[Build] Add OpenAI triton_kernels (#28788)

Signed-off-by: Varun Sundar Rabindranath <vsundarr@redhat.com>
Co-authored-by: Varun Sundar Rabindranath <vsundarr@redhat.com>

.gitignore

@@ -4,6 +4,9 @@
 # vllm-flash-attn built from source
 vllm/vllm_flash_attn/*
 
+# OpenAI triton kernels copied from source
+vllm/third_party/triton_kernels/*
+
 # triton jit
 .triton
 

CMakeLists.txt

@@ -1030,6 +1030,11 @@ if(VLLM_GPU_LANG STREQUAL "HIP")
     WITH_SOABI)
 endif()
 
+# For CUDA and HIP builds also build the triton_kernels external package.
+if(VLLM_GPU_LANG STREQUAL "CUDA" OR VLLM_GPU_LANG STREQUAL "HIP")
+    include(cmake/external_projects/triton_kernels.cmake)
+endif()
+
 # For CUDA we also build and ship some external projects.
 if (VLLM_GPU_LANG STREQUAL "CUDA")
     include(cmake/external_projects/flashmla.cmake)

cmake/external_projects/triton_kernels.cmake

@@ -0,0 +1,53 @@
+# Install OpenAI triton_kernels from https://github.com/triton-lang/triton/tree/main/python/triton_kernels
+
+set(DEFAULT_TRITON_KERNELS_TAG "v3.5.0")
+
+# Set TRITON_KERNELS_SRC_DIR for use with local development with vLLM. We expect TRITON_KERNELS_SRC_DIR to
+# be directly set to the triton_kernels python directory. 
+if (DEFINED ENV{TRITON_KERNELS_SRC_DIR})
+  message(STATUS "[triton_kernels] Fetch from $ENV{TRITON_KERNELS_SRC_DIR}")
+  FetchContent_Declare(
+          triton_kernels
+          SOURCE_DIR $ENV{TRITON_KERNELS_SRC_DIR}
+  )
+
+else()
+  set(TRITON_GIT "https://github.com/triton-lang/triton.git")
+  message (STATUS "[triton_kernels] Fetch from ${TRITON_GIT}:${DEFAULT_TRITON_KERNELS_TAG}")
+  FetchContent_Declare(
+          triton_kernels
+          # TODO (varun) : Fetch just the triton_kernels directory from Triton
+          GIT_REPOSITORY https://github.com/triton-lang/triton.git
+          GIT_TAG ${DEFAULT_TRITON_KERNELS_TAG}
+          GIT_PROGRESS TRUE
+          SOURCE_SUBDIR python/triton_kernels/triton_kernels
+  )
+endif()
+
+# Fetch content 
+FetchContent_MakeAvailable(triton_kernels)
+
+if (NOT triton_kernels_SOURCE_DIR)
+  message (FATAL_ERROR "[triton_kernels] Cannot resolve triton_kernels_SOURCE_DIR")
+endif()
+
+if (DEFINED ENV{TRITON_KERNELS_SRC_DIR})
+  set(TRITON_KERNELS_PYTHON_DIR "${triton_kernels_SOURCE_DIR}/")
+else()
+  set(TRITON_KERNELS_PYTHON_DIR "${triton_kernels_SOURCE_DIR}/python/triton_kernels/triton_kernels/")
+endif()
+
+message (STATUS "[triton_kernels] triton_kernels is available at ${TRITON_KERNELS_PYTHON_DIR}")
+
+add_custom_target(triton_kernels)
+
+# Ensure the vllm/third_party directory exists before installation
+install(CODE "file(MAKE_DIRECTORY \"\${CMAKE_INSTALL_PREFIX}/vllm/third_party/triton_kernels\")")
+
+## Copy .py files to install directory.
+install(DIRECTORY
+        ${TRITON_KERNELS_PYTHON_DIR}
+        DESTINATION 
+        vllm/third_party/triton_kernels/
+        COMPONENT triton_kernels
+        FILES_MATCHING PATTERN "*.py")

setup.py

@@ -299,6 +299,20 @@ class cmake_build_ext(build_ext):
             os.makedirs(os.path.dirname(dst_file), exist_ok=True)
             self.copy_file(file, dst_file)
 
