[Blockwise] Add support block_len=64 support

Add env to chose blocklen of blockwise quantize.
Signed-off-by: wenjh <wenjh@sugon.com>

Fix pytest of blockwise error
Signed-off-by: wenjh <wenjh@sugon.com>

Resolve new api in  int8 gemm test
Signed-off-by: wenjh <wenjh@sugon.com>

Fix incorrect launch parm
Signed-off-by: wenjh <wenjh@sugon.com>

Fix 1D blockwise(64) acc error
Signed-off-by: wenjh <wenjh@sugon.com>

tests/cpp/operator/test_cast_float8blockwise.cu

@@ -25,7 +25,11 @@ struct QuantizationOptions {
   size_t block_scaling_dim = 2u;
 };
 
+#ifdef __HIP_PLATFORM_AMD__
+size_t kBlockLen = static_cast<size_t>(blockwise_fp8_block_len());
+#else
 constexpr size_t kBlockLen = 128;
+#endif
 
 enum ProcessingMethod {
   CAST_ONLY,
@@ -80,8 +84,13 @@ template <typename InputType, typename OutputType>
 void ref_quantize(const ProcessingMethod processing_method, const InputType* input,
                   const std::pair<size_t, size_t>& input_hw, OutputType* output, float* scale_inv,
                   OutputType* output_t, float* scale_inv_t, const QuantizationOptions& opts) {
+#ifdef __HIP_PLATFORM_AMD__
+  size_t kBlockLenX = kBlockLen;
+  size_t kBlockLenY = kBlockLen;
+#else
   constexpr size_t kBlockLenX = kBlockLen;
   constexpr size_t kBlockLenY = kBlockLen;
+#endif
 
   auto quantize_element = [](InputType element, float qscale) -> OutputType {
     // Scale in FP32 and cast result to nearest FP8.
@@ -157,7 +166,11 @@ void ref_quantize_onedimensional_blocks(const ProcessingMethod processing_method
   float input_type_max_val = Quantized_Limits<InputType>::max();
   float quant_type_max_val = Quantized_Limits<OutputType>::max();
 
+#ifdef __HIP_PLATFORM_AMD__
+  size_t kBlockLenX = kBlockLen;
+#else
   constexpr size_t kBlockLenX = kBlockLen;
+#endif
 
   auto quantize_element = [](InputType element, float qscale) -> OutputType {
     // Scale in FP32 and cast result to nearest FP8.

tests/cpp/test_common.cu

@@ -168,13 +168,13 @@ std::pair<scale_inv_meta, scale_inv_meta> get_scales(const NVTEShape& shape,
     scale_inv_meta ret_rowwise, ret_colwise;
 
     {
-      auto scale_dim_0 = DIVUP(first_dim, static_cast<size_t>(128));
-      auto scale_dim_1 = DIVUP(DIVUP(last_dim, static_cast<size_t>(128)), 4) * 4;
+      auto scale_dim_0 = DIVUP(first_dim, static_cast<size_t>(blockwise_fp8_block_len()));
+      auto scale_dim_1 = DIVUP(DIVUP(last_dim, static_cast<size_t>(blockwise_fp8_block_len())), 4) * 4;
       ret_rowwise.shape = {scale_dim_0, scale_dim_1};
     }
     {
-      auto scale_dim_0 = DIVUP(last_dim, static_cast<size_t>(128));
-      auto scale_dim_1 = DIVUP(DIVUP(first_dim, static_cast<size_t>(128)), 4) * 4;
+      auto scale_dim_0 = DIVUP(last_dim, static_cast<size_t>(blockwise_fp8_block_len()));
+      auto scale_dim_1 = DIVUP(DIVUP(first_dim, static_cast<size_t>(blockwise_fp8_block_len())), 4) * 4;
       ret_colwise.shape = {scale_dim_0, scale_dim_1};
     }
     ret_rowwise.type = DType::kFloat32;
@@ -194,12 +194,12 @@ std::pair<scale_inv_meta, scale_inv_meta> get_scales(const NVTEShape& shape,
     scale_inv_meta ret_rowwise, ret_colwise;
 
     {
-      auto scale_dim_0 = DIVUP(last_dim, static_cast<size_t>(128));
+      auto scale_dim_0 = DIVUP(last_dim, static_cast<size_t>(blockwise_fp8_block_len()));
       auto scale_dim_1 = DIVUP(first_dim, 4) * 4;
       ret_rowwise.shape = {scale_dim_0, scale_dim_1};
     }
     {
-      auto scale_dim_0 = DIVUP(first_dim, static_cast<size_t>(128));
+      auto scale_dim_0 = DIVUP(first_dim, static_cast<size_t>(blockwise_fp8_block_len()));
       auto scale_dim_1 = DIVUP(last_dim, 4) * 4;
       ret_colwise.shape = {scale_dim_0, scale_dim_1};
     }

tests/cpp/test_common.h

@@ -22,6 +22,18 @@
 namespace test {
 using namespace transformer_engine;
 
+inline int blockwise_fp8_block_len() {
+  const char *env = std::getenv("NVTE_BLOCKWISE_FP8_BLOCK_LEN");
+  if (env == nullptr || env[0] == '\0') {
+    return 128;
+  }
+  int value;
+  std::istringstream iss(env);
+  iss >> value;
+  NVTE_CHECK(iss, "Invalid environment variable value");
+  return value;
+}
+
 template <size_t i>
 struct BytesToType {};
 

tests/pytorch/references/blockwise_fp8_gemm_reference.py

@@ -8,6 +8,7 @@ import torch
 import triton
 import triton.language as tl
 from torch.utils.cpp_extension import IS_HIP_EXTENSION
+from transformer_engine.pytorch.fp8 import blockwise_fp8_block_len
 
 
 @triton.jit
@@ -135,7 +136,7 @@ class CuBLASRefBlockwiseGemm:
         N, K_w = qw.shape
         assert K == K_w, "K dimension mismatch between qx and qw"
 
-        tile_len = 128
+        tile_len = blockwise_fp8_block_len
         # Calculate grid sizes without padding
         grid_m = (M + tile_len - 1) // tile_len
         grid_n = (N + tile_len - 1) // tile_len

tests/pytorch/references/blockwise_quantizer_reference.py

@@ -7,7 +7,7 @@ import math
 import torch
 from typing import Optional, Protocol, Tuple
 from references.quantize_scale_calc import scale_from_amax_tensor
-
+from transformer_engine.pytorch.fp8 import blockwise_fp8_block_len
 
 @dataclasses.dataclass()
 class QuantizeResult:
@@ -277,7 +277,7 @@ class BlockwiseQuantizerReference:
         return_transpose: bool = False,
         eps: float = 0.0,
         pow_2_scales: bool = False,
-        quant_tile_shape: Tuple[int, int] = (128, 128),
+        quant_tile_shape: Tuple[int, int] = (blockwise_fp8_block_len, blockwise_fp8_block_len),
     ) -> QuantizeResult:
         # sanity checks
         assert x.dim() == 2
@@ -293,7 +293,7 @@ class BlockwiseQuantizerReference:
             torch.int8,
         ), "Unsupported quant dtype."
 
-        assert quant_tile_shape in ((1, 128), (128, 128))
+        assert quant_tile_shape in ((1, blockwise_fp8_block_len), (blockwise_fp8_block_len, blockwise_fp8_block_len))
         if quant_tile_shape[0] == 1:
             # Quantize row-wise
             return self.scale_munger.munge_scale_shapes_for_backend(

tests/pytorch/test_float8_blockwise_gemm_exact.py

@@ -8,7 +8,7 @@ import transformer_engine as te
 import transformer_engine_torch as tex
 
 from transformer_engine.pytorch.constants import TE_DType
-from transformer_engine.pytorch.fp8 import FP8GlobalStateManager
+from transformer_engine.pytorch.fp8 import (FP8GlobalStateManager, blockwise_fp8_block_len)
 from transformer_engine.pytorch.tensor.float8_blockwise_tensor import (
     Float8BlockQuantizer,
     Float8BlockwiseQTensor,
@@ -77,8 +77,9 @@ def cublas_gemm_fp8_blockwise_case(
 
     assert not (use_bias and use_grad), "Bias grad not supported by GEMM"
     # Set quantize_op and quantization parameters
-    x_quant_tile_shape = (1, 128) if is_x_1d_scaled else (128, 128)
-    w_quant_tile_shape = (1, 128) if is_w_1d_scaled else (128, 128)
+    block_len = blockwise_fp8_block_len
+    x_quant_tile_shape = (1, block_len) if is_x_1d_scaled else (block_len, block_len)
+    w_quant_tile_shape = (1, block_len) if is_w_1d_scaled else (block_len, block_len)
     x_block_scaling_dim = 1 if is_x_1d_scaled else 2
     w_block_scaling_dim = 1 if is_w_1d_scaled else 2
     x_te_dtype = TE_DType[x_dtype]
@@ -247,8 +248,9 @@ def cublas_gemm_test_constraint_enforced(
         out = None
 
     # Set quantize_op and quantization parameters
-    x_quant_tile_shape = (1, 128) if is_x_1d_scaled else (128, 128)
-    w_quant_tile_shape = (1, 128) if is_w_1d_scaled else (128, 128)
+    block_len = blockwise_fp8_block_len
+    x_quant_tile_shape = (1, block_len) if is_x_1d_scaled else (block_len, block_len)
+    w_quant_tile_shape = (1, block_len) if is_w_1d_scaled else (block_len, block_len)
     x_block_scaling_dim = 1 if is_x_1d_scaled else 2
     w_block_scaling_dim = 1 if is_w_1d_scaled else 2
     x_te_dtype = TE_DType[x_dtype]

