Add test case for compiling multiple graphs (#21044)

Signed-off-by: Yong Hoon Shin <yhshin@meta.com>

tests/compile/piecewise/test_multiple_graphs.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""
+Test (piecewise) compilation with a simple model where multiple submodules
+are compiled and graph captured separately.
+"""
+import torch
+from torch import nn
+from torch.library import Library
+
+from vllm.compilation.backends import set_model_tag
+from vllm.compilation.counter import compilation_counter
+from vllm.compilation.decorators import (ignore_torch_compile,
+                                         support_torch_compile)
+from vllm.config import (CompilationConfig, CompilationLevel, VllmConfig,
+                         set_current_vllm_config)
+from vllm.envs import VLLM_USE_V1
+from vllm.forward_context import set_forward_context
+from vllm.utils import direct_register_custom_op
+
+# create a library to hold the custom op
+silly_lib = Library("silly", "FRAGMENT")  # noqa
+
+BATCH_SIZE = 32
+MLP_SIZE = 128
+HIDDEN_SIZE = 1024
+RANDOM_SEED = 0
+
+
+def silly_attention(q: torch.Tensor, k: torch.Tensor, v: torch.Tensor,
+                    out: torch.Tensor) -> None:
+    out.copy_(q)
+    out += k
+    out += v
+
+
+def silly_attention_fake(q: torch.Tensor, k: torch.Tensor, v: torch.Tensor,
+                         out: torch.Tensor) -> None:
+    return
+
+
+direct_register_custom_op(
+    op_name="attention",
+    op_func=silly_attention,
+    mutates_args=["out"],
+    fake_impl=silly_attention_fake,
+    target_lib=silly_lib,
+)
+
+
+@support_torch_compile
+class ParentModel(nn.Module):
+
+    def __init__(self,
+                 *,
+                 vllm_config: VllmConfig,
+                 prefix: str = '',
+                 **kwargs) -> None:
+        super().__init__()
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        return x
+
+
+class Attention(nn.Module):
+
+    def __init__(self, mlp_size: int, hidden_size: int) -> None:
+        super().__init__()
+        self.pre_attn = nn.Linear(mlp_size, hidden_size, bias=False)
+        self.post_attn = nn.Linear(hidden_size, mlp_size, bias=False)
+        self.rms_norm_weight = nn.Parameter(torch.ones(hidden_size))
+
+        # Initialize to same weights for testing
+        nn.init.xavier_normal_(
+            self.pre_attn.weight.data,
+            generator=torch.Generator().manual_seed(RANDOM_SEED),
+            gain=0.001)
+        nn.init.xavier_normal_(
+            self.post_attn.weight.data,
+            generator=torch.Generator().manual_seed(RANDOM_SEED),
+            gain=0.001)
+
+    def rms_norm_ref(self, x: torch.Tensor) -> torch.Tensor:
+        x_f32 = x.float()
+        return (x_f32 * torch.rsqrt(
+            torch.mean(x_f32.square(), dim=-1, keepdim=True) + 1e-6) *
+                self.rms_norm_weight).to(x.dtype)
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        x = self.pre_attn(x)
+        x = self.rms_norm_ref(x)
+        attn_output = torch.empty_like(x)
+        torch.ops.silly.attention(x, x, x, attn_output)
+        x = attn_output
+        x = self.rms_norm_ref(x)
+        x = self.post_attn(x)
+        return x
+
+
+@support_torch_compile
+class CompiledAttention(nn.Module):
+
+    def __init__(self,
+                 *,
+                 mlp_size: int,
+                 hidden_size: int,
+                 vllm_config: VllmConfig,
+                 prefix: str = '',
+                 **kwargs) -> None:
+        super().__init__()
+        self.attn = Attention(mlp_size, hidden_size)
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        return self.attn(x)
+
+
+@support_torch_compile
+class CompiledAttentionTwo(CompiledAttention):
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        return self.attn(x) + x
+
+
+@ignore_torch_compile
+class SimpleModelWithTwoGraphs(ParentModel):
+
+    def __init__(self,
+                 *,
+                 mlp_size: int,
+                 hidden_size: int,
+                 vllm_config: VllmConfig,
+                 prefix: str = '',
+                 **kwargs) -> None:
+        super().__init__(vllm_config=vllm_config, prefix=prefix)
+        # Test will fail without set_model_tag here with error:
+        # "ValueError: too many values to unpack (expected 3)"
+        # This is because CompiledAttention and CompiledAttentionTwo
+        # have different implmentations but the same torch.compile
+        # cache dir will be used as default prefix is 'model_tag'
+        with set_model_tag("attn_one"):
+            self.attn_one = CompiledAttention(
+                mlp_size=mlp_size,
+                hidden_size=hidden_size,
+                vllm_config=vllm_config,
+                prefix=f"{prefix}.attn_one",
+            )
+        with set_model_tag("attn_two"):
+            self.attn_two = CompiledAttentionTwo(
+                mlp_size=mlp_size,
+                hidden_size=hidden_size,
+                vllm_config=vllm_config,
+                prefix=f"{prefix}.attn_two",
+            )
+
+        self.hidden_states = torch.zeros((BATCH_SIZE, MLP_SIZE)).cuda()
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        bsz = x.shape[0]
+        # CUDAGraph expects same tensor addresses for each run
+        self.hidden_states[:bsz].copy_(x)
+        x = self.attn_one(self.hidden_states[:bsz])
+        self.hidden_states[:bsz].copy_(x)
+        x = self.attn_two(self.hidden_states[:bsz])
+        return x
+
+
+def test_ignore_torch_compile_decorator():
+    assert VLLM_USE_V1
+
+    # piecewise
+    vllm_config = VllmConfig(compilation_config=CompilationConfig(
+        level=CompilationLevel.PIECEWISE,
+        use_cudagraph=True,
+        splitting_ops=["silly.attention"],
+        cudagraph_capture_sizes=[1, 2],
+    ))
+
+    @support_torch_compile
+    class A(nn.Module):
+
+        def __init__(self,
+                     *,
+                     vllm_config: VllmConfig,
+                     prefix: str = '',
+                     **kwargs) -> None:
+            super().__init__()
+
+        def forward(self, x: torch.Tensor) -> torch.Tensor:
+            x = x + x
+            attn_output = torch.empty_like(x)
+            torch.ops.silly.attention(x, x, x, attn_output)
+            x = attn_output
+            x = x * 3
+            return x
+
+    @ignore_torch_compile
+    class B(A):
+        ...
+
+    @support_torch_compile
+    class C(B):
+        ...
+
+    with set_current_vllm_config(vllm_config):
+        mod_A = A(vllm_config=vllm_config, prefix='').eval().cuda()
+
+    # A has support_torch_compile
+    with compilation_counter.expect(
+            num_graphs_seen=1,
+            num_piecewise_graphs_seen=3,
+            num_piecewise_capturable_graphs_seen=2,
+            num_backend_compilations=2,
+            num_cudagraph_captured=4,
+            # num_cudagraph_sizes * num_piecewise_capturable_graphs_seen
+    ), set_forward_context({}, vllm_config=vllm_config):
+        # first run is for compile
+        mod_A(torch.randn(BATCH_SIZE, MLP_SIZE).cuda())
+        # run cudagraph captured sizes
+        mod_A(torch.randn(2, MLP_SIZE).cuda())
+        mod_A(torch.randn(1, MLP_SIZE).cuda())
+
+    with set_current_vllm_config(vllm_config):
+        mod_B = B(vllm_config=vllm_config, prefix='').eval().cuda()
+
+    # B's ignore_torch_compile should override A's support_torch_compile
+    with compilation_counter.expect(
+            num_graphs_seen=0,
+            num_piecewise_graphs_seen=0,
+            num_piecewise_capturable_graphs_seen=0,
+            num_backend_compilations=0,
+            num_cudagraph_captured=0,
+    ), set_forward_context({}, vllm_config=vllm_config):
+        mod_B(torch.randn(BATCH_SIZE, MLP_SIZE).cuda())
+        mod_B(torch.randn(2, MLP_SIZE).cuda())
+        mod_B(torch.randn(1, MLP_SIZE).cuda())
+
+    with set_current_vllm_config(vllm_config):
+        mod_C = C(vllm_config=vllm_config, prefix='').eval().cuda()
+
+    # C's support_torch_compile should override B's ignore_torch_compile
+    with compilation_counter.expect(
+            num_graphs_seen=1,
+            num_piecewise_graphs_seen=3,
+            num_piecewise_capturable_graphs_seen=2,
+            num_backend_compilations=2,
