[moe training] Add TP support for routed experts (#2473)

add tp support for fp8 moe training

Author: danielvegamyhre

test/prototype/moe_training/test_fsdp.py

@@ -16,9 +16,10 @@
 
 from torchao.float8.float8_utils import compute_error
 from torchao.prototype.moe_training.conversion_utils import MoETrainingConfig
-from torchao.prototype.moe_training.tensor import ScaledGroupedMMTensor
 from torchao.quantization.quant_api import quantize_
 
+from .testing_utils import _validate_model_conversion
+
 # this test requires torchtitan
 try:
     from torchtitan.experiments.llama4.model.args import TransformerModelArgs
@@ -119,36 +120,6 @@ def moe_module_filter_fn(mod: nn.Module, cur_fqn: str) -> bool:
     dist.destroy_process_group()
 
 
-def _validate_model_conversion(
-    root_module: nn.Module,
-    target_fqns: list[str],
-):
-    def _recursive_validate(
-        module: nn.Module,
-        cur_fqn: str,
-    ):
-        is_allowed_module = cur_fqn in target_fqns
-
-        # check current module params
-        for param_name, param in module.named_parameters(recurse=False):
-            is_converted_type = isinstance(param, ScaledGroupedMMTensor)
-            if is_converted_type:
-                assert is_allowed_module, (
-                    f"Module {cur_fqn} is not in target_fqns, but has converted param {param_name}."
-                )
-            if not is_allowed_module:
-                assert not is_converted_type, (
-                    f"Module {cur_fqn} is not in target_fqns, but has converted param {param_name}."
-                )
-
-        # recursively check child modules
-        for child_name, child_module in module.named_children():
-            child_fqn = f"{cur_fqn}.{child_name}" if cur_fqn else child_name
-            _recursive_validate(child_module, child_fqn)
-
-    _recursive_validate(root_module, "")
-
-
 def setup_distributed():
     rank = int(os.environ["RANK"])
     world_size = int(os.environ["WORLD_SIZE"])

test/prototype/moe_training/test_fsdp.sh

@@ -1 +1 @@
-torchrun --nproc_per_node=2 --local-ranks-filter=0 -m pytest test/prototype/moe_training/test_fsdp.py
+torchrun --nproc_per_node=2 --local-ranks-filter=0 -m pytest test/prototype/moe_training/test_fsdp.py -s

test/prototype/moe_training/test_tp.py

@@ -0,0 +1,245 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD 3-Clause license found in the
+# LICENSE file in the root directory of this source tree.
+######################################################################
+#
+# To run these unit tests, use the following command:
+#
+# torchrun --nproc_per_node=${NUM_GPUS} -m pytest test_tp.py
+#
+#######################################################################
+
+import copy
+import os
+
+import pytest
+import torch
+from torch import distributed as dist
+from torch import nn
+from torch.distributed._tensor import DTensor
+from torch.distributed.device_mesh import DeviceMesh, init_device_mesh
+from torch.distributed.tensor import Partial, Replicate, Shard
+from torch.nn import functional as F
+
+try:
+    from torch.distributed.tensor.parallel import (
+        PrepareModuleInputOutput,
+        parallelize_module,
+    )
+except ImportError:
+    import warnings
+
+    warnings.warn(
+        "torch version is too old, these tests require nightly build. Skipping MoE training tests."
+    )
+    pytest.skip(allow_module_level=True)
+
+
+# this feature requires CUDA and SM89+
+if not torch.cuda.is_available() or torch.cuda.get_device_capability() < (8, 9):
+    pytest.skip(
+        "CUDA not available or compute capability < 8.9", allow_module_level=True
+    )
+
+from torchao.float8.float8_utils import compute_error
+from torchao.prototype.moe_training.conversion_utils import MoETrainingConfig
+from torchao.quantization.quant_api import quantize_
+
+from .testing_utils import _validate_model_conversion
+
+# this test requires torchtitan
+try:
+    from torchtitan.experiments.llama4.infra.expert_parallel import (
+        ExpertParallel,
+        ExpertTensorParallel,
+        NoParallel,
+        TensorParallel,
+    )
+    from torchtitan.experiments.llama4.model.args import TransformerModelArgs
+    from torchtitan.experiments.llama4.model.moe import MoE
+except ImportError:
+    import warnings
+
+    warnings.warn("torchtitan not installed, skipping MoE tests.")
+    pytest.skip(allow_module_level=True)
+
+
+@pytest.mark.parametrize(
+    "target_fqns",
+    [
+        ["experts"],
+        # TODO: investigate hang when shared_expert is converted
+        # ["experts,shared_expert"],
+    ],
+)
+def test_moe_float8_training_tp(target_fqns: list[str]):
+    assert torch.cuda.is_available()
+
+    # setup distributed for tp
+    mesh = setup_distributed()
+
+    # define model args
+    model_args = TransformerModelArgs(
+        moe_enabled=True,
+        num_experts=8,
+        dim=256,
+        vocab_size=1024,
+    )
+    init_std = 0.02
+    device = torch.device("cuda")
+
+    # reference bf16 MoE
+    ref_model = MoE(model_args).to(torch.bfloat16).cuda()
+    torch.manual_seed(1)
+    ref_model.init_weights(init_std, device)
+
+    # target MoE for testing conversion
+    model = copy.deepcopy(ref_model)
+
+    # assert starting params are identical for both models
+    for param1, param2 in zip(model.parameters(), ref_model.parameters()):
+        assert torch.equal(param1, param2)
+
+    # convert MoE to float8 training
+    def moe_module_filter_fn(mod: nn.Module, cur_fqn: str) -> bool:
+        for target_fqn in target_fqns:
+            if target_fqn in cur_fqn:
+                return True
+        return False
+
+    # quantize test model
+    config = MoETrainingConfig()
+    quantize_(model, config=config, filter_fn=moe_module_filter_fn)
+
+    # validate that only the experts were converted
+    _validate_model_conversion(
+        model,
+        target_fqns=target_fqns,
+    )
+
+    # apply TP
+    apply_moe_ep_tp(model, tp_mesh=mesh, ep_mesh=None, ep_tp_mesh=None)
+    apply_moe_ep_tp(ref_model, tp_mesh=mesh, ep_mesh=None, ep_tp_mesh=None)
+
+    # Rough validation that parallelization was applied properly.
+    assert isinstance(model.experts.w1.data, DTensor), (
+        "test model experts.w1 is not a DTensor"
+    )
+    assert isinstance(model.experts.w2.data, DTensor), (
+        "test model experts.w2 is not a DTensor"
+    )
+    assert isinstance(model.experts.w3.data, DTensor), (
+        "test model experts.w3 is not a DTensor"
+    )
+    assert isinstance(ref_model.experts.w1.data, DTensor), (
+        "ref model experts.w1 is not a DTensor"
+    )
+    assert isinstance(ref_model.experts.w2.data, DTensor), (
+        "ref model experts.w2 is not a DTensor"
+    )
+    assert isinstance(ref_model.experts.w3.data, DTensor), (
+        "ref model experts.w3 is not a DTensor"
+    )
+
+    # inputs
+    batch, seq, dim = 8, 2048, 256
+    ref_x = torch.randn(
+        batch, seq, dim, dtype=torch.bfloat16, requires_grad=True, device=device
+    )
+    x = ref_x.detach().clone().requires_grad_(True)
+
+    # forward pass
+    ref_out = ref_model(ref_x)
+    out = model(x)
+
+    # validate output
+    out_sqnr = compute_error(out, ref_out)
+    assert out_sqnr.item() >= 30.0, f"SQNR must be >= 30.0, got {out_sqnr.item()}."
+
+    # compute loss
+    labels = torch.ones_like(ref_out)
+    ref_loss = F.mse_loss(ref_out, labels)
+    out_loss = F.mse_loss(out, labels)
+
+    # backward pass
+    ref_loss.backward()
+    out_loss.backward()
+
+    # validate input gradient
+    input_grad_sqnr = compute_error(x.grad, ref_x.grad)
+    assert input_grad_sqnr.item() >= 28.0, (
+        f"SQNR must be >= 28.0, got {input_grad_sqnr.item()}."
+    )
+
+    # validate param gradients
+    for param1, param2 in zip(model.parameters(), ref_model.parameters()):
+        param_grad_sqnr = compute_error(param1.grad, param2.grad)
+        assert param_grad_sqnr.item() >= 25.0, (
+            f"SQNR must be >= 25.0, got {param_grad_sqnr.item()}."
+        )
+
+    dist.destroy_process_group()
+
+
+def setup_distributed():
+    rank = int(os.environ["RANK"])
+    world_size = int(os.environ["WORLD_SIZE"])
+    dist.init_process_group("nccl", rank=rank, world_size=world_size)
+    device_mesh = init_device_mesh("cuda", (world_size,))
+    # seed must be the same in all processes
+    torch.manual_seed(1)
+    torch.cuda.set_device(rank)
+    return device_mesh
+
+
+def apply_moe_ep_tp(
+    model: nn.Module,
+    tp_mesh: DeviceMesh | None,
+    ep_mesh: DeviceMesh | None,
+    ep_tp_mesh: DeviceMesh | None,
+):
+    # Modified version of moe parallelization from https://github.com/pytorch/torchtitan/pull/1324/
+    # that supports single MoE layer independent of a transformer.
+    if tp_mesh is not None:
+        moe_layer_plan = {
+            # input / output sharding on the seqlen dim
+            # all-gather for input, reduce-scatter for output
+            "moe": PrepareModuleInputOutput(
+                input_layouts=(Shard(1),),
+                desired_input_layouts=(Replicate(),),
+                use_local_input=True,
+                output_layouts=(Partial(),),
+                desired_output_layouts=(Shard(1),),
+            ),
+            # replicate computation for the router
+            "moe.router.gate": NoParallel(),
+            # input Replicate, output Partial
+            "moe.shared_expert": TensorParallel(),
+        }
+        parallelize_module(
+            module=model,
+            device_mesh=tp_mesh,
+            parallelize_plan=moe_layer_plan,
+        )
+
+    # if ep_mesh is not None:
+    experts_mesh, experts_plan = None, None
+    if ep_mesh is None:
+        experts_mesh = tp_mesh
+        # input Replicate, output Partial
+        experts_plan = TensorParallel()
+    elif tp_mesh is None:
+        experts_mesh = ep_mesh
+        # input / output sharding on the batch / tokens dim
+        experts_plan = ExpertParallel()
+    else:
+        experts_mesh = ep_tp_mesh
+        experts_plan = ExpertTensorParallel(tp_mesh=tp_mesh, ep_mesh=ep_mesh)
+
+    parallelize_module(
+        module=model.experts,
+        device_mesh=experts_mesh,
+        parallelize_plan=experts_plan,
+    )

