From b9fb74f3bc6327062a747b7894d54d7b53a3a310 Mon Sep 17 00:00:00 2001
From: Xinyuan Tong <115166877+JustinTong0323@users.noreply.github.com>
Date: Fri, 24 Oct 2025 02:02:44 -0700
Subject: [PATCH] fix: bench_serving ITL calculation when using spec-decoding
 (#12064)

---
 python/sglang/bench_serving.py | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/python/sglang/bench_serving.py b/python/sglang/bench_serving.py
index 410af18f9..0a5550ff2 100644
--- a/python/sglang/bench_serving.py
+++ b/python/sglang/bench_serving.py
@@ -1626,6 +1626,7 @@ def calculate_metrics(
     dur_s: float,
     tokenizer: PreTrainedTokenizerBase,
     backend: str,
+    accept_length: Optional[float] = None,
 ) -> Tuple[BenchmarkMetrics, List[int]]:
     output_lens: List[int] = []
     retokenized_output_lens: List[int] = []
@@ -1650,7 +1651,14 @@ def calculate_metrics(
             total_input_vision += input_requests[i].vision_prompt_len
             if output_len > 1:
                 tpots.append((outputs[i].latency - outputs[i].ttft) / (output_len - 1))
-            itls += outputs[i].itl
+            if (
+                accept_length
+                and accept_length > 0
+                and backend in ("sglang-oai", "sglang-oai-chat")
+            ):
+                itls += [v / accept_length for v in outputs[i].itl]
+            else:
+                itls += outputs[i].itl
             ttfts.append(outputs[i].ttft)
 
             e2e_latencies.append(outputs[i].latency)
@@ -1929,6 +1937,7 @@ async def benchmark(
         dur_s=benchmark_duration,
         tokenizer=tokenizer,
         backend=backend,
+        accept_length=accept_length,
     )
 
     print("\n{s:{c}^{n}}".format(s=" Serving Benchmark Result ", n=50, c="="))