[Hardware][CPU] Support MOE models on x86 CPU (vllm-project#11831)

Signed-off-by: jiang1.li <[email protected]>

docs/source/getting_started/installation/cpu-x86.md

@@ -5,7 +5,7 @@
 vLLM initially supports basic model inferencing and serving on x86 CPU platform, with data types FP32, FP16 and BF16. vLLM CPU backend supports the following vLLM features:
 
 - Tensor Parallel
-- Model Quantization (`INT8 W8A8, AWQ`)
+- Model Quantization (`INT8 W8A8, AWQ, GPTQ`)
 - Chunked-prefill
 - Prefix-caching
 - FP8-E5M2 KV-Caching (TODO)

tests/models/decoder_only/language/test_models.py

@@ -48,6 +48,10 @@
         ),
         pytest.param("stabilityai/stablelm-3b-4e1t"),  # stablelm
         pytest.param("bigcode/starcoder2-3b"),  # starcoder2
+        pytest.param(
+            "ehristoforu/Falcon3-MoE-2x7B-Insruct",  # mixtral
+            marks=[pytest.mark.cpu_model],
+        )
     ])
 @pytest.mark.parametrize("dtype", ["half"])
 @pytest.mark.parametrize("max_tokens", [32])

vllm/model_executor/layers/fused_moe/layer.py

@@ -13,6 +13,7 @@
     QuantizationConfig, QuantizeMethodBase)
 from vllm.model_executor.utils import set_weight_attrs
 from vllm.platforms import current_platform
+from vllm.platforms.interface import CpuArchEnum
 
 if current_platform.is_cuda_alike():
     from .fused_moe import fused_experts
@@ -83,6 +84,20 @@ def create_weights(self, layer: torch.nn.Module, num_experts: int,
         layer.register_parameter("w2_weight", w2_weight)
         set_weight_attrs(w2_weight, extra_weight_attrs)
 
+    def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
+        super().process_weights_after_loading(layer)
+
+        if current_platform.is_cpu():
+            if current_platform.get_cpu_architecture() == CpuArchEnum.X86:
+                import intel_extension_for_pytorch as ipex
+                layer.ipex_fusion = ipex.llm.modules.GatedMLPMOE(
+                    layer.w13_weight,
+                    layer.w2_weight,
+                    use_prepack=True,
+                )
+            else:
+                raise NotImplementedError("CPU MOE only supports x86 arch.")
+
     def apply(
         self,
         layer: torch.nn.Module,
@@ -142,9 +157,29 @@ def forward_cuda(
                              topk_ids=topk_ids,
                              inplace=True)
 
-    def forward_cpu(self, *args, **kwargs):
-        raise NotImplementedError(
-            "The CPU backend currently does not support MoE.")
+    def forward_cpu(
+        self,
+        layer: torch.nn.Module,
+        x: torch.Tensor,
+        use_grouped_topk: bool,
+        top_k: int,
+        router_logits: torch.Tensor,
+        renormalize: bool,
+        topk_group: Optional[int] = None,
+        num_expert_group: Optional[int] = None,
+        custom_routing_function: Optional[Callable] = None,
+        **kwargs,
+    ):
+        assert custom_routing_function is None
+        return layer.ipex_fusion(
+            x,
+            use_grouped_topk,
+            top_k,
+            router_logits,
+            renormalize,
+            topk_group,
+            num_expert_group,
+        )
 
     def forward_tpu(
         self,