tests/pytorch/test_float8_blockwise_scaling_exact.py

@@ -10,7 +10,7 @@ import pytest
 import torch
 import transformer_engine as te
 import transformer_engine_torch as tex
-from transformer_engine.pytorch.fp8 import FP8GlobalStateManager
+from transformer_engine.pytorch.fp8 import (FP8GlobalStateManager, blockwise_fp8_block_len)
 from transformer_engine.common.recipe import Float8BlockScaling
 from transformer_engine.pytorch.constants import TE_DType
 from transformer_engine.pytorch.tensor.float8_blockwise_tensor import (
@@ -99,9 +99,9 @@ def check_quantization_block_tiling_versus_reference(
     tile_size: Tuple[int, int],
 ) -> None:
     te_dtype = TE_DType[quant_dtype]
-    if tile_size == (1, 128):
+    if tile_size in ((1, 128), (1, 64)):
         block_scaling_dim = 1
-    elif tile_size == (128, 128):
+    elif tile_size in ((128, 128), (64, 64)):
         block_scaling_dim = 2
     else:
         raise ValueError("Non support tile size")
@@ -214,7 +214,7 @@ def check_quantization_block_tiling_versus_reference(
     "return_transpose", [True, False], ids=["quantize_transpose", "quantize_only"]
 )
 @pytest.mark.parametrize("pow_2_scales", [True], ids=["pow2scales"])
-@pytest.mark.parametrize("tile_size", [(1, 128), (128, 128)], ids=["1DTile", "2DTile"])
+@pytest.mark.parametrize("tile_size", [(1, 128), (128, 128), (1, 64), (64, 64)], ids=["1D128Tile", "2D128Tile", "1D64Tile", "2D64Tile"])
 def test_quantization_block_tiling_versus_reference(
     x_dtype: torch.dtype,
     M: int,
@@ -225,6 +225,8 @@ def test_quantization_block_tiling_versus_reference(
     pow_2_scales: bool,
     tile_size: Tuple[int, int],
 ) -> None:
+    if blockwise_fp8_block_len != tile_size[1]:
+        pytest.skip("Block len of blockwise is skipped by env.")
     check_quantization_block_tiling_versus_reference(
         x_dtype, M, N, quant_dtype, eps, return_transpose, pow_2_scales, tile_size
     )
@@ -249,7 +251,7 @@ def test_quantization_block_tiling_versus_reference(
     "return_transpose", [True, False], ids=["quantize_transpose", "quantize_only"]
 )
 @pytest.mark.parametrize("pow_2_scales", [False], ids=["fp32scales"])
-@pytest.mark.parametrize("tile_size", [(1, 128), (128, 128)], ids=["1DTile", "2DTile"])
+@pytest.mark.parametrize("tile_size", [(1, 128), (128, 128), (1, 64), (64, 64)], ids=["1D128Tile", "2D128Tile", "1D64Tile", "2D64Tile"])
 def test_quantization_block_tiling_versus_reference_fp32_scales(
     x_dtype: torch.dtype,
     M: int,
@@ -260,6 +262,8 @@ def test_quantization_block_tiling_versus_reference_fp32_scales(
     pow_2_scales: bool,
     tile_size: Tuple[int, int],
 ) -> None:
+    if blockwise_fp8_block_len != tile_size[1]:
+        pytest.skip("Block len of blockwise is skipped by env.")
     check_quantization_block_tiling_versus_reference(
         x_dtype, M, N, quant_dtype, eps, return_transpose, pow_2_scales, tile_size
     )
@@ -277,7 +281,7 @@ def test_quantization_block_tiling_versus_reference_fp32_scales(
 @pytest.mark.parametrize("quant_dtype", [torch.int8, torch.float8_e4m3fn, torch.float8_e5m2], ids=str)
 @pytest.mark.parametrize("eps", [0], ids=["eps_0"])
 @pytest.mark.parametrize("pow_2_scales", [True, False], ids=["pow2scales", "fp32scales"])
-@pytest.mark.parametrize("tile_size", [(128, 128)])
+@pytest.mark.parametrize("tile_size", [(128, 128), (64, 64)], ids=["2D128Tile", "2D64Tile"])
 @pytest.mark.parametrize("extrema_high", [False, True], ids=["zeros", "maxes"])
 def test_quantization_block_tiling_extrema_versus_reference(
     x_dtype: torch.dtype,
@@ -291,10 +295,12 @@ def test_quantization_block_tiling_extrema_versus_reference(
 ) -> None:
     # This test runs a single tile through a quantizer as a way to test
     # branch coverage of scale computation.
+    if blockwise_fp8_block_len != tile_size[1]:
+        pytest.skip("Block len of blockwise is skipped by env.")
     te_dtype = TE_DType[quant_dtype]
-    if tile_size == (1, 128):
+    if tile_size in ((1, 128), (1, 64)):
         block_scaling_dim = 1
-    elif tile_size == (128, 128):
+    elif tile_size in ((128, 128), (64, 64)):
         block_scaling_dim = 2
     else:
         raise ValueError("Non support tile size")

tests/pytorch/test_int8_blockwise_gemm_exact.py

@@ -4,7 +4,7 @@ import transformer_engine as te
 import transformer_engine_torch as tex
 
 from transformer_engine.pytorch.constants import TE_DType
-from transformer_engine.pytorch.fp8 import FP8GlobalStateManager
+from transformer_engine.pytorch.fp8 import (FP8GlobalStateManager, blockwise_fp8_block_len)
 from transformer_engine.pytorch.tensor.float8_blockwise_tensor import (
     Float8BlockQuantizer,
     Float8BlockwiseQTensor,
@@ -82,8 +82,9 @@ def cublas_gemm_fp8_blockwise_case_fw(
 
     assert not (use_bias and use_grad), "Bias grad not supported by GEMM"
     # Set quantize_op and quantization parameters
-    x_quant_tile_shape = (1, 128) if is_x_1d_scaled else (128, 128)
-    w_quant_tile_shape = (1, 128) if is_w_1d_scaled else (128, 128)
+    block_len = blockwise_fp8_block_len
+    x_quant_tile_shape = (1, block_len) if is_x_1d_scaled else (block_len, block_len)
+    w_quant_tile_shape = (1, block_len) if is_w_1d_scaled else (block_len, block_len)
     x_block_scaling_dim = 1 if is_x_1d_scaled else 2
     w_block_scaling_dim = 1 if is_w_1d_scaled else 2
     x_te_dtype = TE_DType[x_dtype]
@@ -196,7 +197,7 @@ def cublas_gemm_fp8_blockwise_case_fw(
     ref_scales_w = qw._columnwise_scale_inv if w_columnwise else qw._rowwise_scale_inv
 
     y, _ = w8a8_block_int8_matmul(
-        qx_data, qw_data, ref_scales_x, ref_scales_w, [128, 128],
+        qx_data, qw_data, ref_scales_x, ref_scales_w, [block_len, block_len],
         output_dtype=out_dtype
     )
 
@@ -265,8 +266,9 @@ def cublas_gemm_fp8_blockwise_case_bw_xgrad(
 
     assert not (use_bias and use_grad), "Bias grad not supported by GEMM"
     # Set quantize_op and quantization parameters
-    dout_quant_tile_shape = (1, 128) if is_dout_1d_scaled else (128, 128)
-    w_quant_tile_shape = (1, 128) if is_w_1d_scaled else (128, 128)
+    block_len = blockwise_fp8_block_len
+    dout_quant_tile_shape = (1, block_len) if is_dout_1d_scaled else (block_len, block_len)
+    w_quant_tile_shape = (1, block_len) if is_w_1d_scaled else (block_len, block_len)
     dout_block_scaling_dim = 1 if is_dout_1d_scaled else 2
     w_block_scaling_dim = 1 if is_w_1d_scaled else 2
     dout_te_dtype = TE_DType[dout_dtype]
@@ -373,7 +375,7 @@ def cublas_gemm_fp8_blockwise_case_bw_xgrad(
     ref_scales_w = qw._columnwise_scale_inv if w_columnwise else qw._rowwise_scale_inv
 
     y, _ = w8a8_block_int8_matmul(
-        qdout_data, qw_data, ref_scales_dout, ref_scales_w, [128, 128],
+        qdout_data, qw_data, ref_scales_dout, ref_scales_w, [block_len, block_len],
         output_dtype=dx_dtype
     )
 
@@ -441,8 +443,9 @@ def cublas_gemm_fp8_blockwise_case_bw_wgrad(
 
     assert not (use_bias and use_grad), "Bias grad not supported by GEMM"
     # Set quantize_op and quantization parameters
-    dout_quant_tile_shape = (1, 128) if is_dout_1d_scaled else (128, 128)
-    x_quant_tile_shape = (1, 128) if is_x_1d_scaled else (128, 128)
+    block_len = blockwise_fp8_block_len
+    dout_quant_tile_shape = (1, block_len) if is_dout_1d_scaled else (block_len, block_len)
+    x_quant_tile_shape = (1, block_len) if is_x_1d_scaled else (block_len, block_len)
     dout_block_scaling_dim = 1 if is_dout_1d_scaled else 2
     x_block_scaling_dim = 1 if is_x_1d_scaled else 2
     dout_te_dtype = TE_DType[dout_dtype]
@@ -552,7 +555,8 @@ def cublas_gemm_fp8_blockwise_case_bw_wgrad(
     # print(f"ref_scales_dout.shape: {ref_scales_dout.shape}, ref_scales_x.shape: {ref_scales_x.shape}")
 
     y, _ = w8a8_block_int8_matmul_wgrad(
-        qdout_data, qx_data, ref_scales_dout, ref_scales_x, [128, 128],
+        qdout_data, qx_data, ref_scales_dout, ref_scales_x, dw.clone() if accumulate else None,
+        accumulate, [block_len, block_len],
         output_dtype=dw_dtype
     )
 

transformer_engine/common/common.h

@@ -6,6 +6,7 @@
 
 #ifndef TRANSFORMER_ENGINE_COMMON_COMMON_H_
 #define TRANSFORMER_ENGINE_COMMON_COMMON_H_
+#include "util/system.h"
 #ifndef __HIP_PLATFORM_AMD__
 #include <cudaTypedefs.h>
 #endif
@@ -33,6 +34,10 @@ namespace transformer_engine {
 std::string to_string(const DType type);
 std::string to_string(const NVTEScalingMode &mode);
 
+inline int blockwise_fp8_block_len() {
+  return ::transformer_engine::getenv<int>("NVTE_BLOCKWISE_FP8_BLOCK_LEN", 128);
+}
+
 inline bool is_tensor_scaling(const NVTEScalingMode &mode) {
   return mode == NVTE_DELAYED_TENSOR_SCALING;
 }

transformer_engine/common/recipe/fp8_block_scaling.cu

@@ -14,6 +14,7 @@
 namespace transformer_engine {
 namespace fp8_block_scaling_recipe {
 
+constexpr int kTileDim64 = 64;
 constexpr int kTileDim = 128;
 constexpr int kThreadsPerBlock = 256;
 
@@ -116,10 +117,10 @@ __global__ void __launch_bounds__(kThreadsPerBlock)
       if (h_in_input < h && w_in_input < w && idx_in_input >= start_offset &&
           idx_in_input < end_offset) {
         float inp = static_cast<float>(input_minus_offset[idx_in_input]) * scale;
-        if constexpr(std::is_same_v<OType, int8_t>) {
-          smem[h_in_smem][w_in_smem] = static_cast<OType>(lroundf(fmaxf(-127.0f, fminf(127.0f, inp))));
-        }
-        else {
+        if constexpr (std::is_same_v<OType, int8_t>) {
+          smem[h_in_smem][w_in_smem] =
+              static_cast<OType>(lroundf(fmaxf(-127.0f, fminf(127.0f, inp))));
+        } else {
           smem[h_in_smem][w_in_smem] = static_cast<OType>(inp);
         }
         skip_store = false;
@@ -175,11 +176,171 @@ __global__ void __launch_bounds__(kThreadsPerBlock)
   }
 }
 
