[torch.compile] add logging for compilation time (#10941)

Signed-off-by: youkaichao <youkaichao@gmail.com>
Co-authored-by: Woosuk Kwon <woosuk.kwon@berkeley.edu>

vllm/engine/llm_engine.py

@@ -473,6 +473,7 @@ class LLMEngine:
         The workers will determine the number of blocks in both the GPU cache
         and the swap CPU cache.
         """
+        start = time.time()
         num_gpu_blocks, num_cpu_blocks = (
             self.model_executor.determine_num_available_blocks())
 
@@ -488,6 +489,9 @@ class LLMEngine:
         self.cache_config.num_cpu_blocks = num_cpu_blocks
 
         self.model_executor.initialize_cache(num_gpu_blocks, num_cpu_blocks)
+        elapsed = time.time() - start
+        logger.info(("init engine (profile, create kv cache, "
+                     "warmup model) took %.2f seconds"), elapsed)
 
     @classmethod
     def _get_executor_cls(cls,