integrate mxfp8 dim1 cast kernel choice enum into MXLinear

Author: danielvegamyhre

test/prototype/mx_formats/test_mx_dtensor.py

@@ -25,6 +25,7 @@
 from tqdm import tqdm
 
 from torchao.prototype.mx_formats import MXLinearConfig
+from torchao.prototype.mx_formats.config import MXFP8Dim1CastKernelChoice
 from torchao.prototype.mx_formats.mx_tensor import MXTensor
 from torchao.testing.training.dtensor_utils import (
     _test_lowp_mlp_tensor_parallelism_base,
@@ -82,7 +83,7 @@ def _test_mxfp8_mlp_tensor_parallelism(mesh: DeviceMesh, size=128):
 def _test_mxfp8_mlp_tensor_parallelism_dim1_triton(mesh: DeviceMesh, size=128):
     config = MXLinearConfig.from_recipe_name("mxfp8_emulated")
     config.block_size = 32
-    config.use_fp8_dim1_cast_triton_kernel = True
+    config.mxfp8_dim1_cast_kernel_choice = MXFP8Dim1CastKernelChoice.CUDA
     _test_lowp_mlp_tensor_parallelism_base(
         mesh, config, size, compile=False, allgather_in_lowp=False
     )

test/prototype/mx_formats/test_mx_linear.py

@@ -12,6 +12,7 @@
 import torch.nn.functional as F
 
 from torchao.prototype.mx_formats.config import (
+    MXFP8Dim1CastKernelChoice,
     MXGemmKernelChoice,
     MXInferenceLinearConfig,
     MXLinearConfig,
@@ -81,16 +82,19 @@ def run_around_tests():
 @pytest.mark.parametrize("elem_dtype", elem_dtypes)
 @pytest.mark.parametrize("bias", [True, False])
 @pytest.mark.parametrize("input_shape", [(128, 256), (1, 128, 256), (1, 1, 128, 256)])
-@pytest.mark.parametrize("use_fp8_dim1_cast_triton_kernel", [False, True])
+@pytest.mark.parametrize(
+    "mxfp8_dim1_cast_kernel_choice",
+    [None, MXFP8Dim1CastKernelChoice.TRITON, MXFP8Dim1CastKernelChoice.CUDA],
+)
 def test_linear_eager_vs_hp(
-    elem_dtype, bias, input_shape, use_fp8_dim1_cast_triton_kernel
+    elem_dtype, bias, input_shape, mxfp8_dim1_cast_kernel_choice
 ):
     """
     Smoke test for training linear module with mx weight, compares the following:
     * baseline: float32
     * experiment: emulated MX
     """
-    if use_fp8_dim1_cast_triton_kernel:
+    if mxfp8_dim1_cast_kernel_choice is not None:
         if elem_dtype != (
             torch.float8_e4m3fn,
             torch.float8_e4m3fn,
@@ -109,11 +113,11 @@ def test_linear_eager_vs_hp(
     )
     m_mx = copy.deepcopy(m)
     config = MXLinearConfig(
-        block_size=4,
+        block_size=32,  # Only 32 is supported for now
         elem_dtype=elem_dtype[0],
         elem_dtype_weight_override=elem_dtype[1],
         elem_dtype_grad_output_override=elem_dtype[2],
-        use_fp8_dim1_cast_triton_kernel=use_fp8_dim1_cast_triton_kernel,
+        mxfp8_dim1_cast_kernel_choice=mxfp8_dim1_cast_kernel_choice,
     )
     quantize_(m_mx, config)
 
@@ -227,8 +231,11 @@ def test_activation_checkpointing():
 @pytest.mark.parametrize("bias", [False, True])
 # TODO(future PR): figure out why torch.compile does not match eager when
 # autocast is on
-@pytest.mark.parametrize("use_fp8_dim1_cast_triton_kernel", [False, True])
-def test_linear_compile(hp_dtype, recipe_name, bias, use_fp8_dim1_cast_triton_kernel):
+@pytest.mark.parametrize(
+    "mxfp8_dim1_cast_kernel_choice",
+    [None, MXFP8Dim1CastKernelChoice.TRITON, MXFP8Dim1CastKernelChoice.CUDA],
+)
+def test_linear_compile(hp_dtype, recipe_name, bias, mxfp8_dim1_cast_kernel_choice):
     """
     Verify that compile does not change numerics of MX linear fw + bw
     """
@@ -246,7 +253,7 @@ def test_linear_compile(hp_dtype, recipe_name, bias, use_fp8_dim1_cast_triton_ke
         # TODO(future PR): fix this, things are clearly broken with bias=True
         pytest.skip("this test is broken for non-emulated recipes with bias=True")
 
-    if use_fp8_dim1_cast_triton_kernel:
+    if mxfp8_dim1_cast_kernel_choice is not None:
         if recipe_name not in ("mxfp8_emulated", "mxfp8_cublas"):
             pytest.skip("unsupported configuration")
         if not is_sm_at_least_89():
@@ -267,7 +274,7 @@ def test_linear_compile(hp_dtype, recipe_name, bias, use_fp8_dim1_cast_triton_ke
         nn.Linear(K, N, bias=bias, device="cuda", dtype=hp_dtype),
     )
     config = MXLinearConfig.from_recipe_name(recipe_name)
-    config.use_fp8_dim1_cast_triton_kernel = use_fp8_dim1_cast_triton_kernel
+    config.mxfp8_dim1_cast_kernel_choice = mxfp8_dim1_cast_kernel_choice
 
     quantize_(m_mx, config=config)
     m_mx_c = copy.deepcopy(m_mx)

torchao/prototype/mx_formats/config.py

@@ -33,6 +33,11 @@ class MXGemmKernelChoice(Enum):
     CUBLAS = "cublas"
 
 
+class MXFP8Dim1CastKernelChoice(Enum):
+    TRITON = "triton"
+    CUDA = "cuda"
+
+
 # Pre-made recipes for common configurations
 class MXLinearRecipeName(Enum):
     MXFP8_EMULATED = "mxfp8_emulated"
@@ -85,10 +90,12 @@ class MXLinearConfig(AOBaseConfig):
     # on the given hardware an exception will be thrown
     gemm_kernel_choice: MXGemmKernelChoice = MXGemmKernelChoice.EMULATED
 
-    # If True, uses a custom triton kernel for cast to mxfp8 across dim1
+    # define which kernel to use for dim1 cast
     # TODO(1945): remove this config option once torch.compile gives us
     # a fast kernel
-    use_fp8_dim1_cast_triton_kernel: bool = False
+    mxfp8_dim1_cast_kernel_choice: Optional[MXFP8Dim1CastKernelChoice] = (
+        MXFP8Dim1CastKernelChoice.TRITON
+    )
 
     # If True, uses a custom triton kernel for fp4 dequantize
     use_fp4_custom_triton_dequant_kernel: bool = False
@@ -146,8 +153,7 @@ def short_str(self) -> str:
         if self.elem_dtype_grad_output_override is not None:
             s += f", lp_go_override={DTYPE_TO_SHORT_STR[self.elem_dtype_grad_output_override]}"
         s += f", kernel={self.gemm_kernel_choice.value}"
-        if self.use_fp8_dim1_cast_triton_kernel:
-            s += ", use_fp8_dim1_cast_triton_kernel=True"
+        s += f", mxfp8_dim1_cast_kernel_choice={self.mxfp8_dim1_cast_kernel_choice.value}"
         if self.use_fp4_custom_triton_dequant_kernel:
             s += ", use_fp4_custom_triton_dequant_kernel=True"
         return s

torchao/prototype/mx_formats/mx_linear.py

@@ -15,6 +15,7 @@
 from torch.distributed._tensor import DTensor
 
 from torchao.prototype.mx_formats.config import (
+    MXFP8Dim1CastKernelChoice,
     MXGemmKernelChoice,
     MXInferenceLinearConfig,
     MXLinearConfig,
@@ -134,15 +135,15 @@ def forward(
         grad_elem_dtype: Any,
         block_size: int,
         gemm_kernel_choice: MXGemmKernelChoice,
-        use_fp8_dim1_cast_triton_kernel: bool,
+        mxfp8_dim1_cast_kernel_choice: MXFP8Dim1CastKernelChoice,
     ):
         ctx.save_for_backward(input_hp, weight_hp)
         ctx.in_elem_dtype = in_elem_dtype
         ctx.w_elem_dtype = w_elem_dtype
         ctx.grad_elem_dtype = grad_elem_dtype
         ctx.block_size = block_size
         ctx.gemm_kernel_choice = gemm_kernel_choice
-        ctx.use_fp8_dim1_cast_triton_kernel = use_fp8_dim1_cast_triton_kernel
+        ctx.mxfp8_dim1_cast_kernel_choice = mxfp8_dim1_cast_kernel_choice
 
