Update benchmark_serving.py (#5861)

benchmarks/benchmark_serving.py

@@ -491,8 +491,14 @@ async def benchmark(
         # 多ip按DP均分并发
         assert max_concurrency, "multi-IP 模式必须指定 max_concurrency"
         n_ip = len(ip_list)
-        concurrency_per_ip = max_concurrency // n_ip
-        concurrency_remainder = max_concurrency % n_ip
+        if max_concurrency < n_ip:
+            print(
+                f"[WARN] max_concurrency({max_concurrency}) < IP 数({n_ip})，"
+                f"已自动兜底为每个 IP 1 并发，"
+                f"实际总并发将变为 {n_ip}"
+            )
+        concurrency_per_ip = max(1, max_concurrency // n_ip)
+        concurrency_remainder = max(0, max_concurrency - concurrency_per_ip * n_ip)
 
         # 分配请求
         req_per_ip = len(input_requests) // n_ip