test/prototype/moe_training/test_tp.sh

@@ -1 +1 @@
-torchrun --nproc_per_node=2 -m pytest test/prototype/moe_training/test_tp.py
+torchrun --nproc_per_node=2 --local-ranks-filter=0 -m pytest test/prototype/moe_training/test_tp.py -s

test/prototype/moe_training/test_training.py

@@ -13,9 +13,10 @@
 
 from torchao.float8.float8_utils import compute_error
 from torchao.prototype.moe_training.conversion_utils import MoETrainingConfig
-from torchao.prototype.moe_training.tensor import ScaledGroupedMMTensor
 from torchao.quantization.quant_api import quantize_
 
+from .testing_utils import _validate_model_conversion
+
 # this test requires torchtitan
 try:
     from torchtitan.experiments.llama4.model.args import TransformerModelArgs
@@ -108,33 +109,3 @@ def moe_module_filter_fn(mod: nn.Module, cur_fqn: str) -> bool:
         assert param_grad_sqnr.item() >= 25.0, (
             f"SQNR must be >= 25.0, got {param_grad_sqnr.item()}."
         )
-
-
-def _validate_model_conversion(
-    root_module: nn.Module,
-    target_fqns: list[str],
-):
-    def _recursive_validate(
-        module: nn.Module,
-        cur_fqn: str,
-    ):
-        is_allowed_module = cur_fqn in target_fqns
-
-        # check current module params
-        for param_name, param in module.named_parameters(recurse=False):
-            is_converted_type = isinstance(param, ScaledGroupedMMTensor)
-            if is_converted_type:
-                assert is_allowed_module, (
-                    f"Module {cur_fqn} is not in target_fqns, but has converted param {param_name}."
-                )
-            if not is_allowed_module:
-                assert not is_converted_type, (
-                    f"Module {cur_fqn} is not in target_fqns, but has converted param {param_name}."
-                )
-
-        # recursively check child modules
-        for child_name, child_module in module.named_children():
-            child_fqn = f"{cur_fqn}.{child_name}" if cur_fqn else child_name
-            _recursive_validate(child_module, child_fqn)
-
-    _recursive_validate(root_module, "")

test/prototype/moe_training/testing_utils.py

@@ -0,0 +1,33 @@
+from torch import nn
+
+from torchao.prototype.moe_training.tensor import ScaledGroupedMMTensor
+
+
+def _validate_model_conversion(
+    root_module: nn.Module,
+    target_fqns: list[str],
+):
+    def _recursive_validate(
+        module: nn.Module,
+        cur_fqn: str,
+    ):
+        is_allowed_module = any([target_fqn in cur_fqn for target_fqn in target_fqns])
+
+        # check current module params
+        for param_name, param in module.named_parameters(recurse=False):
+            is_converted_type = isinstance(param, ScaledGroupedMMTensor)
+            if is_converted_type:
+                assert is_allowed_module, (
+                    f"Module {cur_fqn} is not in target_fqns, but has converted param {param_name}."
+                )
+            if not is_allowed_module:
+                assert not is_converted_type, (
+                    f"Module {cur_fqn} is not in target_fqns, but has converted param {param_name}."
+                )
+
+        # recursively check child modules
+        for child_name, child_module in module.named_children():
+            child_fqn = f"{cur_fqn}.{child_name}" if cur_fqn else child_name
+            _recursive_validate(child_module, child_fqn)
+
+    _recursive_validate(root_module, "")