+template <typename IType>
+__global__ void __launch_bounds__(kThreadsPerBlock)
+    fp8_block_scaling_block_len64_compute_partial_amax_kernel(
+        const IType *input, float *amax_ptr, const size_t amax_stride_h, const size_t amax_stride_w,
+        const size_t h, const size_t w, const size_t start_offset, const size_t len) {
+  constexpr int kThreadsPerWarp = 32;
+  constexpr int kLoopsPerRow = kTileDim64 / kThreadsPerWarp;
+  constexpr int kNumWarps = kThreadsPerBlock / kThreadsPerWarp;
+  constexpr int kLoopsPerCol = kTileDim64 / kNumWarps;
+
+  const int tile_col = blockIdx.x;
+  const int tile_row = blockIdx.y;
+  const size_t end_offset = start_offset + len;
+  const IType *input_minus_offset = input - start_offset;
+
+  __shared__ float smem[kNumWarps];
+  float amax = 0.0f;
+
+  for (int loop_col = 0; loop_col < kLoopsPerCol; ++loop_col) {
+    size_t r = tile_row * kTileDim64 + loop_col * kNumWarps + threadIdx.x / kThreadsPerWarp;
+    for (int loop_row = 0; loop_row < kLoopsPerRow; ++loop_row) {
+      size_t c =
+          tile_col * kTileDim64 + loop_row * kThreadsPerWarp + (threadIdx.x % kThreadsPerWarp);
+      size_t idx = r * w + c;
+      if (r < h && c < w && idx >= start_offset && idx < end_offset) {
+        float other_amax = fabs(static_cast<float>(input_minus_offset[idx]));
+        __builtin_assume(amax >= 0);
+        __builtin_assume(other_amax >= 0);
+        amax = fmaxf(amax, other_amax);
+      }
+    }
+  }
+
+  for (int delta = kThreadsPerWarp / 2; delta > 0; delta /= 2) {
+#ifdef __HIP_PLATFORM_AMD__
+    float other_amax = __shfl_down(amax, delta, kThreadsPerWarp);
+#else
+    float other_amax = __shfl_down_sync(0xFFFFFFFF, amax, delta);
+#endif
+    __builtin_assume(amax >= 0);
+    __builtin_assume(other_amax >= 0);
+    amax = fmaxf(amax, other_amax);
+  }
+
+  if (threadIdx.x % kThreadsPerWarp == 0) {
+    smem[threadIdx.x / kThreadsPerWarp] = amax;
+  }
+
+  __syncthreads();
+
+  if (threadIdx.x == 0) {
+    for (int i = 0; i < kNumWarps; ++i) {
+      float other_amax = smem[i];
+      __builtin_assume(amax >= 0);
+      __builtin_assume(other_amax >= 0);
+      amax = fmaxf(amax, other_amax);
+    }
+    amax_ptr[tile_row * amax_stride_h + tile_col * amax_stride_w] = amax;
+  }
+}
+
+template <typename IType, typename OType, bool kWidthAligned>
+__global__ void __launch_bounds__(kThreadsPerBlock)
+    fp8_block_scaling_block_len64_partial_cast_kernel(const IType *input, OType *output,
+                                                      const float *scale_ptr,
+                                                      const size_t scale_stride_h,
+                                                      const size_t scale_stride_w, const size_t h,
+                                                      const size_t w, const size_t start_offset,
+                                                      const size_t len) {
+  using transformer_engine::Vec;
+
+  static_assert(sizeof(OType) == 1);
+  constexpr int kNumOutputElemsPerBank = 4 / sizeof(OType);
+  constexpr int kThreadsPerWarp = 32;
+  constexpr int kLoopsPerRow = kTileDim64 / kThreadsPerWarp;
+  constexpr int kNumWarps = kThreadsPerBlock / kThreadsPerWarp;
+  constexpr int kRowsPerWarp = kTileDim64 / kNumWarps;
+
+  __shared__ OType smem[kTileDim64][kTileDim64 + kNumOutputElemsPerBank];
+
+  const int tile_w = blockIdx.x;
+  const int tile_h = blockIdx.y;
+  const size_t end_offset = start_offset + len;
+  const IType *input_minus_offset = input - start_offset;
+  OType *output_minus_offset = output - start_offset;
+
+  const float scale = scale_ptr[tile_h * scale_stride_h + tile_w * scale_stride_w];
+
+  // Load input data into shared memory
+  bool skip_store = true;
+  for (int i = 0; i < kRowsPerWarp; ++i) {
+    for (int j = 0; j < kLoopsPerRow; ++j) {
+      const int h_in_smem = threadIdx.x / kThreadsPerWarp * kRowsPerWarp + i;
+      const int w_in_smem = threadIdx.x % kThreadsPerWarp + kThreadsPerWarp * j;
+      const int h_in_input = tile_h * kTileDim64 + h_in_smem;
+      const int w_in_input = tile_w * kTileDim64 + w_in_smem;
+      const size_t idx_in_input = static_cast<size_t>(h_in_input) * w + w_in_input;
+      if (h_in_input < h && w_in_input < w && idx_in_input >= start_offset &&
+          idx_in_input < end_offset) {
+        float inp = static_cast<float>(input_minus_offset[idx_in_input]) * scale;
+        if constexpr (std::is_same_v<OType, int8_t>) {
+          smem[h_in_smem][w_in_smem] =
+              static_cast<OType>(lroundf(fmaxf(-127.0f, fminf(127.0f, inp))));
+        } else {
+          smem[h_in_smem][w_in_smem] = static_cast<OType>(inp);
+        }
+        skip_store = false;
+      }
+    }
+  }
+
+  for (int delta = kThreadsPerWarp / 2; delta > 0; delta /= 2) {
+#ifdef __HIP_PLATFORM_AMD__
+    bool other_skip_store = __shfl_down(skip_store, delta, kThreadsPerWarp);
+#else
+    bool other_skip_store = __shfl_down_sync(0xFFFFFFFF, skip_store, delta);
+#endif
+    skip_store = skip_store && other_skip_store;
+  }
+#ifdef __HIP_PLATFORM_AMD__
+  skip_store = __shfl(skip_store, 0, kThreadsPerWarp);
+#else
+  skip_store = __shfl_sync(0xFFFFFFFF, skip_store, 0);
+#endif
+  if (skip_store) {
+    return;
+  }
+
+  // Store the casted data into the output.
+  // Note that this store operation might write "out-of-bounds", but it is intentional:
+  //   1. The "out-of-bounds" here only crosses the boundary of the "local shard" (i.e., the region
+  //      from start_offset to end_offset), not the boundary of the entire output memory. Therefore,
+  //      this out-of-bounds write will not cause illegal memory access.
+  //   2. We assume that the subsequent all-gather operation happens in-place, so any parts that
+  //      should not be updated here will be overwritten by the all-gather.
+  // This tricky approach allows us to avoid checking whether each output index falls within
+  // [start, end), resulting in a significant performance improvement.
+  Vec<OType, kNumOutputElemsPerBank> vec_output;
+  for (int i = 0; i < kRowsPerWarp; ++i) {
+    const int row_in_smem = threadIdx.x / kThreadsPerWarp * kRowsPerWarp + i;
+    const int col_in_smem = threadIdx.x % kThreadsPerWarp * kNumOutputElemsPerBank;
+    for (int j = 0; j < kNumOutputElemsPerBank; ++j) {
+      vec_output.data.elt[j] = smem[row_in_smem][col_in_smem + j];
+    }
+    const int row_in_output = tile_h * kTileDim64 + row_in_smem;
+    const int col_in_output = tile_w * kTileDim64 + col_in_smem;
+    const size_t idx_in_output = static_cast<size_t>(row_in_output) * w + col_in_output;
+    if (row_in_output < h) {
+      if constexpr (kWidthAligned) {
+        vec_output.store_to(output_minus_offset + idx_in_output);
+      } else {
+        int num = min(static_cast<size_t>(kNumOutputElemsPerBank),
+                      static_cast<size_t>(col_in_output < w ? w - col_in_output : 0));
+        vec_output.store_to_elts(output_minus_offset, idx_in_output, num);
+      }
+    }
+  }
+}
+
 void fp8_block_scaling_compute_partial_amax(const Tensor inp, Tensor amax, size_t h, size_t w,
                                             size_t amax_stride_h, size_t amax_stride_w,
                                             size_t start_offset, size_t block_len,
                                             cudaStream_t stream) {
-  NVTE_CHECK(block_len == 128, "Currently only block_len = 128 is supported");
+  NVTE_CHECK(block_len == 128 || block_len == 64,
+             "Currently only block_len = 128 or 64 is supported");
 
   size_t len = inp.numel();
 
@@ -187,26 +348,39 @@ void fp8_block_scaling_compute_partial_amax(const Tensor inp, Tensor amax, size_
   assert(start_offset < h * w);
   assert(start_offset + len <= h * w);
 
-  size_t blocks_x = (w + kTileDim - 1) / kTileDim;
-  size_t blocks_y = (h + kTileDim - 1) / kTileDim;
+  size_t blocks_x = (w + block_len - 1) / block_len;
+  size_t blocks_y = (h + block_len - 1) / block_len;
   assert(blocks_x <= std::numeric_limits<unsigned int>::max());
   assert(blocks_y <= std::numeric_limits<unsigned int>::max());
   dim3 grid(blocks_x, blocks_y);
 
   TRANSFORMER_ENGINE_TYPE_SWITCH_NON_FP8ONLY(
-      inp.dtype(), inp_dtype,
-      fp8_block_scaling_compute_partial_amax_kernel<inp_dtype>
-      <<<grid, kThreadsPerBlock, 0, stream>>>(reinterpret_cast<const inp_dtype *>(inp.data.dptr),
-                                              reinterpret_cast<float *>(amax.data.dptr),
-                                              amax_stride_h, amax_stride_w, h, w, start_offset,
-                                              len);)
+      inp.dtype(), inp_dtype, while (true) {
+        if (128 == block_len) {
+          fp8_block_scaling_compute_partial_amax_kernel<inp_dtype>
+              <<<grid, kThreadsPerBlock, 0, stream>>>(
+                  reinterpret_cast<const inp_dtype *>(inp.data.dptr),
+                  reinterpret_cast<float *>(amax.data.dptr), amax_stride_h, amax_stride_w, h, w,
+                  start_offset, len);
+          break;
+        }
+        if (64 == block_len) {
+          fp8_block_scaling_block_len64_compute_partial_amax_kernel<inp_dtype>
+              <<<grid, kThreadsPerBlock, 0, stream>>>(
+                  reinterpret_cast<const inp_dtype *>(inp.data.dptr),
+                  reinterpret_cast<float *>(amax.data.dptr), amax_stride_h, amax_stride_w, h, w,
+                  start_offset, len);
+          break;
+        }
+      })
 }
 
 void fp8_block_scaling_partial_cast(const Tensor inp, Tensor out, const Tensor scale, size_t h,
                                     size_t w, size_t scale_stride_h, size_t scale_stride_w,
                                     size_t start_offset, size_t block_len, const DType out_dtype,
                                     cudaStream_t stream) {
-  NVTE_CHECK(block_len == 128, "Currently only block_len = 128 is supported");
+  NVTE_CHECK(block_len == 128 || block_len == 64,
+             "Currently only block_len = 128 or 64 is supported");
 
   size_t len = inp.numel();
 
@@ -214,8 +388,8 @@ void fp8_block_scaling_partial_cast(const Tensor inp, Tensor out, const Tensor s
   assert(start_offset < h * w);
   assert(start_offset + len <= h * w);
 
-  size_t blocks_x = (w + kTileDim - 1) / kTileDim;
-  size_t blocks_y = (h + kTileDim - 1) / kTileDim;
+  size_t blocks_x = (w + block_len - 1) / block_len;
+  size_t blocks_y = (h + block_len - 1) / block_len;
   assert(blocks_x <= std::numeric_limits<unsigned int>::max());
   assert(blocks_y <= std::numeric_limits<unsigned int>::max());
   dim3 grid(blocks_x, blocks_y);
@@ -225,13 +399,27 @@ void fp8_block_scaling_partial_cast(const Tensor inp, Tensor out, const Tensor s
       TRANSFORMER_ENGINE_TYPE_SWITCH_8BIT(
           out_dtype, fp8_type,
           TRANSFORMER_ENGINE_SWITCH_CONDITION(
-              w % kTileDim == 0, kWidthAligned,
-              fp8_block_scaling_partial_cast_kernel<inp_dtype, fp8_type, kWidthAligned>
-              <<<grid, kThreadsPerBlock, 0, stream>>>(
-                  reinterpret_cast<const inp_dtype *>(inp.data.dptr),
-                  reinterpret_cast<fp8_type *>(out.data.dptr),
-                  reinterpret_cast<const float *>(scale.data.dptr), scale_stride_h, scale_stride_w,
-                  h, w, start_offset, len);)))
+              w % block_len == 0, kWidthAligned, while (true) {
+                if (128 == block_len) {
+                  fp8_block_scaling_partial_cast_kernel<inp_dtype, fp8_type, kWidthAligned>
+                      <<<grid, kThreadsPerBlock, 0, stream>>>(
+                          reinterpret_cast<const inp_dtype *>(inp.data.dptr),
+                          reinterpret_cast<fp8_type *>(out.data.dptr),
+                          reinterpret_cast<const float *>(scale.data.dptr), scale_stride_h,
+                          scale_stride_w, h, w, start_offset, len);
+                  break;
+                }
+                if (64 == block_len) {
+                  fp8_block_scaling_block_len64_partial_cast_kernel<inp_dtype, fp8_type,
+                                                                    kWidthAligned>
+                      <<<grid, kThreadsPerBlock, 0, stream>>>(
+                          reinterpret_cast<const inp_dtype *>(inp.data.dptr),
+                          reinterpret_cast<fp8_type *>(out.data.dptr),
+                          reinterpret_cast<const float *>(scale.data.dptr), scale_stride_h,
+                          scale_stride_w, h, w, start_offset, len);
+                  break;
+                }
+              })))
 }
 
 }  // namespace fp8_block_scaling_recipe

transformer_engine/common/transpose/quantize_transpose_square_blockwise.cu

@@ -39,6 +39,7 @@ constexpr size_t WARP_TILE_DIM_Y = 64;
 constexpr size_t THREAD_TILE_DIM_X = 16;
 constexpr size_t THREAD_TILE_DIM_Y = 4;
 #else
+constexpr size_t BLOCK_TILE_DIM64 = 64;
 constexpr size_t BLOCK_TILE_DIM = 128;
 constexpr size_t WARP_TILE_DIM_X = 64;
 constexpr size_t WARP_TILE_DIM_Y = 32;
@@ -60,6 +61,11 @@ constexpr size_t NUM_WARPS_X_IN_BLOCK = BLOCK_TILE_DIM / WARP_TILE_DIM_X;
 constexpr size_t NUM_WARPS_Y_IN_BLOCK = BLOCK_TILE_DIM / WARP_TILE_DIM_Y;
 constexpr size_t NUM_WARPS_IN_BLOCK = NUM_WARPS_X_IN_BLOCK * NUM_WARPS_Y_IN_BLOCK;
 
+constexpr size_t THREADS_PER_BLOCK64 = BLOCK_TILE_DIM64 * BLOCK_TILE_DIM64 / ELE_PER_THREAD;
+constexpr size_t NUM_WARPS_X_IN_BLOCK64 = BLOCK_TILE_DIM64 / WARP_TILE_DIM_X;
+constexpr size_t NUM_WARPS_Y_IN_BLOCK64 = BLOCK_TILE_DIM64 / WARP_TILE_DIM_Y;
+constexpr size_t NUM_WARPS_IN_BLOCK64 = NUM_WARPS_X_IN_BLOCK64 * NUM_WARPS_Y_IN_BLOCK64;
+
 constexpr size_t NUM_THREADS_X_IN_WARP = WARP_TILE_DIM_X / THREAD_TILE_DIM_X;
 constexpr size_t NUM_THREADS_Y_IN_WARP = kThreadsPerWarp / NUM_THREADS_X_IN_WARP;
 
@@ -188,14 +194,14 @@ __global__ void __launch_bounds__(THREADS_PER_BLOCK)
       CType scale_data = block_tile_scale;
 
