Add primary weighs fp8 support for mxfp8

tests/pytorch/test_multi_tensor.py

@@ -259,3 +259,35 @@ def test_multi_tensor_compute_scale_and_scale_inv(
         )
         torch.testing.assert_close(scale, scale_ref, rtol=0, atol=0)
         torch.testing.assert_close(scale_inv, scale_inv_ref, rtol=0, atol=0)
+
+
+@pytest.mark.parametrize("input_size_pair", input_size_pairs + [(1, 1)])
+@pytest.mark.parametrize("applier", appliers)
+@pytest.mark.parametrize("repeat", [1, 55])
+def test_multi_tensor_compute_scale_inv_e8m0(input_size_pair, applier, repeat):
+    sizea, sizeb = input_size_pair
+    device = torch.device("cuda")
+    overflow_buf = torch.zeros(1, dtype=torch.int32, device=device)
+    a = torch.randn([sizea], dtype=torch.bfloat16, device=device).abs()
+    b = torch.randn([sizeb], dtype=torch.bfloat16, device=device).abs()
+
+    amax_list = []
+    for _ in range(repeat):
+        amax_list += [a.clone(), b.clone()]
+    scale_inv_list = [torch.empty_like(x).to(torch.uint8) for x in amax_list]
+
+    applier(
+        tex.multi_tensor_compute_scale_inv_e8m0,
+        overflow_buf,
+        [amax_list, scale_inv_list],
+    )
+
+    max_fp8 = torch.finfo(torch.float8_e4m3fn).max
+    for amax, scale_inv in zip(amax_list, scale_inv_list):
+        scale_inv_u32 = (amax.float() / max_fp8).view(torch.int)
+        exponent = scale_inv_u32 // 2**23
+        mantissa = scale_inv_u32 & 0x7FFFFF
+        exponent += (
+            ((mantissa > 0) & (exponent != 0xFE)) & ~((exponent == 0) & (mantissa <= 0x400000))
+        ).to(torch.int)
+        torch.testing.assert_close(exponent.to(torch.uint8), scale_inv)

