[Frontend] CompilationConfig overhaul (#20283): deprecate use_inductor in favor of backend, simplify custom_ops (#26113)

Signed-off-by: morrison-turnansky <mturnans@redhat.com>
Signed-off-by: Morrison Turnansky <mturnans@redhat.com>
Signed-off-by: Luka Govedič <ProExpertProg@users.noreply.github.com>
Co-authored-by: Luka Govedič <ProExpertProg@users.noreply.github.com>
Co-authored-by: Jiangyun Zhu <riverclouds.zhu@qq.com>

tests/compile/piecewise/test_toy_llama.py

@@ -258,13 +258,13 @@ def tractable_computation(
 
 @torch.inference_mode
 def run_model(
-    llama_config, use_compile: bool, use_inductor: bool, split_attn: bool = False
+    llama_config, use_compile: bool, backend: str, split_attn: bool = False
 ) -> torch.Tensor:
     if use_compile:
         compilation_config = CompilationConfig(
             level=CompilationLevel.PIECEWISE,
             use_cudagraph=True,
-            use_inductor=use_inductor,
+            backend=backend,
             cudagraph_capture_sizes=[1, 2],
         )
         if split_attn:
@@ -338,8 +338,8 @@ def run_model(
             return output.cpu()
 
 
-@pytest.mark.parametrize("use_inductor", [True, False])
-def test_toy_llama(use_inductor: bool):
+@pytest.mark.parametrize("backend", ["inductor", "eager"])
+def test_toy_llama(backend: str):
     # compare output with and without piecewise compilation
 
     llama_config = LlamaConfig(
@@ -358,10 +358,10 @@ def test_toy_llama(use_inductor: bool):
         num_backend_compilations=0,
         num_cudagraph_captured=0,
     ):
-        outputs.append(run_model(llama_config, use_inductor=False, use_compile=False))
-    run_model(tractable_config, use_inductor=False, use_compile=False)
+        outputs.append(run_model(llama_config, backend="eager", use_compile=False))
+    run_model(tractable_config, backend="eager", use_compile=False)
 
-    if use_inductor:
+    if backend == "inductor":
         kwargs = {"num_inductor_compiles": 1, "num_eager_compiles": 0}
     else:
         kwargs = {"num_eager_compiles": 1, "num_inductor_compiles": 0}
@@ -377,10 +377,8 @@ def test_toy_llama(use_inductor: bool):
         num_cudagraph_captured=2,
         **kwargs,
     ):
-        outputs.append(
-            run_model(llama_config, use_inductor=use_inductor, use_compile=True)
-        )
-    run_model(tractable_config, use_inductor=use_inductor, use_compile=True)
+        outputs.append(run_model(llama_config, backend=backend, use_compile=True))
+    run_model(tractable_config, backend=backend, use_compile=True)
 
     with compilation_counter.expect(
         num_graphs_seen=1,  # one graph for the model
@@ -395,16 +393,9 @@ def test_toy_llama(use_inductor: bool):
         ),  # num_cudagraph_sizes * num_piecewise_capturable_graphs_seen
     ):
         outputs.append(
-            run_model(
-                llama_config,
-                use_inductor=use_inductor,
-                use_compile=True,
-                split_attn=True,
-            )
+            run_model(llama_config, backend=backend, use_compile=True, split_attn=True)
         )
-    run_model(
-        tractable_config, use_inductor=use_inductor, use_compile=True, split_attn=True
-    )
+    run_model(tractable_config, backend=backend, use_compile=True, split_attn=True)
 
     for i in range(1, len(outputs)):
         assert torch.allclose(outputs[0], outputs[i])

tests/model_executor/test_enabled_custom_ops.py

@@ -37,57 +37,59 @@ class Relu3(ReLUSquaredActivation):
 