       OType scaled_elt = 0;
-      if constexpr(std::is_same_v<OType, int8_t>) {
-          scaled_elt =
-            static_cast<OType>(lroundf(fmaxf(-127.0f, fminf(127.0f, static_cast<CType>(thrd_tile_input[i].data.elt[j]) * scale_data))));
-        }
-        else {
-          scaled_elt =
+      if constexpr (std::is_same_v<OType, int8_t>) {
+        scaled_elt = static_cast<OType>(lroundf(
+            fmaxf(-127.0f,
+                  fminf(127.0f, static_cast<CType>(thrd_tile_input[i].data.elt[j]) * scale_data))));
+      } else {
+        scaled_elt =
             static_cast<OType>(static_cast<CType>(thrd_tile_input[i].data.elt[j]) * scale_data);
-        }
+      }
       tmp_output_c.data.elt[j] = scaled_elt;
       // Step 4: do transpose within thread tile
       if constexpr (kReturnTranspose) {
@@ -439,13 +445,384 @@ __global__ void __launch_bounds__(THREADS_PER_BLOCK) block_scaled_cast_transpose
         // Step 3: Store cast output
         CType scale_data = block_tile_scale;
         OType scaled_elt = 0;
-        if constexpr(std::is_same_v<OType, int8_t>) {
+        if constexpr (std::is_same_v<OType, int8_t>) {
+          scaled_elt = static_cast<OType>(lroundf(fmaxf(
+              -127.0f,
+              fminf(127.0f, static_cast<CType>(thrd_tile_input[i].data.elt[j]) * scale_data))));
+        } else {
           scaled_elt =
-            static_cast<OType>(lroundf(fmaxf(-127.0f, fminf(127.0f, static_cast<CType>(thrd_tile_input[i].data.elt[j]) * scale_data))));
+              static_cast<OType>(static_cast<CType>(thrd_tile_input[i].data.elt[j]) * scale_data);
         }
-        else {
-          scaled_elt =
+        tmp_output_c.data.elt[j] = scaled_elt;
+        // Step 4: do transpose within thread tile
+        if constexpr (kReturnTranspose) {
+          thrd_tile_out_trans[j].data.elt[i] = scaled_elt;
+        }
+      }
+      tmp_output_c.store_to_elts(output_c + thread_tile_start_idx + i * row_length, 0,
+                                 thread_tile_ncols);
+    }
+
+    if constexpr (kReturnTranspose) {
+      const size_t block_tile_t_start_idx =
+          tile_id_x * BLOCK_TILE_DIM * num_rows + tile_id_y * BLOCK_TILE_DIM;
+      const size_t warp_tile_t_start_idx =
+          block_tile_t_start_idx +
+          warp_id_in_block_x * THREAD_TILE_DIM_X * NUM_THREADS_X_IN_WARP * num_rows +
+          warp_id_in_block_y * THREAD_TILE_DIM_Y * NUM_THREADS_Y_IN_WARP;
+      const size_t thread_tile_t_start_idx = warp_tile_t_start_idx +
+                                             tid_in_warp_x * THREAD_TILE_DIM_X * num_rows +
+                                             tid_in_warp_y * THREAD_TILE_DIM_Y;
+#pragma unroll
+      for (int i = 0; i < thread_tile_ncols; i++) {
+        thrd_tile_out_trans[i].store_to_elts(output_t + thread_tile_t_start_idx + i * num_rows, 0,
+                                             thread_tile_nrows);
+      }
+    }
+  }
+}
+
+template <bool kReturnTranspose, typename CType, typename IType, typename OType>
+__global__ void __launch_bounds__(THREADS_PER_BLOCK64)
+    block_scaled_block_len64_cast_transpose_kernel(
+        const IType* const input, OType* const output_c, OType* const output_t,
+        CType* const tile_scales_inv_c, CType* const tile_scales_inv_t, const size_t row_length,
+        const size_t num_rows, const size_t scale_stride_x, const size_t scale_stride_y,
+        const size_t scale_t_stride_x, const size_t scale_t_stride_y, const float epsilon,
+        bool pow_2_scaling) {
+  using IVec = Vec<IType, THREAD_TILE_DIM_X>;
+  using OVecCast = Vec<OType, THREAD_TILE_DIM_X>;
+  using OVecTrans = Vec<OType, THREAD_TILE_DIM_Y>;
+
+  // shared mem for amax reduction in entire block, each warp produces one amax, there are
+  // NUM_WARPS_IN_BLOCK amax to reduce
+  __shared__ CType block_tile_amax_shared[NUM_WARPS_IN_BLOCK64];
+
+  IVec thrd_tile_input[THREAD_TILE_DIM_Y];
+  constexpr int THREAD_TILE_DIM_X_ = kReturnTranspose ? THREAD_TILE_DIM_X : 1;
+  OVecTrans thrd_tile_out_trans[THREAD_TILE_DIM_X_];
+
+  const int tid_in_warp = threadIdx.x % kThreadsPerWarp;
+  const int tid_in_warp_x = tid_in_warp % NUM_THREADS_X_IN_WARP;
+  const int tid_in_warp_y = tid_in_warp / NUM_THREADS_X_IN_WARP;
+  const int warp_id_in_block = threadIdx.x / kThreadsPerWarp;
+  const int warp_id_in_block_x = warp_id_in_block % NUM_WARPS_X_IN_BLOCK64;
+  const int warp_id_in_block_y = warp_id_in_block / NUM_WARPS_X_IN_BLOCK64;
+
+  // This is ONLY true if the input is a full tile
+  const int tile_id_x = blockIdx.x;
+  const int tile_id_y = blockIdx.y;
+
+  const size_t block_tile_start_idx =
+      tile_id_y * BLOCK_TILE_DIM64 * row_length + tile_id_x * BLOCK_TILE_DIM64;
+  const size_t warp_tile_start_idx =
+      block_tile_start_idx +
+      warp_id_in_block_y * THREAD_TILE_DIM_Y * NUM_THREADS_Y_IN_WARP * row_length +
+      warp_id_in_block_x * THREAD_TILE_DIM_X * NUM_THREADS_X_IN_WARP;
+  const size_t thread_tile_start_idx = warp_tile_start_idx +
+                                       tid_in_warp_y * THREAD_TILE_DIM_Y * row_length +
+                                       tid_in_warp_x * THREAD_TILE_DIM_X;
+
+  CType warp_tile_amax;
+  CType block_tile_amax;
+  CType block_tile_scale;
+  CType amax = 0;
+
+// Step 1: Load a block tile of input data into thread tiles on registers
+#pragma unroll
+  for (int i = 0; i < THREAD_TILE_DIM_Y; i++) {
+    thrd_tile_input[i].load_from(input + thread_tile_start_idx + i * row_length);
+  }
+
+  // Step 2: calculate block tile amax and scale
+  // Calculate thread_tile amax
+  for (int i = 0; i < THREAD_TILE_DIM_Y; i++) {
+#pragma unroll
+    for (int j = 0; j < THREAD_TILE_DIM_X; j++) {
+      __builtin_assume(amax >= 0);
+      amax = fmaxf(amax, fabsf(static_cast<CType>(thrd_tile_input[i].data.elt[j])));
+    }
+  }
+  // Reduce amax in the warp (32x32 tile)
+  warp_tile_amax = warp_reduce_max<kThreadsPerWarp>(amax);
+  // broadcast the amax to all threads in a warp from the lane 0
+  constexpr int lane_zero = 0;
+#ifdef __HIP_PLATFORM_AMD__
+  warp_tile_amax = __shfl(warp_tile_amax, lane_zero, THREADS_PER_WARP);
+#else
+  warp_tile_amax = __shfl_sync(0xFFFFFFFF, warp_tile_amax, lane_zero);
+#endif
+
+  // reduce warp_tile_amax across multiple warps in a thread block using shared mem
+  if (tid_in_warp == 0) {
+    block_tile_amax_shared[warp_id_in_block_y * NUM_WARPS_X_IN_BLOCK64 + warp_id_in_block_x] =
+        warp_tile_amax;
+  }
+  __syncthreads();
+  // only 8 elements needs reduction, if using reduction tree, multiple _syncthreads will be needed,
+  // instead we just let thread 0 do the job
+  if (threadIdx.x == 0) {
+    CType blk_amax = block_tile_amax_shared[0];
+#pragma unroll
+    for (int idx = 1; idx < NUM_WARPS_IN_BLOCK64; idx++) {
+      blk_amax = fmaxf(blk_amax, block_tile_amax_shared[idx]);
+    }
+    block_tile_amax_shared[0] = blk_amax;
+  }
+  __syncthreads();
+  block_tile_amax = block_tile_amax_shared[0];
+
+  block_tile_scale =
+      compute_scale_from_types<IType, OType>(block_tile_amax, epsilon, pow_2_scaling);
+
+  if (threadIdx.x == 0) {
+    static_assert(std::is_same<CType, float>::value);
+    const CType scale_inv = 1.0f / block_tile_scale;
+
+    size_t row_idx = tile_id_y;
+    size_t col_idx = tile_id_x;
+    tile_scales_inv_c[row_idx * scale_stride_y + col_idx * scale_stride_x] = scale_inv;
+
+    if constexpr (kReturnTranspose) {
+      row_idx = tile_id_x;
+      col_idx = tile_id_y;
+      tile_scales_inv_t[row_idx * scale_t_stride_y + col_idx * scale_t_stride_x] = scale_inv;
+    }
+  }
+
+  // Step 3: Store cast output, Step 4: do transpose within thread tile
+  OVecCast tmp_output_c;
+
+  for (int i = 0; i < THREAD_TILE_DIM_Y; i++) {
+#pragma unroll
+    for (int j = 0; j < THREAD_TILE_DIM_X; j++) {
+      // Step 3: Store cast output
+      CType scale_data = block_tile_scale;
+
+      OType scaled_elt = 0;
+      if constexpr (std::is_same_v<OType, int8_t>) {
+        scaled_elt = static_cast<OType>(lroundf(
+            fmaxf(-127.0f,
+                  fminf(127.0f, static_cast<CType>(thrd_tile_input[i].data.elt[j]) * scale_data))));
+      } else {
+        scaled_elt =
             static_cast<OType>(static_cast<CType>(thrd_tile_input[i].data.elt[j]) * scale_data);
+      }
+      tmp_output_c.data.elt[j] = scaled_elt;
+      // Step 4: do transpose within thread tile
+      if constexpr (kReturnTranspose) {
+        thrd_tile_out_trans[j].data.elt[i] = scaled_elt;
+      }
+    }
+    tmp_output_c.store_to(output_c + thread_tile_start_idx + i * row_length);
+  }
+
+  // Step 4: store transpose into shared memory
+  if constexpr (kReturnTranspose) {
+    // Step 4 Alternative (when TMA is not available, skip writing to shared memory)
+    const size_t block_tile_t_start_idx =
+        tile_id_x * BLOCK_TILE_DIM64 * num_rows + tile_id_y * BLOCK_TILE_DIM64;
+    const size_t warp_tile_t_start_idx =
+        block_tile_t_start_idx +
+        warp_id_in_block_x * THREAD_TILE_DIM_X * NUM_THREADS_X_IN_WARP * num_rows +
+        warp_id_in_block_y * THREAD_TILE_DIM_Y * NUM_THREADS_Y_IN_WARP;
+    const size_t thread_tile_t_start_idx = warp_tile_t_start_idx +
+                                           tid_in_warp_x * THREAD_TILE_DIM_X * num_rows +
+                                           tid_in_warp_y * THREAD_TILE_DIM_Y;
+#pragma unroll
+    for (int i = 0; i < THREAD_TILE_DIM_X; i++) {
+      thrd_tile_out_trans[i].store_to(output_t + thread_tile_t_start_idx + i * num_rows);
+    }
+  }
+}
+
+template <bool kReturnTranspose, typename CType, typename IType, typename OType>
+__global__ void __launch_bounds__(THREADS_PER_BLOCK64)
+    block_scaled_block_len64_cast_transpose_kernel_notaligned(
+        const IType* const input, OType* const output_c, OType* const output_t,
+        CType* const tile_scales_inv_c, CType* const tile_scales_inv_t, const size_t row_length,
+        const size_t num_rows, const size_t scale_stride_x, const size_t scale_stride_y,
+        const size_t scale_t_stride_x, const size_t scale_t_stride_y, const float epsilon,
+        bool pow_2_scaling) {
+  using IVec = Vec<IType, THREAD_TILE_DIM_X>;
+  using OVecCast = Vec<OType, THREAD_TILE_DIM_X>;
+  using OVecTrans = Vec<OType, THREAD_TILE_DIM_Y>;
+
+  // shared mem for amax reduction in entire block, each warp produces one amax, there are
+  // NUM_WARPS_IN_BLOCK amax to reduce
+  __shared__ CType block_tile_amax_shared[NUM_WARPS_IN_BLOCK64];
+
+  IVec thrd_tile_input[THREAD_TILE_DIM_Y];
+  constexpr int THREAD_TILE_DIM_X_ = kReturnTranspose ? THREAD_TILE_DIM_X : 1;
+  OVecTrans thrd_tile_out_trans[THREAD_TILE_DIM_X_];
+
+  const int tid_in_warp = threadIdx.x % kThreadsPerWarp;
+  const int tid_in_warp_x = tid_in_warp % NUM_THREADS_X_IN_WARP;
+  const int tid_in_warp_y = tid_in_warp / NUM_THREADS_X_IN_WARP;
+  const int warp_id_in_block = threadIdx.x / kThreadsPerWarp;
+  const int warp_id_in_block_x = warp_id_in_block % NUM_WARPS_X_IN_BLOCK64;
+  const int warp_id_in_block_y = warp_id_in_block / NUM_WARPS_X_IN_BLOCK64;
+
+  const int tile_id_x = blockIdx.x;
+  const int tile_id_y = blockIdx.y;
+
+  const size_t block_tile_start_row_idx = tile_id_y * BLOCK_TILE_DIM64;
+  const size_t block_tile_start_col_idx = tile_id_x * BLOCK_TILE_DIM64;
+  const size_t block_tile_start_idx =
+      block_tile_start_row_idx * row_length + block_tile_start_col_idx;
+  const size_t warp_tile_start_idx =
+      block_tile_start_idx +
+      warp_id_in_block_y * THREAD_TILE_DIM_Y * NUM_THREADS_Y_IN_WARP * row_length +
+      warp_id_in_block_x * THREAD_TILE_DIM_X * NUM_THREADS_X_IN_WARP;
+  const size_t thread_tile_start_idx = warp_tile_start_idx +
+                                       tid_in_warp_y * THREAD_TILE_DIM_Y * row_length +
+                                       tid_in_warp_x * THREAD_TILE_DIM_X;
+
+  // handle non-full tile
+  // check for three cases: full thread tile, nonfull thread tile, empty thread tile
+  // for empty thread tile, directly write zero to the transposed shared mem buffer
+  // for nonfull thread tile, fill zero to thread tile and act as if it's full
+  const size_t thread_tile_start_row_idx =
+      tile_id_y * BLOCK_TILE_DIM64 +
+      warp_id_in_block_y * THREAD_TILE_DIM_Y * NUM_THREADS_Y_IN_WARP +
+      tid_in_warp_y * THREAD_TILE_DIM_Y;
+  const size_t thread_tile_start_col_idx =
+      tile_id_x * BLOCK_TILE_DIM64 +
+      warp_id_in_block_x * THREAD_TILE_DIM_X * NUM_THREADS_X_IN_WARP +
+      tid_in_warp_x * THREAD_TILE_DIM_X;
+
+  const size_t thread_tile_end_row_idx = thread_tile_start_row_idx + THREAD_TILE_DIM_Y - 1;
+  const size_t thread_tile_end_col_idx = thread_tile_start_col_idx + THREAD_TILE_DIM_X - 1;
+
+  bool full_thrd_tile =
+      (thread_tile_end_row_idx < num_rows) && (thread_tile_end_col_idx < row_length);
+  bool empty_thrd_tile =
+      (thread_tile_start_row_idx >= num_rows) || (thread_tile_start_col_idx >= row_length);
+  bool nonfull_thrd_tile = (!full_thrd_tile) && (!empty_thrd_tile);
+
+  const size_t thread_tile_ncols =
+      MIN(THREAD_TILE_DIM_X,
+          (MIN(thread_tile_end_col_idx, row_length - 1) - thread_tile_start_col_idx + 1));
+  const size_t thread_tile_nrows =
+      MIN(THREAD_TILE_DIM_Y,
+          (MIN(thread_tile_end_row_idx, num_rows - 1) - thread_tile_start_row_idx + 1));
+
+  CType warp_tile_amax;
+  CType block_tile_amax;
+  CType block_tile_scale;
+  CType amax = 0;
+
+  if (!empty_thrd_tile) {
+    // Step 1: Load a block tile of input data into thread tiles on registers
+    // Edge case: nonfull thread tile case, will use the partial load function here
+    if (nonfull_thrd_tile) {
+#pragma unroll
+      for (int i = 0; i < THREAD_TILE_DIM_Y; i++) {
+        if (i >= thread_tile_nrows) {
+          thrd_tile_input[i].clear();
+        } else {
+          thrd_tile_input[i].load_from_elts(input + thread_tile_start_idx + i * row_length, 0,
+                                            thread_tile_ncols);
+        }
+      }
+    } else {
+#pragma unroll
+      for (int i = 0; i < THREAD_TILE_DIM_Y; i++) {
+        thrd_tile_input[i].load_from_elts(input + thread_tile_start_idx + i * row_length, 0,
+                                          THREAD_TILE_DIM_X);
+      }
+    }
+
+    // Step 2: calculate block tile amax and scale
+    // Calculate thread_tile amax
+    for (int i = 0; i < THREAD_TILE_DIM_Y; i++) {
+#pragma unroll
+      for (int j = 0; j < THREAD_TILE_DIM_X; j++) {
+        __builtin_assume(amax >= 0);
+        amax = fmaxf(amax, fabsf(static_cast<CType>(thrd_tile_input[i].data.elt[j])));
+      }
+    }
+  }
+  // Reduce amax in the warp (32x32 tile)
+  warp_tile_amax = warp_reduce_max<kThreadsPerWarp>(amax);
+  // broadcast the amax to all threads in a warp from the lane 0
+  constexpr int lane_zero = 0;
+#ifdef __HIP_PLATFORM_AMD__
+  warp_tile_amax = __shfl(warp_tile_amax, lane_zero, THREADS_PER_WARP);
+#else
+  warp_tile_amax = __shfl_sync(0xFFFFFFFF, warp_tile_amax, lane_zero);
+#endif
+
+  // reduce warp_tile_amax across multiple warps in a thread block using shared mem
+  if (tid_in_warp == 0) {
+    block_tile_amax_shared[warp_id_in_block_y * NUM_WARPS_X_IN_BLOCK64 + warp_id_in_block_x] =
+        warp_tile_amax;
+  }
+  __syncthreads();
+  // only 8 elements needs reduction, if using reduction tree, multiple _syncthreads will be needed,
+  // instead we just let thread 0 do the job
+  if (threadIdx.x == 0) {
+    CType blk_amax = block_tile_amax_shared[0];
+#pragma unroll
+    for (int idx = 1; idx < NUM_WARPS_IN_BLOCK64; idx++) {
+      blk_amax = fmaxf(blk_amax, block_tile_amax_shared[idx]);
+    }
+    block_tile_amax_shared[0] = blk_amax;
+  }
+  __syncthreads();
+  block_tile_amax = block_tile_amax_shared[0];
+
+  block_tile_scale =
+      compute_scale_from_types<IType, OType>(block_tile_amax, epsilon, pow_2_scaling);
+
+  if (threadIdx.x == 0) {
+    static_assert(std::is_same<CType, float>::value);
+    const CType scale_inv = 1.0f / block_tile_scale;
+
+    size_t row_idx = tile_id_y;
+    size_t col_idx = tile_id_x;
+    tile_scales_inv_c[row_idx * scale_stride_y + col_idx * scale_stride_x] = scale_inv;
+
+    if constexpr (kReturnTranspose) {
+      row_idx = tile_id_x;
+      col_idx = tile_id_y;
+      tile_scales_inv_t[row_idx * scale_t_stride_y + col_idx * scale_t_stride_x] = scale_inv;
+    }
+  }
+
+  // Step 3: Store cast output, Step 4: do transpose within thread tile
+  // Edge case: in the non-full tile case, there are three subcases
+  // for full thread tile, it's the same thing here
+  // for nonfull thread tile, pay attention when saving tmp_output_c to global
+  // memory, cannot vec store_to, but need to elt store to for empty tile,
+  // it should not enter this step, skip to Step 4
+
+  // set thrd_tile_out_trans to all zero
+  if constexpr (kReturnTranspose) {
+#pragma unroll
+    for (int j = 0; j < THREAD_TILE_DIM_X; j++) {
+      thrd_tile_out_trans[j].clear();
+    }
+  }
+
+  if (!empty_thrd_tile) {
+    OVecCast tmp_output_c;
+    for (int i = 0; i < THREAD_TILE_DIM_Y; i++) {
+      if (i >= thread_tile_nrows) {
+        continue;
+      }
+#pragma unroll
+      for (int j = 0; j < THREAD_TILE_DIM_X; j++) {
+        // Step 3: Store cast output
+        CType scale_data = block_tile_scale;
+        OType scaled_elt = 0;
+        if constexpr (std::is_same_v<OType, int8_t>) {
+          scaled_elt = static_cast<OType>(lroundf(fmaxf(
+              -127.0f,
+              fminf(127.0f, static_cast<CType>(thrd_tile_input[i].data.elt[j]) * scale_data))));
+        } else {
+          scaled_elt =
+              static_cast<OType>(static_cast<CType>(thrd_tile_input[i].data.elt[j]) * scale_data);
         }
         tmp_output_c.data.elt[j] = scaled_elt;
         // Step 4: do transpose within thread tile
@@ -459,7 +836,7 @@ __global__ void __launch_bounds__(THREADS_PER_BLOCK) block_scaled_cast_transpose
 
     if constexpr (kReturnTranspose) {
       const size_t block_tile_t_start_idx =
-          tile_id_x * BLOCK_TILE_DIM * num_rows + tile_id_y * BLOCK_TILE_DIM;
+          tile_id_x * BLOCK_TILE_DIM64 * num_rows + tile_id_y * BLOCK_TILE_DIM64;
       const size_t warp_tile_t_start_idx =
           block_tile_t_start_idx +
           warp_id_in_block_x * THREAD_TILE_DIM_X * NUM_THREADS_X_IN_WARP * num_rows +
@@ -540,8 +917,9 @@ void quantize_transpose_square_blockwise(const SimpleTensor& input, SimpleTensor
     scale_t_stride_y = scale_inv_t.shape[1];
   }
 
