[gpt-oss] Add gpt-oss bf16 support

vllm/model_executor/layers/quantization/experts_int8.py

@@ -0,0 +1,196 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+from typing import Any, Callable, Optional
+
+import torch
+
+from vllm.distributed import get_tensor_model_parallel_rank, get_tp_group
+from vllm.model_executor.layers.fused_moe import FusedMoE, FusedMoEMethodBase
+from vllm.model_executor.layers.linear import (LinearBase,
+                                               UnquantizedLinearMethod)
+from vllm.model_executor.layers.quantization import QuantizationMethods
+from vllm.model_executor.layers.quantization.base_config import (
+    QuantizationConfig, QuantizeMethodBase)
+from vllm.model_executor.utils import set_weight_attrs
+
+
+class ExpertsInt8Config(QuantizationConfig):
+    """Config class for Int8 experts quantization."""
+
+    def __init__(self) -> None:
+        super().__init__()
+
+    @classmethod
+    def get_name(cls) -> QuantizationMethods:
+        return "experts_int8"
+
+    @classmethod
+    def get_supported_act_dtypes(cls) -> list[torch.dtype]:
+        return [torch.bfloat16, torch.half]
+
+    @classmethod
+    def get_min_capability(cls) -> int:
+        return 80
+
+    @classmethod
+    def get_config_filenames(cls) -> list[str]:
+        return []
+
+    @classmethod
+    def from_config(cls, config: dict[str, Any]) -> "ExpertsInt8Config":
+        return cls()
+
+    def get_quant_method(self, layer: torch.nn.Module,
+                         prefix: str) -> Optional["QuantizeMethodBase"]:
+        if isinstance(layer, LinearBase):
+            return UnquantizedLinearMethod()
+        elif isinstance(layer, FusedMoE):
+            return ExpertsInt8MoEMethod(self)
+        return None
+
+
+class ExpertsInt8MoEMethod(FusedMoEMethodBase):
+
+    def __init__(self, quant_config: ExpertsInt8Config):
+        self.quant_config = quant_config
+
+    def create_weights(self, layer: torch.nn.Module, num_experts: int,
+                       hidden_size: int, intermediate_size_per_partition: int,
+                       params_dtype: torch.dtype, **extra_weight_attrs):
+
+        int8_dtype = torch.int8
+
+        assert 'weight_loader' in extra_weight_attrs
+        weight_loader = extra_weight_attrs['weight_loader']
+        wrapped_weight_loader = ExpertsInt8MoEMethod.quantizing_weight_loader(
+            layer, weight_loader)
+        extra_weight_attrs['weight_loader'] = wrapped_weight_loader
+
+        # Fused gate_up_proj (column parallel)
+        w13_weight = torch.nn.Parameter(torch.empty(
+            num_experts,
+            2 * intermediate_size_per_partition,
+            hidden_size,
+            dtype=int8_dtype),
+                                        requires_grad=False)
+        layer.register_parameter("w13_weight", w13_weight)
+        set_weight_attrs(w13_weight, extra_weight_attrs)
+
+        # down_proj (row parallel)
+        w2_weight = torch.nn.Parameter(torch.empty(
+            num_experts,
+            hidden_size,
+            intermediate_size_per_partition,
+            dtype=int8_dtype),
+                                       requires_grad=False)
+        layer.register_parameter("w2_weight", w2_weight)
+        set_weight_attrs(w2_weight, extra_weight_attrs)
+
+        w13_scale = torch.nn.Parameter(torch.zeros(
+            num_experts,
+            2 * intermediate_size_per_partition,
+            dtype=torch.float32),
+                                       requires_grad=False)
+        layer.register_parameter("w13_scale", w13_scale)
+
+        w2_scale = torch.nn.Parameter(torch.zeros(num_experts,
+                                                  hidden_size,
+                                                  dtype=torch.float32),
+                                      requires_grad=False)
+        layer.register_parameter("w2_scale", w2_scale)
+
+    def apply(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        router_logits: torch.Tensor,
+        top_k: int,
+        renormalize: bool,
+        use_grouped_topk: bool = False,
+        topk_group: Optional[int] = None,
+        num_expert_group: Optional[int] = None,
+        global_num_experts: int = -1,
+        expert_map: Optional[torch.Tensor] = None,
+        custom_routing_function: Optional[Callable] = None,
+        scoring_func: str = "softmax",
+        e_score_correction_bias: Optional[torch.Tensor] = None,
+        apply_router_weight_on_input: bool = False,
+        activation: str = "silu",
+    ) -> torch.Tensor:
+        from vllm.model_executor.layers.fused_moe import fused_experts
+
+        topk_weights, topk_ids = FusedMoE.select_experts(
+            hidden_states=x,
+            router_logits=router_logits,
+            use_grouped_topk=use_grouped_topk,
+            top_k=top_k,
+            renormalize=renormalize,
+            topk_group=topk_group,
+            num_expert_group=num_expert_group,
+            custom_routing_function=custom_routing_function,
+            scoring_func=scoring_func,
+            e_score_correction_bias=e_score_correction_bias)
+
+        return fused_experts(
+            x,
+            layer.w13_weight,
+            layer.w2_weight,
+            topk_weights=topk_weights,
+            topk_ids=topk_ids,
+            inplace=True,
+            activation=activation,
+            use_int8_w8a16=True,
+            global_num_experts=global_num_experts,
+            apply_router_weight_on_input=apply_router_weight_on_input,
+            expert_map=expert_map,
+            w1_scale=layer.w13_scale,
+            w2_scale=layer.w2_scale)
+
+    @staticmethod
+    def quantizing_weight_loader(layer, weight_loader):
+
+        def quantize_and_call_weight_loader(param: torch.nn.Parameter,
+                                            loaded_weight: torch.Tensor,
+                                            weight_name: str, shard_id: int,
+                                            expert_id: int):
+            tp_rank = get_tensor_model_parallel_rank()
+            shard_size = layer.intermediate_size_per_partition
+            shard = slice(tp_rank * shard_size, (tp_rank + 1) * shard_size)
+            device = get_tp_group().device
+            loaded_weight = loaded_weight.to(device)
+            # w1, gate_proj case: Load into first shard of w13.
+            if shard_id == "w1":
+                scales = quantize_in_place_and_get_scales(
+                    loaded_weight[shard, :])
+                layer.w13_scale.data[expert_id, 0:shard_size].copy_(scales[:,
+                                                                           0])
+            # w3, up_proj case: Load into second shard of w13.
+            elif shard_id == "w3":
+                scales = quantize_in_place_and_get_scales(
+                    loaded_weight[shard, :])
+                layer.w13_scale.data[expert_id, shard_size:2 *
+                                     shard_size].copy_(scales[:, 0])
+            # w2, down_proj case: Load into only shard of w2.
+            elif shard_id == "w2":
+                scales = quantize_in_place_and_get_scales(loaded_weight[:,
+                                                                        shard])
+                layer.w2_scale.data[expert_id, :].copy_(scales[:, 0])
+            else:
+                raise ValueError(
+                    f"Shard id must be in [0,1,2] but got {shard_id}")
+            weight_loader(param, loaded_weight, weight_name, shard_id,
+                          expert_id)
+
+        return quantize_and_call_weight_loader
+
+
+def quantize_in_place_and_get_scales(weight: torch.Tensor) -> torch.Tensor:
+    vmax = torch.iinfo(torch.int8).max
+    scales = (torch.max(torch.abs(weight), dim=1, keepdim=True)[0] / vmax)
+
+    weight.div_(scales)
+    weight.round_()
+    weight.clamp_(-vmax, vmax)
+
+    return scales