         # input @ weight_t = output
         input_orig_shape = input_hp.shape
@@ -167,7 +168,7 @@ def backward(ctx, grad_output_hp: torch.Tensor):
         grad_elem_dtype = ctx.grad_elem_dtype
         block_size = ctx.block_size
         gemm_kernel_choice = ctx.gemm_kernel_choice
-        use_fp8_dim1_cast_triton_kernel = ctx.use_fp8_dim1_cast_triton_kernel
+        mxfp8_dim1_cast_kernel_choice = ctx.mxfp8_dim1_cast_kernel_choice
 
         grad_output_orig_shape = grad_output_hp.shape
         grad_output_hp_r = grad_output_hp.reshape(-1, grad_output_orig_shape[-1])
@@ -183,10 +184,14 @@ def backward(ctx, grad_output_hp: torch.Tensor):
             gemm_kernel_choice=gemm_kernel_choice,
         )
 
-        if use_fp8_dim1_cast_triton_kernel:
+        if mxfp8_dim1_cast_kernel_choice == MXFP8Dim1CastKernelChoice.TRITON:
             weight_mx_dim1 = _triton_to_mxfp8_dim1_wrapper(
                 weight_hp, block_size, w_elem_dtype, weight_hp.dtype, gemm_kernel_choice
             )
+        elif mxfp8_dim1_cast_kernel_choice == MXFP8Dim1CastKernelChoice.CUDA:
+            weight_mx_dim1 = _cuda_to_mxfp8_dim1_wrapper(
+                weight_hp, block_size, w_elem_dtype, weight_hp.dtype, gemm_kernel_choice
+            )
         else:
             weight_hp_t_c = weight_hp.t().contiguous()
             weight_mx_dim1 = MXTensor.to_mx(
@@ -201,14 +206,22 @@ def backward(ctx, grad_output_hp: torch.Tensor):
         )
 
         # input_t @ grad_output = grad_weight
-        if use_fp8_dim1_cast_triton_kernel:
+        if mxfp8_dim1_cast_kernel_choice == MXFP8Dim1CastKernelChoice.TRITON:
             grad_output_mx_dim1 = _triton_to_mxfp8_dim1_wrapper(
                 grad_output_hp_r,
                 block_size,
                 grad_elem_dtype,
                 grad_output_hp_r.dtype,
                 gemm_kernel_choice,
             )
+        elif mxfp8_dim1_cast_kernel_choice == MXFP8Dim1CastKernelChoice.CUDA:
+            grad_output_mx_dim1 = _cuda_to_mxfp8_dim1_wrapper(
+                grad_output_hp_r,
+                block_size,
+                grad_elem_dtype,
+                grad_output_hp_r.dtype,
+                gemm_kernel_choice,
+            )
         else:
             grad_output_mx_dim1 = MXTensor.to_mx(
                 grad_output_hp_r.t().contiguous(),
@@ -217,7 +230,7 @@ def backward(ctx, grad_output_hp: torch.Tensor):
                 gemm_kernel_choice=gemm_kernel_choice,
             )
 
-        if use_fp8_dim1_cast_triton_kernel:
+        if mxfp8_dim1_cast_kernel_choice == MXFP8Dim1CastKernelChoice.TRITON:
             input_t_mx_dim0_tmp = _triton_to_mxfp8_dim1_wrapper(
                 input_hp_r,
                 block_size,
@@ -226,6 +239,15 @@ def backward(ctx, grad_output_hp: torch.Tensor):
                 gemm_kernel_choice,
             )
             input_t_mx_dim0 = input_t_mx_dim0_tmp.t()
+        elif mxfp8_dim1_cast_kernel_choice == MXFP8Dim1CastKernelChoice.CUDA:
+            input_t_mx_dim0_tmp = _cuda_to_mxfp8_dim1_wrapper(
+                input_hp_r,
+                block_size,
+                in_elem_dtype,
+                input_hp_r.dtype,
+                gemm_kernel_choice,
+            )
+            input_t_mx_dim0 = input_t_mx_dim0_tmp.t()
         else:
             input_t_mx_dim0_tmp = MXTensor.to_mx(
                 input_hp_r.t().contiguous(),
@@ -280,7 +302,7 @@ def forward(self, x):
             config.elem_dtype_grad_output_override or config.elem_dtype,
             config.block_size,
             config.gemm_kernel_choice,
-            config.use_fp8_dim1_cast_triton_kernel,
+            config.mxfp8_dim1_cast_kernel_choice,
         )
         if self.bias is not None:
             y = y + self.bias