add info log reminder zero overhead start

vllm/engine/llm_engine.py

@@ -1326,6 +1326,7 @@ class LLMEngine:
             self.sem_m2s.release()
     
     def thread_zero_overhead(self):        
+        logger.info('zero overhead thread start!')
         try:
             while True:
                 self.sem_m2s.acquire()