Merge pull request #90 from xptree/multi_input

MoE with multiple inputs and multiple outputs

fmoe/layers.py

 r"""
 FMoE core layer
 """
+import tree
 import torch
 import torch.nn as nn
 
@@ -10,7 +11,6 @@ from .functions import AllGather, Slice
 from .gates import NaiveGate
 
 
-
 def mark_module_parallel_comm(module, comm):
     r"""
     Mark all parameters in `module` as doing data parallel in `comm`, where
@@ -42,22 +42,37 @@ def _fmoe_general_global_forward(inp, gate, expert_fn, num_expert, world_size):
     topk = 1
     if len(gate.shape) == 2:
         topk = gate.shape[1]
-    x = MOEScatter.apply(
-        inp, pos // topk,
-        local_expert_count, global_expert_count, fwd_batch_size, world_size
+
+    def scatter_func(tensor):
+        return MOEScatter.apply(
+            tensor,
+            pos // topk,
+            local_expert_count,
+            global_expert_count,
+            fwd_batch_size,
+            world_size,
         )
+
+    x = tree.map_structure(scatter_func, inp)
+
     x = expert_fn(x, fwd_expert_count)
 
-    out_batch_size = inp.shape[0]
+    out_batch_size = tree.flatten(inp)[0].shape[0]
     if len(gate.shape) == 2:
         out_batch_size *= gate.shape[1]
 
-    x = MOEGather.apply(
-        x, pos,
-        local_expert_count, global_expert_count,
-        out_batch_size, world_size
+    def gather_func(tensor):
+        return MOEGather.apply(
+            tensor,
+            pos,
+            local_expert_count,
+            global_expert_count,
+            out_batch_size,
+            world_size,
         )
-    return x
+
+    outp = tree.map_structure(gather_func, x)
+    return outp
 
 
 class FMoE(nn.Module):
@@ -101,7 +116,7 @@ class FMoE(nn.Module):
 
         self.slice_group = slice_group
         if mp_group is not None:
-            print('[Warning] mp_group is being deprecated')
+            print("[Warning] mp_group is being deprecated")
             self.slice_group = mp_group
         if self.slice_group is None:
             self.slice_size = 1
@@ -116,8 +131,7 @@ class FMoE(nn.Module):
             self.experts_fused = False
             self.num_expert = num_expert = len(expert)
         elif expert is not None:
-            self.experts = nn.ModuleList([expert(d_model)
-                for _ in range(num_expert)])
+            self.experts = nn.ModuleList([expert(d_model) for _ in range(num_expert)])
             self.experts_fused = False
         else:
             self.experts_fused = True
@@ -159,52 +173,109 @@ class FMoE(nn.Module):
                 mark_module_parallel_comm(self.experts, comm)
         mark_module_parallel_comm(self.gate, "gate")
 
-    def forward(self, inp):
+    def forward(self, moe_inp):
         r"""
         The FMoE module first computes gate output, and then conduct MoE forward
         according to the gate.  The score of the selected gate given by the
         expert is multiplied to the experts' output tensors as a weight.
         """
+
+        moe_inp_batch_size = tree.flatten(
+            tree.map_structure(lambda tensor: tensor.shape[0], moe_inp)
+        )
+        assert all(
+            [batch_size == moe_inp_batch_size[0] for batch_size in moe_inp_batch_size]
+        ), "MoE inputs must have the same batch size"
+
         if self.world_size > 1:
-            ensure_comm(inp, self.moe_group)
+
+            def ensure_comm_func(tensor):
+                ensure_comm(tensor, self.moe_group)
+
+            tree.map_structure(ensure_comm_func, moe_inp)
         if self.slice_size > 1:
-            inp = Slice.apply(inp, self.slice_rank,
-                    self.slice_size, self.slice_group)
 
-        gate_top_k_idx, gate_score = self.gate(inp)
+            def slice_func(tensor):
+                return Slice.apply(
+                    tensor, self.slice_rank, self.slice_size, self.slice_group
+                )
+
+            moe_inp = tree.map_structure(slice_func, moe_inp)
+
+        gate_top_k_idx, gate_score = self.gate(moe_inp)
 
         if self.gate_hook is not None:
             self.gate_hook(gate_top_k_idx, gate_score, None)
 