tests/pytorch/test_partial_cast.py

@@ -0,0 +1,136 @@
+# Copyright (c) 2022-2025, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+#
+# See LICENSE for license information.
+
+import torch
+
+import transformer_engine.pytorch as te
+import transformer_engine_torch as tex
+from transformer_engine_torch import multi_tensor_compute_scale_inv_e8m0
+from transformer_engine.pytorch.optimizers.multi_tensor_apply import multi_tensor_applier
+
+
+def compute_partial_amax_reference(inp, amax_rowwise, amax_colwise, h, w, start_offset):
+    n = inp.view(-1).size(0)
+    if n == h * w:
+        full = inp.view(-1)
+    else:
+        full = torch.zeros(h * w, dtype=inp.dtype, device=inp.device)
+        full[start_offset : start_offset + n].copy_(inp)
+    full = torch.abs(full)
+    _amax_rowwise, _ = torch.max(full.view(h, w // 32, 32), dim=2)
+    amax_rowwise[:h, : (w // 32)].copy_(_amax_rowwise)
+    _amax_colwise, _ = torch.max(full.view(h // 32, 32, w), dim=1)
+    amax_colwise[: (h // 32), :w].copy_(_amax_colwise)
+
+
+def partial_cast_reference(
+    inp, rowwise_out, colwise_out, rowwise_inv_scale, colwise_inv_scale, h, w, start_offset
+):
+    rowwise_scale = ((254 - rowwise_inv_scale.int()) * 2**23).view(torch.float32)
+    colwise_scale = ((254 - colwise_inv_scale.int()) * 2**23).view(torch.float32)
+    n = inp.view(-1).size(0)
+    if n == h * w:
+        full = inp
+    else:
+        full = torch.empty(h * w, dtype=inp.dtype, device=inp.device)
+        full[start_offset : start_offset + n].copy_(inp)
+    full = full.float()
+    rowwise_scale = rowwise_scale[:h, : (w // 32)].contiguous().float()
+    colwise_scale = colwise_scale[: (h // 32), :w].contiguous().float()
+    scaled = (full.view(-1, 32) * rowwise_scale.view(-1, 1)).view(-1)
+    rowwise_out.copy_(
+        scaled[start_offset : start_offset + n].to(torch.float8_e4m3fn).view(rowwise_out.dtype)
+    )
+    scaled = (full.view(h // 32, 32, w) * colwise_scale.view(h // 32, 1, w)).view(-1)
+    colwise_out.copy_(
+        scaled[start_offset : start_offset + n].to(torch.float8_e4m3fn).view(colwise_out.dtype)
+    )
+
+
+def run_one_case(n, h, w, start_offset):
+    inp = torch.randn(n, dtype=torch.bfloat16, device="cuda")
+
+    rowwise_padding = [128, 4]
+    colwise_padding = [4, 128]
+
+    def _pad(x, padding):
+        return (x + padding - 1) // padding * padding
+
+    rowwise_shape = [_pad(h, rowwise_padding[0]), _pad(w // 32, rowwise_padding[1])]
+    colwise_shape = [_pad(h // 32, colwise_padding[0]), _pad(w, colwise_padding[1])]
+
+    # Partial amax cuda kernel
+    amax_rowwise = torch.zeros(*rowwise_shape, dtype=inp.dtype, device=inp.device)
+    amax_colwise = torch.zeros(*colwise_shape, dtype=inp.dtype, device=inp.device)
+    tex.mxfp8_scaling_compute_partial_amax(inp, amax_rowwise, amax_colwise, h, w, start_offset)
+
+    # Partial amax pytorch reference
+    amax_rowwise_ref = torch.zeros(*rowwise_shape, dtype=inp.dtype, device=inp.device)
+    amax_colwise_ref = torch.zeros(*colwise_shape, dtype=inp.dtype, device=inp.device)
+    compute_partial_amax_reference(inp, amax_rowwise_ref, amax_colwise_ref, h, w, start_offset)
+
+    # Check partial amax
+    torch.testing.assert_close(amax_rowwise, amax_rowwise_ref, atol=0, rtol=0)
+    torch.testing.assert_close(amax_colwise, amax_colwise_ref, atol=0, rtol=0)
+
+    # Calculate scales and scale_invs
+    dummy_overflow_buf = torch.empty(1, dtype=torch.int32, device=inp.device)
+    scale_inv_rowwise = torch.empty_like(amax_rowwise).to(torch.uint8)
+    scale_inv_colwise = torch.empty_like(amax_colwise).to(torch.uint8)
+    multi_tensor_applier(
+        multi_tensor_compute_scale_inv_e8m0,
+        dummy_overflow_buf,
+        [
+            [amax_rowwise, amax_colwise],
+            [scale_inv_rowwise, scale_inv_colwise],
+        ],
+    )
+
+    # Partial cast cuda kernel
+    output_rowwise = torch.empty_like(inp).to(torch.uint8)
+    output_colwise = torch.empty_like(inp).to(torch.uint8)
+    tex.mxfp8_scaling_partial_cast(
+        inp,
+        output_rowwise,
+        output_colwise,
+        scale_inv_rowwise,
+        scale_inv_colwise,
+        h,
+        w,
+        start_offset,
+    )
+
+    # Partial cast pytorch reference
+    output_rowwise_ref = torch.empty_like(inp).to(torch.uint8)
+    output_colwise_ref = torch.empty_like(inp).to(torch.uint8)
+    partial_cast_reference(
+        inp,
+        output_rowwise_ref,
+        output_colwise_ref,
+        scale_inv_rowwise,
+        scale_inv_colwise,
+        h,
+        w,
+        start_offset,
+    )
+
+    # Check partial cast results
+    torch.testing.assert_close(output_rowwise, output_rowwise_ref, atol=0, rtol=0)
+    torch.testing.assert_close(output_colwise, output_colwise_ref, atol=0, rtol=0)
+
+
+def test_mxfp8_scaling_partial_cast():
+    run_one_case(3, 32, 64, 31)
+    run_one_case(64 * 64 - 2, 64, 64, 1)
+    run_one_case(16384 * 6144, 16384, 6144, 0)
+    run_one_case(32768, 256, 128, 0)
+    run_one_case(131072, 768, 256, 0)
+    run_one_case(65536, 768, 256, 131072)
+    run_one_case(98304, 128, 768, 0)
+
+
+if __name__ == "__main__":
+
+    torch.cuda.manual_seed(1234)
+    test_mxfp8_scaling_partial_cast()

transformer_engine/common/CMakeLists.txt

@@ -163,6 +163,7 @@ list(APPEND transformer_engine_cuda_sources
      recipe/current_scaling.cu
      recipe/delayed_scaling.cu
      recipe/fp8_block_scaling.cu
+     recipe/mxfp8_scaling.cu
      recipe/nvfp4.cu
      comm_gemm_overlap/userbuffers/userbuffers.cu)
 

transformer_engine/common/include/transformer_engine/multi_tensor.h

@@ -265,6 +265,24 @@ void nvte_multi_tensor_compute_scale_and_scale_inv_cuda(int chunk_size, NVTETens
                                                         float max_fp8, int force_pow_2_scales,
                                                         float epsilon, cudaStream_t stream);
 
+/*!  \brief Compute E8M0 scale_inv for a list of tensors.
+ *
+ * \warning   This API is **experimental** and subject to change.
+ * \warning   Argument device_id is deprecated and will be removed in a future release.
+ *
+ *  \param[in]      chunk_size              Number of tensor elements processed by a CUDA block.
+ *  \param[in]      noop_flag               If this single element tensor has non-zero value, kernel will exit immediately.
+ *  \param[in,out]  tensor_lists            2D array of input tensors.
+ *  \param[in]      num_tensor_lists        Size (dim0) of tensor_lists.
+ *  \param[in]      num_tensors_per_list    Size (dim1) of tensor_lists.
+ *  \param[in]      stream                  CUDA stream used for this operation.
+ */
+void nvte_multi_tensor_compute_scale_inv_e8m0_cuda(int chunk_size, NVTETensor noop_flag,
+                                                   NVTETensor **tensor_lists,
+                                                   const size_t num_tensor_lists,
+                                                   const size_t num_tensors_per_list,
+                                                   cudaStream_t stream);
+
 /*! \brief Split a tensor along dimension 0 and compute the amax for each split.
  *
  *  This function is experimental and the API is not stable.