Print warnings/errors for large swap space (#123)

cacheflow/config.py

@@ -3,6 +3,11 @@ from typing import Optional
 import torch
 from transformers import AutoConfig, PretrainedConfig
 
+from cacheflow.logger import init_logger
+from cacheflow.utils import get_cpu_memory
+
+logger = init_logger(__name__)
+
 _GiB = 1 << 30
 
 
@@ -73,11 +78,37 @@ class CacheConfig:
         self.block_size = block_size
         self.gpu_memory_utilization = gpu_memory_utilization
         self.swap_space_bytes = swap_space * _GiB
+        self._verify_args()
 
         # Will be set after profiling.
         self.num_gpu_blocks = None
         self.num_cpu_blocks = None
 
+    def _verify_args(self) -> None:
+        if self.gpu_memory_utilization > 1.0:
+            raise ValueError(
+                "GPU memory utilization must be less than 1.0. Got "
+                f"{self.gpu_memory_utilization}.")
+
+    def verify_with_parallel_config(
+        self,
+        parallel_config: "ParallelConfig",
+    ) -> None:
+        total_cpu_memory = get_cpu_memory()
+        # FIXME(woosuk): Here, it is assumed that the GPUs in a tensor parallel
+        # group are in the same node. However, the GPUs may span multiple nodes.
+        num_gpus_per_node = parallel_config.tensor_parallel_size
+        cpu_memory_usage = self.swap_space_bytes * num_gpus_per_node
+
+        msg = (
+            f"{cpu_memory_usage / _GiB:.2f} GiB out of "
+            f"the {total_cpu_memory / _GiB:.2f} GiB total CPU memory is "
+            "allocated for the swap space.")
+        if cpu_memory_usage > 0.7 * total_cpu_memory:
+            raise ValueError("Too large swap space. " + msg)
+        elif cpu_memory_usage > 0.4 * total_cpu_memory:
+            logger.warn("Possibly too large swap space. " + msg)
+
 
 class ParallelConfig:
 

cacheflow/server/llm_server.py

@@ -84,6 +84,7 @@ class LLMServer:
 
     def _verify_args(self) -> None:
         self.model_config.verify_with_parallel_config(self.parallel_config)
+        self.cache_config.verify_with_parallel_config(self.parallel_config)
 
     def _init_cache(self) -> None:
         # Get the maximum number of blocks that can be allocated on GPU and CPU.

cacheflow/utils.py

@@ -24,8 +24,10 @@ class Counter:
 
 
 def get_gpu_memory(gpu: int = 0) -> int:
+    """Returns the total memory of the GPU in bytes."""
     return torch.cuda.get_device_properties(gpu).total_memory
 
 
 def get_cpu_memory() -> int:
+    """Returns the total CPU memory of the node in bytes."""
     return psutil.virtual_memory().total