+        if _is_cuda() or _is_hip():
+            # copy vllm/third_party/triton_kernels/**/*.py from self.build_lib
+            # to current directory so that they can be included in the editable
+            # build
+            print(
+                f"Copying {self.build_lib}/vllm/third_party/triton_kernels "
+                "to vllm/third_party/triton_kernels"
+            )
+            shutil.copytree(
+                f"{self.build_lib}/vllm/third_party/triton_kernels",
+                "vllm/third_party/triton_kernels",
+                dirs_exist_ok=True,
+            )
+
 
 class precompiled_build_ext(build_ext):
     """Disables extension building when using precompiled binaries."""
@@ -633,6 +647,9 @@ ext_modules = []
 if _is_cuda() or _is_hip():
     ext_modules.append(CMakeExtension(name="vllm._moe_C"))
     ext_modules.append(CMakeExtension(name="vllm.cumem_allocator"))
+    # Optional since this doesn't get built (produce an .so file). This is just
+    # copying the relevant .py files from the source repository.
+    ext_modules.append(CMakeExtension(name="vllm.triton_kernels", optional=True))
 
 if _is_hip():
     ext_modules.append(CMakeExtension(name="vllm._rocm_C"))

vllm/model_executor/layers/quantization/utils/mxfp4_utils.py

@@ -8,6 +8,7 @@ import torch
 from vllm.logger import init_logger
 from vllm.platforms import current_platform
 from vllm.triton_utils import triton
+from vllm.utils.import_utils import has_triton_kernels
 from vllm.utils.torch_utils import direct_register_custom_op, is_torch_equal_or_newer
 
 logger = init_logger(__name__)
@@ -15,6 +16,7 @@ logger = init_logger(__name__)
 
 def _swizzle_mxfp4(quant_tensor, scale, num_warps):
     """weight swizzle for mxfp4 moe, used for OAI mxfp4 kernel"""
+    assert has_triton_kernels()
     import triton_kernels.matmul_ogs_details.opt_flags as opt_flags
     from triton_kernels.numerics import InFlexData
     from triton_kernels.tensor import FP4, convert_layout, wrap_torch_tensor

vllm/utils/import_utils.py

@@ -18,6 +18,10 @@ from typing import Any
 import regex as re
 from typing_extensions import Never
 
+from vllm.logger import init_logger
+
+logger = init_logger(__name__)
+
 
 # TODO: This function can be removed if transformer_modules classes are
 # serialized by value when communicating between processes
@@ -62,6 +66,35 @@ def import_pynvml():
     return pynvml
 
 
+@cache
+def import_triton_kernels():
+    """
+    For convenience, prioritize triton_kernels that is available in
+    `site-packages`. Use `vllm.third_party.triton_kernels` as a fall-back.
+    """
+    if _has_module("triton_kernels"):
+        import triton_kernels
+
+        logger.debug_once(
+            f"Loading module triton_kernels from {triton_kernels.__file__}.",
+            scope="local",
+        )
+    elif _has_module("vllm.third_party.triton_kernels"):
+        import vllm.third_party.triton_kernels as triton_kernels
+
+        logger.debug_once(
+            f"Loading module triton_kernels from {triton_kernels.__file__}.",
+            scope="local",
+        )
+        sys.modules["triton_kernels"] = triton_kernels
+    else:
+        logger.info_once(
+            "triton_kernels unavailable in this build. "
+            "Please consider installing triton_kernels from "
+            "https://github.com/triton-lang/triton/tree/main/python/triton_kernels"
+        )
+
+
 def import_from_path(module_name: str, file_path: str | os.PathLike):
     """
     Import a Python file according to its file path.
@@ -397,7 +430,12 @@ def has_deep_gemm() -> bool:
 
 def has_triton_kernels() -> bool:
     """Whether the optional `triton_kernels` package is available."""
-    return _has_module("triton_kernels")
+    is_available = _has_module("triton_kernels") or _has_module(
+        "vllm.third_party.triton_kernels"
+    )
+    if is_available:
+        import_triton_kernels()
+    return is_available
 
 
 def has_tilelang() -> bool: