[platforms] refactor cpu code (#10402)

Signed-off-by: youkaichao <youkaichao@gmail.com>

vllm/platforms/cpu.py

@@ -1,8 +1,19 @@
+from typing import TYPE_CHECKING
+
 import psutil
 import torch
 
+from vllm.logger import init_logger
+
 from .interface import Platform, PlatformEnum
 
+if TYPE_CHECKING:
+    from vllm.config import VllmConfig
+else:
+    VllmConfig = None
+
+logger = init_logger(__name__)
+
 
 class CpuPlatform(Platform):
     _enum = PlatformEnum.CPU
@@ -18,3 +29,52 @@ class CpuPlatform(Platform):
     @classmethod
     def inference_mode(cls):
         return torch.no_grad()
+
+    @classmethod
+    def check_and_update_config(cls, vllm_config: VllmConfig) -> None:
+        import vllm.envs as envs
+        from vllm.utils import GiB_bytes
+        model_config = vllm_config.model_config
+        # Reminder: Please update docs/source/serving/compatibility_matrix.rst
+        # If the feature combo become valid
+        if not model_config.enforce_eager:
+            logger.warning(
+                "CUDA graph is not supported on CPU, fallback to the eager "
+                "mode.")
+            model_config.enforce_eager = True
+
+        cache_config = vllm_config.cache_config
+
+        if cache_config.enable_prefix_caching:
+            logger.warning(
+                "Prefix caching is not supported on CPU, disable it.")
+            cache_config.enable_prefix_caching = False
+
+        kv_cache_space = envs.VLLM_CPU_KVCACHE_SPACE
+
+        if kv_cache_space >= 0:
+            if kv_cache_space == 0:
+                cache_config.cpu_kvcache_space_bytes = 4 * GiB_bytes  # type: ignore
+                logger.warning(
+                    "Environment variable VLLM_CPU_KVCACHE_SPACE (GB) "
+                    "for CPU backend is not set, using 4 by default.")
+            else:
+                cache_config.cpu_kvcache_space_bytes = kv_cache_space * GiB_bytes  # type: ignore # noqa
+        else:
+            raise RuntimeError(
+                "Invalid environment variable VLLM_CPU_KVCACHE_SPACE"
+                f" {kv_cache_space}, expect a positive integer value.")
+
+        scheduler_config = vllm_config.scheduler_config
+        if scheduler_config.chunked_prefill_enabled:
+            logger.warning(
+                "Chunked prefill is not supported on CPU, disable it.")
+            scheduler_config.chunked_prefill_enabled = False
+
+        parallel_config = vllm_config.parallel_config
+        if (parallel_config.distributed_executor_backend is not None
+                and parallel_config.distributed_executor_backend != "mp"):
+            logger.warning(("%s is not supported on CPU, fallback to mp "
+                            "distributed executor backend."),
+                           parallel_config.distributed_executor_backend)
+            parallel_config.distributed_executor_backend = "mp"