[NPU] Avoid device synchronization in Ascend sampling (#39404)

test/registered/unit/sampling/test_sampling_batch_info.py

@@ -492,18 +492,21 @@ class TestMergeBatch(CustomTestCase):
             need_top_p_sampling=False,
             need_top_k_sampling=False,
             need_min_p_sampling=False,
+            npu_top_k_top_p_eligible=True,
         )
         info2 = _make_info(
             is_all_greedy=False,
             need_top_p_sampling=True,
             need_top_k_sampling=True,
             need_min_p_sampling=True,
+            npu_top_k_top_p_eligible=False,
         )
         info1.merge_batch(info2)
         self.assertFalse(info1.is_all_greedy)  # AND semantics
         self.assertTrue(info1.need_top_p_sampling)  # OR semantics
         self.assertTrue(info1.need_top_k_sampling)  # OR semantics
         self.assertTrue(info1.need_min_p_sampling)  # OR semantics
+        self.assertFalse(info1.npu_top_k_top_p_eligible)  # AND semantics
 
     def test_merge_with_logit_bias(self):
         """Test that merge pads missing logit_bias with zeros before concatenation."""
@@ -675,6 +678,22 @@ class TestFromScheduleBatch(CustomTestCase):
         self.assertTrue(info.need_min_p_sampling)  # 0.1 > 0
         self.assertFalse(info.is_all_greedy)  # top_k=50 > 1
 
+    def test_npu_top_k_top_p_eligibility_uses_request_params(self):
+        cases = (
+            ((1, 1024), True),
+            ((1, 1025), False),
+            ((4, TOP_K_ALL), False),
+        )
+        for top_ks, expected in cases:
+            with self.subTest(top_ks=top_ks):
+                batch = MagicMock()
+                batch.reqs = [self._make_req(top_k=top_k) for top_k in top_ks]
+                batch.device = DEVICE
+
+                info = SamplingBatchInfo.from_schedule_batch(batch, VOCAB_SIZE)
+
+                self.assertEqual(info.npu_top_k_top_p_eligible, expected)
+
     def test_no_logit_bias_when_all_none(self):
         """Test that logit_bias stays None when no request has logit_bias set."""