-  const size_t num_blocks_x = DIVUP(row_length, BLOCK_TILE_DIM);
-  const size_t num_blocks_y = DIVUP(num_rows, BLOCK_TILE_DIM);
+  const size_t block_len = blockwise_fp8_block_len();
+  const size_t num_blocks_x = DIVUP(row_length, block_len);
+  const size_t num_blocks_y = DIVUP(num_rows, block_len);
 
   TRANSFORMER_ENGINE_TYPE_SWITCH_INPUT(
       input.dtype, InputType,
@@ -553,8 +931,7 @@ void quantize_transpose_square_blockwise(const SimpleTensor& input, SimpleTensor
               return_transpose, kReturnTranspose,
 
               dim3 grid(num_blocks_x, num_blocks_y, 1);
-              const bool full_tile =
-                  row_length % BLOCK_TILE_DIM == 0 && num_rows % BLOCK_TILE_DIM == 0;
+              const bool full_tile = row_length % block_len == 0 && num_rows % block_len == 0;
 
               if (full_tile) {
 #ifndef __HIP_PLATFORM_AMD__
@@ -573,27 +950,64 @@ void quantize_transpose_square_blockwise(const SimpleTensor& input, SimpleTensor
                         scale_stride_x, scale_stride_y, scale_t_stride_x, scale_t_stride_y, epsilon,
                         tensor_map_output_trans, pow_2_scale);
 #else
-                block_scaled_cast_transpose_kernel<kReturnTranspose, float, InputType, OutputType>
-                    <<<grid, THREADS_PER_BLOCK, 0, stream>>>(
-                        reinterpret_cast<const InputType*>(input.dptr),
-                        reinterpret_cast<OutputType*>(output.dptr),
-                        reinterpret_cast<OutputType*>(output_t.dptr),
-                        reinterpret_cast<float*>(scale_inv.dptr),
-                        reinterpret_cast<float*>(scale_inv_t.dptr), row_length, num_rows,
-                        scale_stride_x, scale_stride_y, scale_t_stride_x, scale_t_stride_y, epsilon,
-                        pow_2_scale);
+                while (true) {
+                  if (128 == block_len) {
+                    block_scaled_cast_transpose_kernel<kReturnTranspose, float, InputType,
+                                                       OutputType>
+                        <<<grid, THREADS_PER_BLOCK, 0, stream>>>(
+                            reinterpret_cast<const InputType*>(input.dptr),
+                            reinterpret_cast<OutputType*>(output.dptr),
+                            reinterpret_cast<OutputType*>(output_t.dptr),
+                            reinterpret_cast<float*>(scale_inv.dptr),
+                            reinterpret_cast<float*>(scale_inv_t.dptr), row_length, num_rows,
+                            scale_stride_x, scale_stride_y, scale_t_stride_x, scale_t_stride_y,
+                            epsilon, pow_2_scale);
+                    break;
+                  }
+                  if (64 == block_len) {
+                    block_scaled_block_len64_cast_transpose_kernel<kReturnTranspose, float,
+                                                                   InputType, OutputType>
+                        <<<grid, THREADS_PER_BLOCK64, 0, stream>>>(
+                            reinterpret_cast<const InputType*>(input.dptr),
+                            reinterpret_cast<OutputType*>(output.dptr),
+                            reinterpret_cast<OutputType*>(output_t.dptr),
+                            reinterpret_cast<float*>(scale_inv.dptr),
+                            reinterpret_cast<float*>(scale_inv_t.dptr), row_length, num_rows,
+                            scale_stride_x, scale_stride_y, scale_t_stride_x, scale_t_stride_y,
+                            epsilon, pow_2_scale);
+                    break;
+                  }
+                }
 #endif
               } else {
-                block_scaled_cast_transpose_kernel_notaligned<kReturnTranspose, float, InputType,
-                                                              OutputType>
-                    <<<grid, THREADS_PER_BLOCK, 0, stream>>>(
-                        reinterpret_cast<const InputType*>(input.dptr),
-                        reinterpret_cast<OutputType*>(output.dptr),
-                        reinterpret_cast<OutputType*>(output_t.dptr),
-                        reinterpret_cast<float*>(scale_inv.dptr),
-                        reinterpret_cast<float*>(scale_inv_t.dptr), row_length, num_rows,
-                        scale_stride_x, scale_stride_y, scale_t_stride_x, scale_t_stride_y, epsilon,
-                        pow_2_scale);
+                while (true) {
+                  if (128 == block_len) {
+                    block_scaled_cast_transpose_kernel_notaligned<kReturnTranspose, float,
+                                                                  InputType, OutputType>
+                        <<<grid, THREADS_PER_BLOCK, 0, stream>>>(
+                            reinterpret_cast<const InputType*>(input.dptr),
+                            reinterpret_cast<OutputType*>(output.dptr),
+                            reinterpret_cast<OutputType*>(output_t.dptr),
+                            reinterpret_cast<float*>(scale_inv.dptr),
+                            reinterpret_cast<float*>(scale_inv_t.dptr), row_length, num_rows,
+                            scale_stride_x, scale_stride_y, scale_t_stride_x, scale_t_stride_y,
+                            epsilon, pow_2_scale);
+                    break;
+                  }
+                  if (64 == block_len) {
+                    block_scaled_block_len64_cast_transpose_kernel_notaligned<
+                        kReturnTranspose, float, InputType, OutputType>
+                        <<<grid, THREADS_PER_BLOCK64, 0, stream>>>(
+                            reinterpret_cast<const InputType*>(input.dptr),
+                            reinterpret_cast<OutputType*>(output.dptr),
+                            reinterpret_cast<OutputType*>(output_t.dptr),
+                            reinterpret_cast<float*>(scale_inv.dptr),
+                            reinterpret_cast<float*>(scale_inv_t.dptr), row_length, num_rows,
+                            scale_stride_x, scale_stride_y, scale_t_stride_x, scale_t_stride_y,
+                            epsilon, pow_2_scale);
+                    break;
+                  }
+                }
               }  // full-tile
               )  // return_transpose
           )      // OutputType

transformer_engine/common/transpose/quantize_transpose_vector_blockwise.cu

@@ -131,6 +131,7 @@ Step 3: Transpose, cast and store to output_t
 constexpr size_t kThreadsPerWarp = 32;
 
 // Hyperparameters for performance tuning
+constexpr int kTileDim64 = 64;
 constexpr int kTileDim = 128;  // Fixed to 128 beacause we are using 1x128 and 128x1 quantization
 constexpr int kNVecIn = 8;     // The number of elements each LDG touches
 constexpr int kNVecOut = 16;   // The number of elements each STG touches
@@ -148,6 +149,15 @@ constexpr int kNumThreadsStore = kTileDim / kNVecOut;
 static_assert(kNumThreadsLoad <= kThreadsPerWarp, "kNumThreadsLoad must be <= kThreadsPerWarp");
 static_assert(kNumThreadsStore <= kThreadsPerWarp, "kNumThreadsStore must be <= kThreadsPerWarp");
 
+constexpr int kSMemRow64 = kTileDim64;
+constexpr int kSMemCol64 = (kTileDim64 / kNVecSMem) + 1;
+constexpr int kSMemSize64 = kSMemRow64 * kSMemCol64 * kNVecSMem;
+constexpr int kNumThreadsLoad64 = kTileDim64 / kNVecIn;
+constexpr int kNumThreadsStore64 = kTileDim64 / kNVecOut;
+static_assert(kNumThreadsLoad64 <= kThreadsPerWarp, "kNumThreadsLoad64 must be <= kThreadsPerWarp");
+static_assert(kNumThreadsStore64 <= kThreadsPerWarp,
+              "kNumThreadsStore64 must be <= kThreadsPerWarp");
+
 template <bool kAligned, typename CType, typename IType, typename OType>
 __global__ void __launch_bounds__(kThreadsPerBlock) block_scaled_1d_cast_transpose_kernel(
     const IType* const input, OType* const output_c, OType* const output_t,
@@ -423,6 +433,290 @@ __global__ void __launch_bounds__(kThreadsPerBlock) block_scaled_1d_cast_transpo
   }
 }
 
+template <bool kAligned, typename CType, typename IType, typename OType>
+__global__ void __launch_bounds__(kThreadsPerBlock)
+    block_scaled_block_len64_1d_cast_transpose_kernel(
+        const IType* const input, OType* const output_c, OType* const output_t,
+        CType* const tile_scales_inv_c, CType* const tile_scales_inv_t, const size_t row_length,
+        const size_t num_rows, const size_t scale_stride_x, const size_t scale_stride_y,
+        const size_t scale_t_stride_x, const size_t scale_t_stride_y, const float epsilon,
+        FP8BlockwiseRowwiseOption rowwise_option, FP8BlockwiseColumnwiseOption columnwise_option,
+        const bool pow_2_scaling) {
+  bool return_rowwise = rowwise_option == FP8BlockwiseRowwiseOption::ROWWISE;
+  bool return_columnwise_transpose =
+      columnwise_option == FP8BlockwiseColumnwiseOption::COLUMNWISE_TRANSPOSE;
+
+  using SMemVec = Vec<IType, kNVecSMem>;
+  using OVec = Vec<OType, kNVecOut>;
+  union IVec {
+    Vec<IType, kNVecIn> input_type;
+    Vec<SMemVec, kNVecIn / kNVecSMem> smem_type;
+  };
+
+  extern __shared__ char smem_base[];
+  SMemVec* smem = reinterpret_cast<SMemVec*>(&smem_base[0]);
+
+  // Step 1: Load input to shared memory
+  {
+    constexpr int r_stride =
+        kThreadsPerBlock / kNumThreadsLoad64;  // stride in rows of shared memory
+    constexpr int num_iterations = kTileDim64 / r_stride;
+    const int c_s =
+        (threadIdx.x % kNumThreadsLoad64) * (kNVecIn / kNVecSMem);  // Column in shared memory
+    int r_s = threadIdx.x / kNumThreadsLoad64;                      // Row in shared memory
+    const size_t c_g =
+        static_cast<size_t>(blockIdx.x) * kTileDim64 + c_s * kNVecSMem;  // Column in global memory
+    size_t r_g = static_cast<size_t>(blockIdx.y) * kTileDim64 + r_s;     // Row in global memory
+    const size_t stride_g = static_cast<size_t>(r_stride) * row_length;  // Stride in global memory
+    const size_t num_ele = c_g < row_length ? min(static_cast<size_t>(kNVecIn), row_length - c_g)
+                                            : 0;            // For not aligned case
+    const IType* input_g = &input[r_g * row_length + c_g];  // Input address in global memory
+#pragma unroll
+    for (int iter = 0; iter < num_iterations; ++iter) {
+      IVec input_vec;
+      // Step 1.1: Load from global memory (input) to registers
+      if constexpr (kAligned) {
+        input_vec.input_type.load_from(input_g);
+      } else {
+        if (r_g < num_rows) {
+          input_vec.input_type.load_from_elts(input_g, 0, num_ele);
+        } else {
+          input_vec.input_type.clear();
+        }
+      }
+      // Step 1.2: Write to shared memory
+#pragma unroll
+      for (int i = 0; i < kNVecIn / kNVecSMem; ++i) {
+        int c = c_s + i;
+        int r = r_s;
+        smem[r * kSMemCol64 + c] = input_vec.smem_type.data.elt[i];
+      }
+      // Step 1.3: Update input address, row index of shared memory, (and row index of global memory for not aligned case)
+      input_g += stride_g;
+      r_s += r_stride;
+      if constexpr (!kAligned) {
+        r_g += r_stride;
+      }
+    }
+  }
+
+  __syncthreads();
+
+  // Step 2: Cast and store to output_c
+  if (return_rowwise) {
+    constexpr int r_stride =
+        kThreadsPerBlock / kNumThreadsStore64;  // stride in rows of shared memory
+    constexpr int num_iterations = kTileDim64 / r_stride;
+    const int c_s =
+        (threadIdx.x % kNumThreadsStore64) * (kNVecOut / kNVecSMem);  // Column in shared memory
+    int r_s = threadIdx.x / kNumThreadsStore64;                       // Row in shared memory
+    const size_t c_g =
+        static_cast<size_t>(blockIdx.x) * kTileDim64 + c_s * kNVecSMem;  // Column in global memory
+    size_t r_g = static_cast<size_t>(blockIdx.y) * kTileDim64 + r_s;     // Row in global memory
+    const size_t stride_g = static_cast<size_t>(r_stride) * row_length;  // Stride in global memory
+    const size_t num_ele = c_g < row_length ? min(static_cast<size_t>(kNVecOut), row_length - c_g)
+                                            : 0;          // For not aligned case
+    OType* output_g = &output_c[r_g * row_length + c_g];  // Output address in global memory
+    // Each kNumThreadsStore threads form a warp process one row, we need to find the lane id of
+    // the first thread to do the reduction.
+    const unsigned src_lane =
+        (threadIdx.x % kThreadsPerWarp) / kNumThreadsStore64 * kNumThreadsStore64;
+    // This mask represents which threads should do the reduction together.
+    const unsigned mask = ((1 << kNumThreadsStore64) - 1) << src_lane;
+    const bool is_src_lane = (threadIdx.x % kNumThreadsStore64) == 0;
+#pragma unroll
+    for (int iter = 0; iter < num_iterations; ++iter) {
+      SMemVec smem_vec[kNVecOut / kNVecSMem];
+      // Step 2.1: Load from shared memory to registers
+#pragma unroll
+      for (int i = 0; i < kNVecOut / kNVecSMem; ++i) {
+        int c = c_s + i;
+        int r = r_s;
+        smem_vec[i] = smem[r * kSMemCol64 + c];
+      }
+      // Step 2.2: Compute local amax
+      CType amax = 0;
+#pragma unroll
+      for (int i = 0; i < kNVecOut / kNVecSMem; ++i) {
+#pragma unroll
+        for (int j = 0; j < kNVecSMem; ++j) {
+          __builtin_assume(amax >= 0);
+          amax = fmaxf(amax, fabsf(smem_vec[i].data.elt[j]));
+        }
+      }
+      // Step 2.3: Reduce amax
+#pragma unroll
+      for (int delta = kNumThreadsStore64 / 2; delta > 0; delta /= 2) {
+#ifdef __HIP_PLATFORM_AMD__
+        const float other_amax =
+            __shfl_down_sync((unsigned long long)(mask), amax, delta, kThreadsPerWarp);
+#else
+        const float other_amax = __shfl_down_sync(mask, amax, delta);
+#endif
+        __builtin_assume(amax >= 0);
+        __builtin_assume(other_amax >= 0);
+        amax = fmaxf(amax, other_amax);
+      }
+#ifdef __HIP_PLATFORM_AMD__
+      amax = __shfl_sync((unsigned long long)(mask), amax, src_lane, kThreadsPerWarp);
+#else
+      amax = __shfl_sync(mask, amax, src_lane);
+#endif
+      CType scale;
+      // Step 2.4: Compute scale
+      scale = compute_scale_from_types<IType, OType>(amax, epsilon, pow_2_scaling);
+      // Step 2.5: Write scale_inv
+      bool write_scale_inv = is_src_lane;
+      if constexpr (!kAligned) {
+        write_scale_inv &= (r_g < num_rows);
+      }
+      if (write_scale_inv) {
+        CType scale_inv = 1.0 / scale;
+        size_t row_idx = static_cast<size_t>(blockIdx.y) * kTileDim64 + r_s;
+        size_t col_idx = static_cast<size_t>(blockIdx.x);
+        tile_scales_inv_c[row_idx * scale_stride_y + col_idx * scale_stride_x] = scale_inv;
+      }
+      // Step 2.6: Quantize
+      OVec output_vec;
+#pragma unroll
+      for (int i = 0; i < kNVecOut / kNVecSMem; ++i) {
+#pragma unroll
+        for (int j = 0; j < kNVecSMem; ++j) {
+          if constexpr (std::is_same_v<OType, int8_t>) {
+            output_vec.data.elt[i * kNVecSMem + j] = static_cast<OType>(lroundf(fmaxf(
+                -127.0f, fminf(127.0f, static_cast<CType>(smem_vec[i].data.elt[j]) * scale))));
+          } else {
+            output_vec.data.elt[i * kNVecSMem + j] =
+                static_cast<OType>(static_cast<CType>(smem_vec[i].data.elt[j]) * scale);
+          }
+        }
+      }
+      // Step 2.7: Store output_c
+      if constexpr (kAligned) {
+        output_vec.store_to(output_g);
+      } else {
+        if (r_g < num_rows) {
+          output_vec.store_to_elts(output_g, 0, num_ele);
+        }
+      }
+      // Step 2.8: Update output address, row index of shared memory (and row index of global memory for not aligned case)
+      output_g += stride_g;
+      r_s += r_stride;
+      if constexpr (!kAligned) {
+        r_g += r_stride;
+      }
+    }
+  }
+
+  // Step 3: Transpose, cast and store to output_t
+  if (return_columnwise_transpose) {
+    constexpr int c_stride =
+        kThreadsPerBlock / kNumThreadsStore64;  // Stride in columns of shared memory
+    constexpr int total_smem_cols = kTileDim64 / kNVecSMem;
+    constexpr int num_iterations = (total_smem_cols + c_stride - 1) / c_stride;
+    const int r_s = (threadIdx.x % kNumThreadsStore64) * kNVecOut;  // Row in shared memory
+    int c_s = threadIdx.x / kNumThreadsStore64;                     // Column in shared memory
+    size_t r_g =
+        static_cast<size_t>(blockIdx.x) * kTileDim64 + c_s * kNVecSMem;  // Row in global memory
+    const size_t c_g =
+        static_cast<size_t>(blockIdx.y) * kTileDim64 + r_s;  // Column in global memory
+    const size_t stride_g =
+        static_cast<size_t>(c_stride) * kNVecSMem * num_rows;  // Stride in global memory
+    const size_t num_ele = c_g < num_rows ? min(static_cast<size_t>(kNVecOut), num_rows - c_g)
+                                          : 0;          // For not aligned case
+    OType* output_g = &output_t[r_g * num_rows + c_g];  // Output address in global memory
+    // Each kNumThreadsStore threads form a warp process one row, we need to find the lane id of
+    // the first thread to do the reduction.
+    const unsigned src_lane =
+        (threadIdx.x % kThreadsPerWarp) / kNumThreadsStore64 * kNumThreadsStore64;
+    // This mask represents which threads should do the reduction together.
+    const unsigned mask = ((1 << kNumThreadsStore64) - 1) << src_lane;
+    const bool is_src_lane = (threadIdx.x % kNumThreadsStore64) == 0;
+#pragma unroll
+    for (int iter = 0; iter < num_iterations; ++iter) {
+      if (c_s < total_smem_cols) {
+        SMemVec smem_vec[kNVecOut];
+        // Step 3.1: Load from shared memory to registers
+#pragma unroll
+        for (int i = 0; i < kNVecOut; ++i) {
+          int r = r_s + i;
+          int c = c_s;
+          smem_vec[i] = smem[r * kSMemCol64 + c];
+        }
+#pragma unroll
+        for (int smem_idx = 0; smem_idx < kNVecSMem; ++smem_idx) {
+          // Step 3.2: Compute local amax
+          CType amax = 0;
+#pragma unroll
+          for (int i = 0; i < kNVecOut; ++i) {
+            amax = fmaxf(amax, fabsf(smem_vec[i].data.elt[smem_idx]));
+          }
+          // Step 3.3: Reduce amax
+#pragma unroll
+          for (int delta = kNumThreadsStore64 / 2; delta > 0; delta /= 2) {
+#ifdef __HIP_PLATFORM_AMD__
+            const float other_amax =
+                __shfl_down_sync((unsigned long long)(mask), amax, delta, kThreadsPerWarp);
+#else
+            const float other_amax = __shfl_down_sync(mask, amax, delta);
+#endif
+            __builtin_assume(amax >= 0);
+            __builtin_assume(other_amax >= 0);
+            amax = fmaxf(amax, other_amax);
+          }
+#ifdef __HIP_PLATFORM_AMD__
+          amax = __shfl_sync((unsigned long long)(mask), amax, src_lane, kThreadsPerWarp);
+#else
+          amax = __shfl_sync(mask, amax, src_lane);
+#endif
+          // Step 3.4: Compute scale
+          CType scale;
+          scale = compute_scale_from_types<IType, OType>(amax, epsilon, pow_2_scaling);
+          // Step 3.5: Write scale_inv_t
+          bool write_scale_inv = is_src_lane;
+          if constexpr (!kAligned) {
+            write_scale_inv &= (r_g + smem_idx < row_length);
+          }
+          if (write_scale_inv) {
+            CType scale_inv = 1.0 / scale;
+            size_t row_idx =
+                static_cast<size_t>(blockIdx.x) * kTileDim64 + c_s * kNVecSMem + smem_idx;
+            size_t col_idx = static_cast<size_t>(blockIdx.y);
+            tile_scales_inv_t[row_idx * scale_t_stride_y + col_idx * scale_t_stride_x] = scale_inv;
+          }
+          // Step 3.6: Quantize
+          OVec output_vec;
+#pragma unroll
+          for (int i = 0; i < kNVecOut; ++i) {
+            if constexpr (std::is_same_v<OType, int8_t>) {
+              output_vec.data.elt[i] = static_cast<OType>(lroundf(fmaxf(
+                  -127.0f,
+                  fminf(127.0f, static_cast<CType>(smem_vec[i].data.elt[smem_idx]) * scale))));
+            } else {
+              output_vec.data.elt[i] =
+                  static_cast<OType>(static_cast<CType>(smem_vec[i].data.elt[smem_idx]) * scale);
+            }
+          }
+          // Step 3.7: Store output_t
+          if constexpr (kAligned) {
+            output_vec.store_to(output_g + smem_idx * num_rows);
+          } else {
+            if (r_g + smem_idx < row_length) {
+              output_vec.store_to_elts(output_g + smem_idx * num_rows, 0, num_ele);
+            }
+          }
+        }
+      }
+      // Step 3.8: Update output address, column index of shared memory (and row index of global memory for not aligned case)
+      output_g += stride_g;
+      c_s += c_stride;
+      if constexpr (!kAligned) {
+        r_g += c_stride * kNVecSMem;
+      }
+    }
+  }
+}
+
 #ifdef __HIP_PLATFORM_AMD__
 constexpr int kFP32SMemCol = kTileDim / kNVecSMem;
 constexpr int kFP32SMemSize = kSMemRow * kFP32SMemCol * kNVecSMem;
@@ -771,8 +1065,9 @@ void quantize_transpose_vector_blockwise(const SimpleTensor& input, SimpleTensor
     scale_t_stride_y = 1;
   }
 