+            num_cudagraph_captured=4,
+            # num_cudagraph_sizes * num_piecewise_capturable_graphs_seen
+    ), set_forward_context({}, vllm_config=vllm_config):
+        mod_C(torch.randn(BATCH_SIZE, MLP_SIZE).cuda())
+        mod_C(torch.randn(2, MLP_SIZE).cuda())
+        mod_C(torch.randn(1, MLP_SIZE).cuda())
+
+
+@torch.inference_mode
+def run_model(vllm_config, model: nn.Module, inputs: torch.Tensor):
+    with set_forward_context({}, vllm_config=vllm_config):
+        # First run is for compile
+        model(inputs)
+
+        # Run CUDAGraph captured sizes
+        model(inputs[:2])
+        model(inputs[:1])
+
+        output = model(inputs[:2])
+
+        output = output.cpu()
+        return output.cpu()
+
+
+def test_multi_graph_piecewise_compile_outputs_equal():
+    outputs = []
+
+    # piecewise compile
+    vllm_config = VllmConfig(compilation_config=CompilationConfig(
+        level=CompilationLevel.PIECEWISE,
+        use_cudagraph=True,
+        splitting_ops=["silly.attention"],
+        cudagraph_capture_sizes=[1, 2],
+    ))
+
+    with set_current_vllm_config(vllm_config):
+        model = SimpleModelWithTwoGraphs(mlp_size=MLP_SIZE,
+                                         hidden_size=HIDDEN_SIZE,
+                                         vllm_config=vllm_config,
+                                         prefix='').eval().cuda()
+
+    # Pre-allocate memory for CUDAGraph which expects
+    # static tensor addresses
+    inputs = torch.randn(BATCH_SIZE, MLP_SIZE).cuda()
+
+    with compilation_counter.expect(
+            num_graphs_seen=2,  # two graphs for the model
+            num_piecewise_graphs_seen=6,
+            # attn_one, attn_two each has 3 piecewise graphs
+            # (pre attn, post attn, silly_attention) each
+            num_piecewise_capturable_graphs_seen=4,
+            # attn_one, attn_two has pre attn and post attn each, total=4
+            num_backend_compilations=4,  # num_piecewise_capturable_graphs_seen
+            num_cudagraph_captured=8,
+            # num_cudagraph_sizes * num_piecewise_capturable_graphs_seen
+    ):
+        outputs.append(run_model(vllm_config, model, inputs))
+
+    # no compile or cudagraph
+    vllm_config = VllmConfig(compilation_config=CompilationConfig(
+        level=CompilationLevel.NO_COMPILATION, ))
+
+    with set_current_vllm_config(vllm_config):
+        model = SimpleModelWithTwoGraphs(mlp_size=MLP_SIZE,
+                                         hidden_size=HIDDEN_SIZE,
+                                         vllm_config=vllm_config,
+                                         prefix='').eval().cuda()
+
+    with compilation_counter.expect(
+            num_graphs_seen=0,
+            num_piecewise_graphs_seen=0,
+            num_piecewise_capturable_graphs_seen=0,
+            num_backend_compilations=0,
+            num_cudagraph_captured=0,
+    ):
+        outputs.append(run_model(vllm_config, model, inputs))
+
+    # piecewise compile without CUDA graph
+    vllm_config = VllmConfig(compilation_config=CompilationConfig(
+        level=CompilationLevel.PIECEWISE,
+        use_cudagraph=False,
+        splitting_ops=["silly.attention"],
+    ))
+
+    with set_current_vllm_config(vllm_config):
+        model = SimpleModelWithTwoGraphs(mlp_size=MLP_SIZE,
+                                         hidden_size=HIDDEN_SIZE,
+                                         vllm_config=vllm_config,
+                                         prefix='').eval().cuda()
+
+    with compilation_counter.expect(
+            num_graphs_seen=2,
+            num_piecewise_graphs_seen=6,
+            num_piecewise_capturable_graphs_seen=4,
+            num_backend_compilations=4,
+            num_cudagraph_captured=0,  # no cudagraph captured
+    ):
+        outputs.append(run_model(vllm_config, model, inputs))
+
+    # Generally don't expect outputs with and without inductor
+    # to be bitwise equivalent
+    assert torch.allclose(outputs[0], outputs[1])
+
+    # Expect bitwise equivalence using inductor w/ and w/o cudagraph
+    assert torch.equal(outputs[0], outputs[2])

vllm/compilation/compiler_interface.py

@@ -423,6 +423,12 @@ class InductorAdaptor(CompilerInterface):
             if is_torch_equal_or_newer("2.6"):
                 stack.enter_context(
                     torch._inductor.config.patch(fx_graph_remote_cache=False))
+                # InductorAdaptor (unfortunately) requires AOTAutogradCache
+                # to be turned off to run. It will fail to acquire the hash_str
+                # and error if not.
+                # StandaloneInductorAdaptor (PyTorch 2.8+) fixes this problem.
+                stack.enter_context(
+                    torch._functorch.config.patch(enable_autograd_cache=False))
                 stack.enter_context(
                     torch._functorch.config.patch(
                         enable_remote_autograd_cache=False))

vllm/compilation/decorators.py

@@ -20,9 +20,38 @@ from .monitor import start_monitoring_torch_compile
 
 logger = init_logger(__name__)
 
+IGNORE_COMPILE_KEY = "_ignore_compile_vllm"
+
 _T = TypeVar("_T", bound=type[nn.Module])
 
 
+def ignore_torch_compile(cls: _T) -> _T:
+    """
+    A decorator to ignore support_torch_compile decorator
+    on the class. This is useful when a parent class has
+    a support_torch_compile decorator, but we don't want to
+    compile the class `cls` that inherits the parent class.
+    This only ignores compiling the forward of the class the
+    decorator is applied to. 
+
+    If the parent has ignore_torch_compile but the child has
+    support_torch_compile, the child will still be compiled.
+    
+    If the class has one or more submodules
+    that have support_torch_compile decorator applied, compile will
+    not be ignored for those submodules.
+    """
+    setattr(cls, IGNORE_COMPILE_KEY, True)
+    return cls
+
+
+def _should_ignore_torch_compile(cls) -> bool:
+    """
+    Check if the class should be ignored for torch.compile.
+    """
+    return getattr(cls, IGNORE_COMPILE_KEY, False)
+
+
 @overload
 def support_torch_compile(
     *,
@@ -148,6 +177,8 @@ def _support_torch_compile(
 
     old_init = cls.__init__
 
+    setattr(cls, IGNORE_COMPILE_KEY, False)
+
     def __init__(self, *, vllm_config: VllmConfig, prefix: str = '', **kwargs):
         old_init(self, vllm_config=vllm_config, prefix=prefix, **kwargs)
         self.vllm_config = vllm_config
@@ -156,9 +187,11 @@ def _support_torch_compile(
         self.do_not_compile = \
             vllm_config.compilation_config.level in [
             CompilationLevel.NO_COMPILATION, CompilationLevel.DYNAMO_AS_IS
-        ] or not supports_dynamo()
+        ] or not supports_dynamo() or _should_ignore_torch_compile(
+            self.__class__)
         if self.do_not_compile:
             return
+
         compilation_counter.num_models_seen += 1
         TorchCompileWrapperWithCustomDispatcher.__init__(
             self, compilation_level=vllm_config.compilation_config.level)