 
 @pytest.mark.parametrize(
-    "env, torch_level, use_inductor, ops_enabled, default_on",
+    "env, torch_level, backend, ops_enabled, default_on",
     [
         # Default values based on compile level
         # - All by default (no Inductor compilation)
-        (None, 0, False, [True] * 4, True),
-        (None, 1, True, [True] * 4, True),
-        (None, 2, False, [True] * 4, True),
+        (None, 0, "eager", [True] * 4, True),
+        (None, 1, "eager", [True] * 4, True),
+        (None, 2, "eager", [True] * 4, True),
+        (None, 3, "eager", [True] * 4, True),
         # - None by default (with Inductor)
-        (None, 3, True, [False] * 4, False),
-        (None, 4, True, [False] * 4, False),
-        # - All by default (without Inductor)
-        (None, 3, False, [True] * 4, True),
-        (None, 4, False, [True] * 4, True),
+        (None, 0, "inductor", [True] * 4, True),
+        # - None by default (with Inductor)
+        (None, 1, "inductor", [False] * 4, False),
+        (None, 2, "inductor", [False] * 4, False),
+        (None, 3, "inductor", [False] * 4, False),
         # Explicitly enabling/disabling
         #
         # Default: all
         #
         # All but SiluAndMul
-        ("+rms_norm,-silu_and_mul", 0, True, [1, 0, 1, 1], True),
+        ("+rms_norm,-silu_and_mul", 0, "inductor", [1, 0, 1, 1], True),
         # Only ReLU3
-        ("none,-rms_norm,+relu3", 1, False, [0, 0, 0, 1], False),
+        ("none,-rms_norm,+relu3", 1, "eager", [0, 0, 0, 1], False),
         # All but SiluAndMul
-        ("all,-silu_and_mul", 2, True, [1, 0, 1, 1], True),
+        ("all,-silu_and_mul", 2, "inductor", [1, 0, 1, 1], True),
         # All but ReLU3 (even if ReLU2 is on)
-        ("-relu3,+relu2", 3, False, [1, 1, 1, 0], True),
+        ("-relu3,+relu2", 3, "eager", [1, 1, 1, 0], True),
         # RMSNorm and SiluAndMul
-        ("none,-relu3,+rms_norm,+silu_and_mul", 4, False, [1, 1, 0, 0], False),
+        ("none,-relu3,+rms_norm,+silu_and_mul", 3, "eager", [1, 1, 0, 0], False),
         # All but RMSNorm
-        ("-rms_norm", 3, False, [0, 1, 1, 1], True),
+        ("-rms_norm", 3, "eager", [0, 1, 1, 1], True),
         #
         # Default: none
         #
         # Only ReLU3
-        ("-silu_and_mul,+relu3", 3, True, [0, 0, 0, 1], False),
+        ("none,+relu3", 3, "inductor", [0, 0, 0, 1], False),
         # All but RMSNorm
-        ("all,-rms_norm", 4, True, [0, 1, 1, 1], True),
+        ("all,-rms_norm", 3, "inductor", [0, 1, 1, 1], True),
     ],
 )
 def test_enabled_ops(
     env: Optional[str],
     torch_level: int,
-    use_inductor: bool,
+    backend: str,
     ops_enabled: list[int],
     default_on: bool,
 ):
     custom_ops = env.split(",") if env else []
     vllm_config = VllmConfig(
         compilation_config=CompilationConfig(
-            use_inductor=bool(use_inductor), level=torch_level, custom_ops=custom_ops
+            backend=backend, level=torch_level, custom_ops=custom_ops
         )
     )
+    # breakpoint()
     with set_current_vllm_config(vllm_config):
         assert CustomOp.default_on() == default_on
 

vllm/compilation/backends.py

@@ -34,7 +34,7 @@ logger = init_logger(__name__)
 
 
 def make_compiler(compilation_config: CompilationConfig) -> CompilerInterface:
-    if compilation_config.use_inductor:
+    if compilation_config.backend == "inductor":
         # Use standalone compile only if requested, version is new enough,
         # and the symbol actually exists in this PyTorch build.
         if (
@@ -48,6 +48,10 @@ def make_compiler(compilation_config: CompilationConfig) -> CompilerInterface:
             logger.debug("Using InductorAdaptor")
             return InductorAdaptor()
     else:
+        assert compilation_config.backend == "eager", (
+            "Custom backends not supported with CompilationLevel.PIECEWISE"
+        )
+
         logger.debug("Using EagerAdaptor")
         return EagerAdaptor()
 

vllm/config/compilation.py

@@ -180,10 +180,11 @@ class CompilationConfig:
     """The directory to store the compiled graph, to accelerate Inductor
     compilation. By default, it will use model-related information to generate
     a cache directory."""
-    backend: str = ""
+    backend: str = "inductor"
     """The backend for compilation. It needs to be a string:
 