         # delete masked tensors
         if self.mask is not None and self.mask_dict is not None:
-            mask = self.mask.view(-1)
+            # TODO: to fix
+            def delete_mask_func(tensor):
                 # to: (BxL') x d_model
-            inp = inp[mask == 0, :]
+                tensor = tensor[mask == 0, :]
+                return tensor
+
+            mask = self.mask.view(-1)
+            moe_inp = tree.map_structure(delete_mask_func, moe_inp)
             gate_top_k_idx = gate_top_k_idx[mask == 0, :]
 
         fwd = _fmoe_general_global_forward(
-            inp, gate_top_k_idx,
-            self.expert_fn, self.num_expert, self.world_size
+            moe_inp, gate_top_k_idx, self.expert_fn, self.num_expert, self.world_size
         )
 
         # recover deleted tensors
         if self.mask is not None and self.mask_dict is not None:
-            # to: (BxL') x top_k x d_model
-            fwd = fwd.view(-1, self.top_k, self.d_model)
+
+            def recover_func(tensor):
+                # to: (BxL') x top_k x dim
+                dim = tensor.shape[-1]
+                tensor = tensor.view(-1, self.top_k, dim)
                 # to: (BxL) x top_k x d_model
-            x = torch.zeros(mask.shape[0], self.top_k, self.d_model, device=fwd.device, dtype=fwd.dtype)
+                x = torch.zeros(
+                    mask.shape[0],
+                    self.top_k,
+                    dim,
+                    device=tensor.device,
+                    dtype=tensor.dtype,
+                )
                 # recover
-            x[mask == 0] = fwd
+                x[mask == 0] = tensor
                 for k, v in self.mask_dict.items():
                     x[mask == k] = v
+                return x
+
+            moe_outp = tree.map_structure(recover_func, fwd)
         else:
-            x = fwd.view(-1, self.top_k, self.d_model)
 
-        gate_score = gate_score.view(x.shape[0], 1, self.top_k)
-        x = torch.bmm(gate_score, x).reshape(-1, self.d_model)
+            def view_func(tensor):
+                dim = tensor.shape[-1]
+                tensor = tensor.view(-1, self.top_k, dim)
+                return tensor
+
+            moe_outp = tree.map_structure(view_func, fwd)
+
+        gate_score = gate_score.view(-1, 1, self.top_k)
+
+        def bmm_func(tensor):
+            dim = tensor.shape[-1]
+            tensor = torch.bmm(gate_score, tensor).reshape(-1, dim)
+            return tensor
+
+        moe_outp = tree.map_structure(bmm_func, moe_outp)
 
         if self.slice_size > 1:
-            x = AllGather.apply(x, self.slice_rank,
-                    self.slice_size, self.slice_group)
-        return x
+
+            def all_gather_func(tensor):
+                return AllGather.apply(
+                    tensor, self.slice_rank, self.slice_size, self.slice_group
+                )
+
+            moe_outp = tree.map_structure(all_gather_func, moe_outp)
+
+        moe_outp_batch_size = tree.flatten(
+            tree.map_structure(lambda tensor: tensor.shape[0], moe_outp)
+        )
+        assert all(
+            [batch_size == moe_outp_batch_size[0] for batch_size in moe_outp_batch_size]
+        ), "MoE outputs must have the same batch size"
+        return moe_outp

