[XPU] Remove redundant xpu graph backend and make xpu graph opt-in by default (#29911)

docs_new/docs/hardware-platforms/xpu.mdx

@@ -147,9 +147,18 @@ SGLang enables XPU graph capture to reduce per-step kernel-launch overhead.
 
 | Phase | Backend | Mechanism | Default |
 |---|---|---|---|
-| Decode | `full` | One `torch.xpu.XPUGraph` per batch size, captured on startup | **On** |
+| Decode | `full` | One `torch.xpu.XPUGraph` per batch size, captured on startup | **Off** (opt-in) |
 | Prefill | `tc_piecewise` | `torch.compile` + XPU graph, one graph segment per token-length bucket | **Off** (opt-in) |
 
+### Enable Decode Graph
+
+Decode graph capture is **opt-in** on XPU. Enable it explicitly:
+
+```bash
+python -m sglang.launch_server --model-path <MODEL> --device xpu \
+    --cuda-graph-backend-decode full
+```
+
 ### Enable Prefill Graph
 
 Prefill graph capture is **opt-in** on XPU and requires `torch.compile`
@@ -195,10 +204,10 @@ python -m sglang.launch_server --model-path <MODEL> --device xpu \
 
 ### Disable XPU Graph
 
-To opt out of one or both phases:
+Both phases are disabled by default. To explicitly disable them anyway:
 
 ```bash
-# Disable decode graph
+# Disable decode graph (already off by default; explicit form)
 python -m sglang.launch_server --model-path <MODEL> --device xpu \
     --cuda-graph-backend-decode=disabled
 
@@ -236,7 +245,7 @@ python -m sglang.launch_server \
 
 | Argument | XPU allowed values | Default | Description |
 |---|---|---|---|
-| `--cuda-graph-backend-decode` | `full`, `disabled` | `full` | Backend for the decode phase. Only `full` is supported on XPU. |
+| `--cuda-graph-backend-decode` | `full`, `disabled` | `disabled` | Backend for the decode phase. Only `full` is supported on XPU. Set to `full` to enable. |
 | `--cuda-graph-backend-prefill` | `tc_piecewise`, `disabled` | `disabled`* | Backend for the prefill phase. Must be set to `tc_piecewise` explicitly to enable. |
 | `--cuda-graph-tc-compiler` | `eager`, `inductor` | `eager` | Compiler for `tc_piecewise` prefill subgraphs. `inductor` produces more optimized code but has longer startup. |
 | `--cuda-graph-bs-prefill` | list of ints | auto | Explicit token-length buckets to capture for prefill. |

python/sglang/multimodal_gen/runtime/platforms/xpu.py

@@ -103,11 +103,22 @@ class XpuPlatform(Platform):
         if empty_cache:
             torch.xpu.empty_cache()
 
+        # Use mem_get_info() with a sanity cap to avoid KV-cache over-allocation
+        # on drivers that incorrectly return total memory as free memory.
+        # Consistent with the fallback: free = max(0, total - allocated).
+        try:
+            free_gpu_memory, total_gpu_memory = torch.xpu.mem_get_info(device_id)
+            used_memory = float(torch.xpu.memory_allocated(device_id))
+            free_gpu_memory = min(
+                float(free_gpu_memory),
+                max(0.0, float(total_gpu_memory) - used_memory),
+            )
+        except Exception:
+            # Fallback for devices/drivers that do not support querying free memory
             used_memory = float(torch.xpu.memory_allocated(device_id))
             total_gpu_memory = float(
                 torch.xpu.get_device_properties(device_id).total_memory
             )
-
             free_gpu_memory = max(0.0, total_gpu_memory - used_memory)
 
         if distributed:

python/sglang/srt/hardware_backend/xpu/graph_runner/xpu_graph_runner.py

@@ -22,7 +22,6 @@ import torch
 from torch.profiler import ProfilerActivity, profile
 
 from sglang.srt.model_executor.runner import DecodeCudaGraphRunner
-from sglang.srt.speculative.spec_info import SpeculativeAlgorithm
 from sglang.srt.utils import register_xpu_device_properties_for_dynamo
 
 logger = logging.getLogger(__name__)
@@ -144,9 +143,6 @@ class XPUGraphRunner(DecodeCudaGraphRunner):
         assert (
             not self.require_gathered_buffer
         ), "XPUGraphRunner does not support gathered buffer yet."
-        assert (
-            model_runner.spec_algorithm == SpeculativeAlgorithm.NONE
-        ), "XPUGraphRunner does not support speculative inference yet."
 
     def _init_profile_context_and_memory_record(self):
         profile_context = profile(

python/sglang/srt/hardware_backend/xpu/xpu_cudagraph_backend.py

@@ -1,106 +0,0 @@
-# Copyright 2023-2026 SGLang Team
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-# ==============================================================================
-"""XPUCudaGraphBackend — Intel XPU full-graph capture (torch.xpu.XPUGraph)."""
-
-from __future__ import annotations
-
-from contextlib import contextmanager
-from typing import TYPE_CHECKING, Any, Callable, Dict, Optional
-
-import torch
-
-from sglang.srt.model_executor.runner_backend.base_cuda_graph_backend import (