-    - "" (empty string): use the default backend.
+    - "" (empty string): use the default backend ("inductor" on CUDA-alike
+    platforms).
     - "eager"/"openxla"/...: use the specified backend registered in PyTorch.
     - "full.module.name": a qualified name which can be used to import the
 
@@ -192,7 +193,11 @@ class CompilationConfig:
     distributed setting. When the compilation level is 1 or 2, the backend is
     used for the compilation directly (it sees the whole graph). When the
     compilation level is 3, the backend is used for the piecewise compilation
-    (it sees a part of the graph)."""
+    (it sees a part of the graph). The backend can not be custom for compilation
+    level 3. Furthermore, compilation is only piecewise if splitting ops is set
+    accordingly and use_inductor_cudagraphs_partition is off. Note that the
+    default options for splitting ops are sufficient for piecewise compilation.
+    """
     custom_ops: list[str] = field(default_factory=list)
     """Fine-grained control over which custom ops to enable/disable. Use 'all'
     to enable all, 'none' to disable all. Also specify a list of custom op
@@ -210,8 +215,12 @@ class CompilationConfig:
     compilation."""
 
     # Inductor capture
-    use_inductor: bool = True
-    """Whether to use inductor compilation:
+    use_inductor: Optional[bool] = None
+    """
+    Whether to use inductor compilation.
+
+    This flag is deprecated and will be removed.
+    Please use the 'backend' option instead.
 
     - False: inductor compilation is not used. graph runs in eager
         (custom_ops enabled by default).
@@ -219,7 +228,11 @@ class CompilationConfig:
         One graph for symbolic shape and one graph per size in compile_sizes
         are compiled using configurations in inductor_compile_config.
 
-    This setting is ignored if level<PIECEWISE."""
+    This setting is ignored if level<PIECEWISE.
+
+    For future compatibility:
+    If use_inductor is True, backend="inductor" otherwise backend="eager".
+    """
     compile_sizes: Optional[list[Union[int, str]]] = None
     """Sizes to compile for inductor. In addition
     to integers, it also supports "cudagraph_capture_sizes" to
@@ -523,7 +536,43 @@ class CompilationConfig:
                     "(where 'op' is the registered op name)"
                 )
 
+        # Currently only eager and inductor backend are supported.
+        # for piecewise compilation. Custom backends are not suppported for
+        # piecewise compilation. Update when more backends are supported.
+        if self.level == CompilationLevel.PIECEWISE and self.backend not in [
+            "",
+            "eager",
+            "inductor",
+        ]:
+            raise ValueError(
+                f"Invalid backend for piecewise compilation: {self.backend}"
+            )
+
+        if self.use_inductor is not None:
+            logger.warning_once(
+                "The 'use_inductor' flag is deprecated and will be\
+                    removed in a future release."
+                "Please use the 'backend' option instead.",
+            )
+            self.backend = "inductor" if self.use_inductor else "eager"
+
+        if self.backend == "":
+            self.backend = "inductor"
+
     def init_backend(self, vllm_config: "VllmConfig") -> Union[str, Callable]:
+        """
+        Initialize the backend for the compilation config from a vllm config.
+        Arguments:
+            vllm_config: The vllm config to initialize the backend from.
+        Returns:
+            The backend for the compilation config.
+        """
+        if self.level is None:
+            raise ValueError(
+                "No compilation level is set. This method should only be \
+                called via vllm config where the level is set if none is \
+                provided."
+            )
         if self.level == CompilationLevel.NO_COMPILATION:
             raise ValueError("No compilation level is set.")
 
@@ -531,15 +580,15 @@ class CompilationConfig:
 
         torch_backends = list_backends(exclude_tags=tuple())
         if self.level in [CompilationLevel.DYNAMO_AS_IS, CompilationLevel.DYNAMO_ONCE]:
-            if self.backend == "":
-                return "eager"
             if self.backend in torch_backends:
                 return self.backend
             return resolve_obj_by_qualname(self.backend)
 
-        # TODO: pass user-specified backend to piecewise compilation
-        # merge with the config use_inductor
         assert self.level == CompilationLevel.PIECEWISE
+        if self.backend not in ["eager", "inductor"]:
+            raise ValueError(
+                f"Invalid backend for piecewise compilation: {self.backend}"
+            )
 
         from vllm.compilation.backends import VllmBackend
 
@@ -692,7 +741,7 @@ class CompilationConfig:
         )
 
         inductor_used = (
-            self.level == CompilationLevel.PIECEWISE and self.use_inductor
+            self.level == CompilationLevel.PIECEWISE and self.backend == "inductor"
         ) or (
             self.level >= CompilationLevel.DYNAMO_AS_IS and self.backend == "inductor"
         )

vllm/config/vllm.py

@@ -318,6 +318,25 @@ class VllmConfig:
                 # NB: Passing both --enforce-eager and a compilation level
                 # in V0 means the compilation level wins out.
                 self.compilation_config.level = CompilationLevel.NO_COMPILATION
+        else:
+            assert self.compilation_config.level >= CompilationLevel.NO_COMPILATION
+            assert self.compilation_config.level <= CompilationLevel.PIECEWISE
+            assert self.compilation_config.level <= 3
+
+        # If user does not set custom ops via none or all set it here based on
+        # compilation level and backend.
+        if (
+            self.compilation_config.custom_ops.count("none")
+            + self.compilation_config.custom_ops.count("all")
+            == 0
+        ):
+            if (
+                self.compilation_config.level > 0
+                and self.compilation_config.backend != "eager"
+            ):
+                self.compilation_config.custom_ops.append("none")
+            else:
+                self.compilation_config.custom_ops.append("all")
 
         # async tp is built on top of sequence parallelism
         # and requires it to be enabled.

vllm/model_executor/custom_op.py

@@ -114,7 +114,9 @@ class CustomOp(nn.Module):
         custom_ops = compilation_config.custom_ops
         if not hasattr(cls, "name"):
             logger.warning_once(
-                "Custom op %s was not registered, which means it won't appear in the op registry. It will be enabled/disabled based on the global settings.",  # noqa: E501
+                "Custom op %s was not registered, which means it won't appear\
+                 in the op registry. It will be enabled/disabled based on the\
+                 global settings.",  # noqa: E501
                 cls.__name__,
             )
             return CustomOp.default_on()
@@ -128,19 +130,17 @@ class CustomOp(nn.Module):
     @staticmethod
     def default_on() -> bool:
         """
-        On by default if PyTorch Inductor is not used.
-        Specifying 'all' or 'none' in custom_op takes precedence.
+        Behavior controlled by `CompilationConfig.custom_ops`: On by default if
+        'all', off by default if 'none'.
+        When PyTorch Inductor is used, 'none' is the default value,
+        otherwise 'all'.
         """
-        from vllm.config import CompilationLevel
-
         compilation_config = get_cached_compilation_config()
-        default_on = (
-            compilation_config.level < CompilationLevel.PIECEWISE
-            or not compilation_config.use_inductor
-        )
         count_none = compilation_config.custom_ops.count("none")
         count_all = compilation_config.custom_ops.count("all")
-        return default_on and not count_none > 0 or count_all > 0
+        assert count_none + count_all == 1
+
+        return not count_none > 0 or count_all > 0
 
     # Dictionary of all custom ops (classes, indexed by registered name).
     # To check if an op with a name is enabled, call .enabled() on the class.

vllm/platforms/cpu.py

@@ -274,8 +274,6 @@ class CpuPlatform(Platform):
                     "epilogue_fusion": True,
                 }
             )
-            if compilation_config.use_inductor:
-                compilation_config.custom_ops = ["none"]
 
         if vllm_config.lora_config is not None:
             compilation_config.level = CompilationLevel.NO_COMPILATION