requirements.txt

 torch
 numpy
 ninja
+dm-tree

tests/test_mimo.py

+import sys
+
+import pytest
+import torch
+import torch.nn as nn
+import numpy as np
+
+from fmoe.gates import NaiveGate
+from fmoe.layers import FMoE
+from fmoe.linear import FMoELinear
+from fmoe.megatron.layers import _megatron_init_method
+
+
+def _assert_numerical(names, moe_out_list, raw_out_list, rank, precision=1e-3):
+    for name, mo, ro in zip(names, moe_out_list, raw_out_list):
+        err = (mo - ro).abs().max()
+        print("Rank {} {} abs err {}".format(rank, name, err))
+        if err > precision:
+            sys.stderr.write(f"=========== {name} moe out ==============\n")
+            sys.stderr.write("{}\n".format(mo))
+            sys.stderr.write(f"=========== {name} raw out ==============\n")
+            sys.stderr.write("{}\n".format(ro))
+            sys.stderr.write(f"=========== {name} diff ==============\n")
+            sys.stderr.write("{}\n{}\n".format((mo - ro).abs(), err))
+            assert False
+
+
+class MyExpert(nn.Module):
+    r"""
+    An expert using 2 FMoELinear modules to speed up the computation of experts
+    within one worker.
+    """
+
+    def __init__(self, num_expert, d_model, d_hidden, activation, rank=0):
+        super().__init__()
+        self.htoh4 = FMoELinear(num_expert, d_model, d_hidden, bias=True, rank=rank)
+        self.h4toh = FMoELinear(num_expert, d_hidden, d_model, bias=True, rank=rank)
+        self.activation = activation
+
+    def forward(self, inp, fwd_expert_count):
+        r"""
+        First expand input to 4h (the hidden size is variable, but is called h4
+        for convenience). Then perform activation. Finally shirink back to h.
+        """
+        if type(inp) == dict:
+            x = inp["x"]
+            y = inp["y"]
+        elif type(inp) == list:
+            x = inp[0]
+            y = inp[1]
+        else:
+            raise NotImplementedError
+        x = self.htoh4(x, fwd_expert_count)
+        x = self.activation(x)
+        x = self.h4toh(x, fwd_expert_count)
+        y = self.htoh4(y, fwd_expert_count)
+        y = self.activation(y)
+        y = self.h4toh(y, fwd_expert_count)
+        if type(inp) == dict:
+            ret = {"x": x, "y": y}
+        elif type(inp) == list:
+            ret = [x, y]
+
+        return ret
+
+
+class MyGate(NaiveGate):
+    def __init__(self, d_model, num_expert, world_size, top_k=2):
+        super().__init__(d_model, num_expert, world_size, top_k)
+
+    def forward(self, inp, return_all_scores=False):
+        if type(inp) == dict:
+            x = inp["x"]
+        elif type(inp) == list:
+            x = inp[0]
+        else:
+            raise NotImplementedError
+        return super().forward(x, return_all_scores)
+
+
+class MyMoE(FMoE):
+    def __init__(
+        self, num_expert, d_model, d_hidden, world_size, mp_group, top_k, activation
+    ):
+        super().__init__(
+            num_expert=num_expert,
+            d_model=d_model,
+            gate=MyGate,
+            world_size=world_size,
+            mp_group=mp_group,
+            top_k=top_k,
+        )
+        self.experts = MyExpert(num_expert, d_model, d_hidden, activation)
+
+        rng = np.random.default_rng(1234)
+        _megatron_init_method(self.experts.htoh4, rng, 1.0)
+        _megatron_init_method(self.experts.h4toh, rng, 1.0)
+
+
+@pytest.mark.parametrize("num_expert", [4, 8])
+@pytest.mark.parametrize("top_k", [2, 3])
+@pytest.mark.parametrize("batch_size", [4])
+@pytest.mark.parametrize("d_model", [16])
+@pytest.mark.parametrize("d_hidden", [32])
+@pytest.mark.parametrize("rank", [0])
+@pytest.mark.parametrize("world_size", [1])
+@pytest.mark.parametrize("mp_group", [None])
+@pytest.mark.parametrize("dp_group", [None])
+@pytest.mark.parametrize("world_group", [None])
+@pytest.mark.parametrize(
+    "data_type", ["torch.FloatTensor", "torch.DoubleTensor", "torch.HalfTensor"]
+)
+@pytest.mark.parametrize("list_input", [False, True])
+def test_fmoe_mimo_linear(
+    num_expert,
+    top_k,
+    batch_size,
+    d_model,
+    d_hidden,
+    rank,
+    world_size,
+    mp_group,
+    dp_group,
+    world_group,
+    data_type,
+    list_input,
+    activation=torch.nn.functional.gelu,
+):
+
+    torch.manual_seed(42 + rank)
+    torch.cuda.manual_seed(42 + rank)
+
+    moe = MyMoE(
+        num_expert=num_expert,
+        d_model=d_model,
+        d_hidden=4 * d_model,
+        world_size=world_size,
+        mp_group=mp_group,
+        top_k=top_k,
+        activation=activation,
+    ).cuda()
+
+    x = torch.rand(batch_size, d_model).cuda()
+    inp = [x, x.clone()] if list_input else {"x": x, "y": x.clone()}
+    moe_out = moe(inp)
+
+    if list_input:
+        _assert_numerical(["x"], [moe_out[0]], [moe_out[1]], rank)
+    else:
+        _assert_numerical(["x"], [moe_out["x"]], [moe_out["y"]], rank)
+
+
+if __name__ == "__main__":
+    test_fmoe_mimo_linear(
+        batch_size=2,
+        num_expert=2,
+        d_model=2,
+        top_k=2,
+        d_hidden=16,
+        rank=0,
+        world_size=1,
+        mp_group=None,
+        dp_group=None,
+        world_group=None,
+        data_type=torch.float32,
+    )