.shape
_validate_intragpu_rearrangement(
old_phy2log,
new_phy2log,
phy_replicas_idx,
post_phy2log,
post_phy_replicas_idx,
num_ranks,
slots_per_gpu,
)

View File

@@ -286,15 +286,17 @@ def _test_async_transfer_layer_without_mtp_worker(
device,
old_indices,
)
old_indices_cpu = old_indices.cpu()
new_indices_cpu = new_indices.cpu()
expert_buffer = [torch.empty_like(w) for w in expert_weights[0]]
cuda_stream = torch.cuda.Stream(device=device)
for layer_idx in range(num_layers):
is_unchanged, is_received_locally, experts_recv_loc = asyncio.run(
is_unchanged, is_received_locally, recv_metadata = asyncio.run(
transfer_layer(
old_global_expert_indices=old_indices,
new_global_expert_indices=new_indices,
old_global_expert_indices=old_indices_cpu,
new_global_expert_indices=new_indices_cpu,
expert_weights=expert_weights,
expert_weights_buffer=expert_buffer,
ep_group=ep_group,
@@ -302,16 +304,15 @@ def _test_async_transfer_layer_without_mtp_worker(
cuda_stream=cuda_stream,
)
)
cuda_stream.synchronize()
move_from_buffer(
expert_weights=expert_weights[layer_idx],
expert_weights_buffer=expert_buffer,
expert_weights_buffers=expert_buffer,
is_unchanged=is_unchanged,
is_received_locally=is_received_locally,
experts_recv_loc=experts_recv_loc,
new_indices=new_indices[layer_idx].tolist(),
ep_group=ep_group,
recv_metadata=recv_metadata,
new_indices=new_indices_cpu[layer_idx],
ep_rank=ep_rank,
)
verify_expert_weights_after_shuffle(