From 7fda3caea41e15cd1f7f1346b825f113e5b27b77 Mon Sep 17 00:00:00 2001
From: Michael <13900043+michaelzhang-ai@users.noreply.github.com>
Date: Wed, 20 May 2026 14:01:13 +0800
Subject: [PATCH] [AMD] test(sgl-kernel): seed RNG on ROCm in
 test_moe_topk_sigmoid to fix tie-break flake (#25356)

---
 sgl-kernel/tests/test_moe_topk_sigmoid.py | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/sgl-kernel/tests/test_moe_topk_sigmoid.py b/sgl-kernel/tests/test_moe_topk_sigmoid.py
index 1f9beb07a..e9a9240ee 100644
--- a/sgl-kernel/tests/test_moe_topk_sigmoid.py
+++ b/sgl-kernel/tests/test_moe_topk_sigmoid.py
@@ -5,6 +5,19 @@ import pytest
 import torch
 from sgl_kernel import topk_sigmoid
 
+_IS_HIP = torch.version.hip is not None
+
+
+@pytest.fixture(autouse=True)
+def _deterministic_seed():
+    # AMD/ROCm only: pin RNG so torch.randn produces identical gating scores
+    # across runs. atol=0 indices comparison is otherwise tripped by near-tied
+    # sigmoid scores where hipCUB's tie-break inside torch.topk disagrees with
+    # sgl_kernel.topk_sigmoid. Not observed on CUDA, so leave CUDA behavior
+    # unchanged.
+    if _IS_HIP:
+        torch.manual_seed(0)
+
 
 @pytest.mark.parametrize(
     "num_tokens, num_experts, topk",