-    BaseCudaGraphBackend,
-)
-
-if TYPE_CHECKING:
-    from sglang.srt.model_executor.forward_batch_info import ForwardBatch
-    from sglang.srt.model_executor.runner.base_cuda_graph_runner import (
-        BaseCudaGraphRunner,
-    )
-
-
-class XPUCudaGraphBackend(BaseCudaGraphBackend):
-    """One torch.xpu.XPUGraph per shape; attention metadata is
-    captured inside the graph.
-    """
-
-    def __init__(
-        self,
-        cuda_graph_runner: BaseCudaGraphRunner,
-    ) -> None:
-        self._graphs: Dict[Any, torch.xpu.XPUGraph] = {}
-        self._outputs: Dict[Any, Any] = {}
-        self._pool = None
-        self._device_module = cuda_graph_runner.device_module
-        self._tp_group = cuda_graph_runner.model_runner.tp_group
-        self._capture_stream: Optional[torch.xpu.Stream] = None
-
-    @contextmanager
-    def capture_session(self, stream: torch.xpu.Stream):
-        if self._pool is None:
-            self._pool = self._device_module.graph_pool_handle()
-        self._capture_stream = stream
-        try:
-            yield
-        finally:
-            self._capture_stream = None
-
-    def capture_one(
-        self,
-        shape_key: Any,
-        forward_fn: Callable[[], Any],
-        dummies: Optional[Any] = None,
-        post_warmup_hook: Optional[Callable[[], None]] = None,
-    ) -> None:
-        # Two warmups so kernels are loaded and one-time setup is paid before capture.
-        # post_warmup_hook lets the attention backend reset state that warmup mutated.
-        for _ in range(2):
-            self._device_module.synchronize()
-            self._tp_group.barrier()
-            forward_fn()
-            if post_warmup_hook is not None:
-                post_warmup_hook()
-
-        graph = torch.xpu.XPUGraph()
-
-        # graph_ctx: Callable[..., AbstractContextManager]
-        graph_ctx = self._device_module.graph
-
-        with graph_ctx(graph, pool=self._pool, stream=self._capture_stream):
-            out = forward_fn()
-
-        self._graphs[shape_key] = graph
-        self._outputs[shape_key] = out
-
-    def can_run(self, forward_batch: ForwardBatch, shape_key: Any) -> bool:
-        return shape_key in self._graphs
-
-    @contextmanager
-    def replay_session(self):
-        yield
-
-    def replay(
-        self,
-        shape_key: Any,
-        static_forward_batch: ForwardBatch,
-        **kwargs,
-    ) -> Any:
-        self._graphs[shape_key].replay()
-        return self._outputs[shape_key]
-
-    def cleanup(self) -> None:
-        self._graphs.clear()
-        self._outputs.clear()
-        self._pool = None

python/sglang/srt/model_executor/runner_backend/utils.py

@@ -72,13 +72,6 @@ def resolve_decode_backend(
             cuda_graph_runner, enable_memory_saver=enable_memory_saver
         )
     elif model_runner.device == "xpu":
-        from sglang.srt.hardware_backend.xpu.xpu_cudagraph_backend import (
-            XPUCudaGraphBackend,
-        )
-
-        return XPUCudaGraphBackend(cuda_graph_runner)
-
-    if model_runner.device == "xpu":
         if backend_name not in (Backend.FULL, Backend.DISABLED):
             raise ValueError(
                 f"XPU only supports cuda_graph_config decode backend 'full', got '{backend_name}'"

python/sglang/srt/server_args.py

@@ -3054,6 +3054,22 @@ class ServerArgs:
 
     def _handle_xpu_backends(self):
         if self.device == "xpu":
+            # Decode graph is opt-in on XPU: unless the user explicitly set
+            # --cuda-graph-backend-decode (or --cuda-graph-config), keep it
+            # disabled so the default startup doesn't require graph capture.
+            if (Phase.DECODE, "backend") not in self._cuda_graph_config_locked:
+                self.cuda_graph_config.decode.backend = Backend.DISABLED
+            elif self.cuda_graph_config.decode.backend not in (
+                Backend.DISABLED,
+                Backend.FULL,
+            ):
+                logger.warning(
+                    "XPU platform only supports decode backend 'full'; "
+                    "disabling unsupported decode backend '%s'.",
+                    self.cuda_graph_config.decode.backend,
+                )
+                self.cuda_graph_config.decode.backend = Backend.DISABLED
+
             if self.cuda_graph_config.prefill.backend not in (
                 Backend.DISABLED,
                 Backend.TC_PIECEWISE,

python/sglang/srt/utils/common.py

@@ -621,9 +621,23 @@ def get_available_gpu_memory(
 
         if empty_cache:
             empty_device_cache(torch.xpu)
-        # Use mem_get_info() to reflect true OS-level free memory
-        # including graph pool reservations; avoids KV-cache over-allocation.
+        # Use mem_get_info() with a sanity cap to avoid KV-cache over-allocation
+        # on drivers that incorrectly return total memory as free memory.
+        # Consistent with the fallback: free = max(0, total - allocated).
+        try:
             free_gpu_memory, total_gpu_memory = torch.xpu.mem_get_info(gpu_id)
+            used_memory = float(torch.xpu.memory_allocated(gpu_id))
+            free_gpu_memory = min(
+                float(free_gpu_memory),
+                max(0.0, float(total_gpu_memory) - used_memory),
+            )
+        except Exception:
+            # Fallback for devices/drivers that do not support querying free memory
+            used_memory = float(torch.xpu.memory_allocated(gpu_id))
+            total_gpu_memory = float(
+                torch.xpu.get_device_properties(gpu_id).total_memory
+            )
+            free_gpu_memory = max(0.0, total_gpu_memory - used_memory)
 
     elif device == "hpu":
         num_gpus = torch.hpu.device_count()

test/registered/spec/eagle/test_spec_eagle_parity.py

@@ -42,6 +42,10 @@ class TestEagle3ParityXPU(SpecParityKit, _Eagle3ParityBase):
 
     disable_overlap = False
     attention_backend = "triton"
+    # Decode full-graph was active by default when this test was added
+    # (via XPUCudaGraphBackend). Opt in explicitly now that it is disabled
+    # by default so the coverage is preserved.
+    extra_args = ("--cuda-graph-config", '{"decode":{"backend":"full"}}')
 
 
 if __name__ == "__main__":

test/registered/xpu/test_deepseek_ocr.py

@@ -38,7 +38,6 @@ class TestDeepSeekOCR(CustomTestCase):
             "xpu",
             "--attention-backend",
             "intel_xpu",
-            "--disable-decode-cuda-graph",
         ]
         os.environ["SGLANG_USE_SGL_XPU"] = "1"
         cls.process = popen_launch_server(

test/registered/xpu/test_deepseek_ocr_triton.py

@@ -41,7 +41,6 @@ class TestDeepSeekOCRTriton(TestDeepSeekOCR):
             "xpu",
             "--attention-backend",
             "intel_xpu",
-            "--disable-decode-cuda-graph",
         ]
         os.environ["SGLANG_USE_SGL_XPU"] = "0"
         cls.process = popen_launch_server(

test/registered/xpu/test_encoder_attention_backend.py

@@ -39,7 +39,6 @@ class TestEncoderAttention(CustomTestCase):
             "xpu",
             "--mm-attention-backend",
             "xpu_attn",
-            "--disable-decode-cuda-graph",
         ]
         os.environ["SGLANG_USE_SGL_XPU"] = "1"
         cls.process = popen_launch_server(
@@ -128,7 +127,6 @@ class TestEncoderAttention_Triton(TestEncoderAttention):
             "xpu",
             "--mm-attention-backend",
             "triton_attn",
-            "--disable-decode-cuda-graph",
         ]
         os.environ["SGLANG_USE_SGL_XPU"] = "0"
         cls.process = popen_launch_server(

test/registered/xpu/test_gemma_4_e2b.py

@@ -53,7 +53,6 @@ XPU_SERVER_ARGS = [
     "intel_xpu",
     "--model-impl",
     "sglang",
-    "--disable-decode-cuda-graph",
 ]
 
 # Standard sglang e2e Q&A prompt (see test_openai_server.py::run_chat_completion).

test/registered/xpu/test_intel_xpu_backend.py

@@ -34,7 +34,6 @@ def intel_xpu_benchmark(
                 "1",
                 "--device",
                 "xpu",
-                "--disable-decode-cuda-graph",
             ]
             ci_args = ["--input", "64", "--output", "4"] if is_in_ci() else []
             full_args = common_args + ci_args + (extra_args or [])

test/registered/xpu/test_triton_attention_backend.py

@@ -31,7 +31,6 @@ def triton_attention_benchmark(extra_args=None, mem_fraction_static="0.84"):
                 "2050",
                 "--attention-backend",
                 "triton",
-                "--disable-decode-cuda-graph",
             ]
             full_args = common_args + (extra_args or [])
 

test/registered/xpu/test_xpu_basic.py

@@ -33,7 +33,6 @@ class TestXPUBasic(CustomTestCase):
             "0.6",
             "--batch-size",
             "1",
-            "--disable-decode-cuda-graph",
         ]
         if is_in_ci():
             args += ["--input", "64", "--output", "4"]

test/registered/xpu/test_xpu_embedding.py

@@ -38,7 +38,6 @@ class TestXPUEmbedding(CustomTestCase):
                 "--is-embedding",
                 "--device",
                 "xpu",
-                "--disable-decode-cuda-graph",
             ],
         )
         cls.openai_url = cls.base_url + "/v1"

test/registered/xpu/test_xpu_serving_features.py

@@ -43,7 +43,7 @@ class TestXPUServingFeatures(CustomTestCase):
             cls.model,
             cls.base_url,
             timeout=DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
-            other_args=["--device", "xpu", "--disable-decode-cuda-graph"],
+            other_args=["--device", "xpu"],
         )
         cls.openai_url = cls.base_url + "/v1"