-  const size_t num_blocks_x = DIVUP(row_length, (size_t)kTileDim);
-  const size_t num_blocks_y = DIVUP(num_rows, (size_t)kTileDim);
+  const size_t block_len = blockwise_fp8_block_len();
+  const size_t num_blocks_x = DIVUP(row_length, (size_t)block_len);
+  const size_t num_blocks_y = DIVUP(num_rows, (size_t)block_len);
 
   TRANSFORMER_ENGINE_TYPE_SWITCH_INPUT(
       input.dtype, InputType,
@@ -782,46 +1077,72 @@ void quantize_transpose_vector_blockwise(const SimpleTensor& input, SimpleTensor
 
           dim3 grid(num_blocks_x, num_blocks_y, 1);
 
-          const bool full_tile = row_length % kTileDim == 0 && num_rows % kTileDim == 0;
+          const bool full_tile = row_length % block_len == 0 && num_rows % block_len == 0;
 
           TRANSFORMER_ENGINE_SWITCH_CONDITION(
               full_tile, kAligned,
 
 #ifdef __HIP_PLATFORM_AMD__
-              if constexpr (std::is_same_v<InputType, float>) {
-                size_t smem_bytes = kFP32SMemSize * sizeof(InputType);
-                if (smem_bytes >= 48 * 1024) {
-                  cudaError_t err =
-                      cudaFuncSetAttribute((const void*)&block_scaled_1d_cast_transpose_kernel_fp32<
-                                               kAligned, float, InputType, OutputType>,
-                                           cudaFuncAttributeMaxDynamicSharedMemorySize, smem_bytes);
+              while (true) {
+                if (128 == block_len) {
+                  if constexpr (std::is_same_v<InputType, float>) {
+                    size_t smem_bytes = kFP32SMemSize * sizeof(InputType);
+                    if (smem_bytes >= 48 * 1024) {
+                      cudaError_t err = cudaFuncSetAttribute(
+                          (const void*)&block_scaled_1d_cast_transpose_kernel_fp32<
+                              kAligned, float, InputType, OutputType>,
+                          cudaFuncAttributeMaxDynamicSharedMemorySize, smem_bytes);
+                    }
+                    block_scaled_1d_cast_transpose_kernel_fp32<kAligned, float, InputType,
+                                                               OutputType>
+                        <<<grid, kThreadsPerBlock, smem_bytes, stream>>>(
+                            reinterpret_cast<const InputType*>(input.dptr),
+                            reinterpret_cast<OutputType*>(output.dptr),
+                            reinterpret_cast<OutputType*>(output_t.dptr),
+                            reinterpret_cast<float*>(scale_inv.dptr),
+                            reinterpret_cast<float*>(scale_inv_t.dptr), row_length, num_rows,
+                            scale_stride_x, scale_stride_y, scale_t_stride_x, scale_t_stride_y,
+                            epsilon, rowwise_option, columnwise_option, pow2_scale);
+                  } else {
+                    size_t smem_bytes = kSMemSize * sizeof(InputType);
+                    if (smem_bytes >= 48 * 1024) {
+                      cudaError_t err = cudaFuncSetAttribute(
+                          (const void*)&block_scaled_1d_cast_transpose_kernel<
+                              kAligned, float, InputType, OutputType>,
+                          cudaFuncAttributeMaxDynamicSharedMemorySize, smem_bytes);
+                    }
+                    block_scaled_1d_cast_transpose_kernel<kAligned, float, InputType, OutputType>
+                        <<<grid, kThreadsPerBlock, smem_bytes, stream>>>(
+                            reinterpret_cast<const InputType*>(input.dptr),
+                            reinterpret_cast<OutputType*>(output.dptr),
+                            reinterpret_cast<OutputType*>(output_t.dptr),
+                            reinterpret_cast<float*>(scale_inv.dptr),
+                            reinterpret_cast<float*>(scale_inv_t.dptr), row_length, num_rows,
+                            scale_stride_x, scale_stride_y, scale_t_stride_x, scale_t_stride_y,
+                            epsilon, rowwise_option, columnwise_option, pow2_scale);
+                  }
+                  break;
                 }
-                block_scaled_1d_cast_transpose_kernel_fp32<kAligned, float, InputType, OutputType>
-                    <<<grid, kThreadsPerBlock, smem_bytes, stream>>>(
-                        reinterpret_cast<const InputType*>(input.dptr),
-                        reinterpret_cast<OutputType*>(output.dptr),
-                        reinterpret_cast<OutputType*>(output_t.dptr),
-                        reinterpret_cast<float*>(scale_inv.dptr),
-                        reinterpret_cast<float*>(scale_inv_t.dptr), row_length, num_rows,
-                        scale_stride_x, scale_stride_y, scale_t_stride_x, scale_t_stride_y, epsilon,
-                        rowwise_option, columnwise_option, pow2_scale);
-              } else {
-                size_t smem_bytes = kSMemSize * sizeof(InputType);
-                if (smem_bytes >= 48 * 1024) {
-                  cudaError_t err = cudaFuncSetAttribute(
-                      (const void*)&block_scaled_1d_cast_transpose_kernel<kAligned, float,
-                                                                          InputType, OutputType>,
-                      cudaFuncAttributeMaxDynamicSharedMemorySize, smem_bytes);
+                if (64 == block_len) {
+                  size_t smem_bytes = kSMemSize64 * sizeof(InputType);
+                  if (smem_bytes >= 48 * 1024) {
+                    cudaError_t err = cudaFuncSetAttribute(
+                        (const void*)&block_scaled_block_len64_1d_cast_transpose_kernel<
+                            kAligned, float, InputType, OutputType>,
+                        cudaFuncAttributeMaxDynamicSharedMemorySize, smem_bytes);
+                  }
+                  block_scaled_block_len64_1d_cast_transpose_kernel<kAligned, float, InputType,
+                                                                    OutputType>
+                      <<<grid, kThreadsPerBlock, smem_bytes, stream>>>(
+                          reinterpret_cast<const InputType*>(input.dptr),
+                          reinterpret_cast<OutputType*>(output.dptr),
+                          reinterpret_cast<OutputType*>(output_t.dptr),
+                          reinterpret_cast<float*>(scale_inv.dptr),
+                          reinterpret_cast<float*>(scale_inv_t.dptr), row_length, num_rows,
+                          scale_stride_x, scale_stride_y, scale_t_stride_x, scale_t_stride_y,
+                          epsilon, rowwise_option, columnwise_option, pow2_scale);
+                  break;
                 }
-                block_scaled_1d_cast_transpose_kernel<kAligned, float, InputType, OutputType>
-                    <<<grid, kThreadsPerBlock, smem_bytes, stream>>>(
-                        reinterpret_cast<const InputType*>(input.dptr),
-                        reinterpret_cast<OutputType*>(output.dptr),
-                        reinterpret_cast<OutputType*>(output_t.dptr),
-                        reinterpret_cast<float*>(scale_inv.dptr),
-                        reinterpret_cast<float*>(scale_inv_t.dptr), row_length, num_rows,
-                        scale_stride_x, scale_stride_y, scale_t_stride_x, scale_t_stride_y, epsilon,
-                        rowwise_option, columnwise_option, pow2_scale);
               }
 #else
               size_t smem_bytes = kSMemSize * sizeof(InputType);

transformer_engine/pytorch/cpp_extensions/gemm.py

@@ -15,6 +15,7 @@ from transformer_engine.pytorch.triton.blockwise_int8_gemm_nt_wgrad import w8a8_
 from ..tensor.quantized_tensor import Quantizer
 from ..tensor._internal.float8_blockwise_tensor_base import Float8BlockwiseQTensorBase
 from ...debug.pytorch.debug_quantization import DebugQuantizer
+from transformer_engine.pytorch.fp8 import blockwise_fp8_block_len
 
 int8_simulation_fp8 = bool(int(os.getenv("NVTE_INT8_SIM_FP8", "0")))
 __all__ = [
@@ -76,7 +77,7 @@ def general_gemm(
             ref_scales_w = A._rowwise_scale_inv
         
             y, _ = w8a8_block_int8_matmul(
-                qx_data, qw_data, ref_scales_x, ref_scales_w, [128, 128],
+                qx_data, qw_data, ref_scales_x, ref_scales_w, [blockwise_fp8_block_len, blockwise_fp8_block_len],
                 output_dtype=out_dtype
             )
             return y, None, None, None
@@ -92,7 +93,7 @@ def general_gemm(
             ref_scales_w = A._columnwise_scale_inv
         
             y, _ = w8a8_block_int8_matmul(
-                qdout_data, qw_data, ref_scales_dout, ref_scales_w, [128, 128],
+                qdout_data, qw_data, ref_scales_dout, ref_scales_w, [blockwise_fp8_block_len, blockwise_fp8_block_len],
                 output_dtype=out_dtype
             )
             return y, None, None, None
@@ -108,7 +109,7 @@ def general_gemm(
             ref_scales_x = A._columnwise_scale_inv
         
             out, _ = w8a8_block_int8_matmul_wgrad(
-                qdout_data, qx_data, ref_scales_dout, ref_scales_x, out, accumulate, [128, 128],
+                qdout_data, qx_data, ref_scales_dout, ref_scales_x, out, accumulate, [blockwise_fp8_block_len, blockwise_fp8_block_len],
                 output_dtype=out_dtype
             )
             return out, None, None, None
@@ -243,7 +244,7 @@ def general_grouped_gemm(
             seq_len = sum(m_splits) // num_gemms
 
             out[0] = w8a8_block_int8_matmul_batched(
-                qx_data, qw_data, ref_scales_x, ref_scales_w, out[0].view(num_gemms, seq_len, out[0].size(-1)), [128, 128],
+                qx_data, qw_data, ref_scales_x, ref_scales_w, out[0].view(num_gemms, seq_len, out[0].size(-1)), [blockwise_fp8_block_len, blockwise_fp8_block_len],
                 output_dtype=out_dtype
             )
             return out, bias, gelu_input
@@ -262,7 +263,7 @@ def general_grouped_gemm(
             seq_len = sum(m_splits) // num_gemms
         
             out[0] = w8a8_block_int8_matmul_batched(
-                qdout_data, qw_data, ref_scales_dout, ref_scales_w, out[0].view(num_gemms, seq_len, out[0].size(-1)), [128, 128],
+                qdout_data, qw_data, ref_scales_dout, ref_scales_w, out[0].view(num_gemms, seq_len, out[0].size(-1)), [blockwise_fp8_block_len, blockwise_fp8_block_len],
                 output_dtype=out_dtype
             )
             return out, bias, gelu_input
@@ -278,7 +279,7 @@ def general_grouped_gemm(
             ref_scales_x = [a._columnwise_scale_inv for a in A]
         
             out = w8a8_block_int8_matmul_wgrad_batched_native(
-                qdout_data, qx_data, ref_scales_dout, ref_scales_x, out, accumulate, [128, 128],
+                qdout_data, qx_data, ref_scales_dout, ref_scales_x, out, accumulate, [blockwise_fp8_block_len, blockwise_fp8_block_len],
                 output_dtype=out_dtype
             )
             return out, bias, gelu_input

transformer_engine/pytorch/csrc/common.h

@@ -48,6 +48,8 @@
 #include <cassert>
 #include <cstring>
 #include <iostream>
+#include <string>
+#include <sstream>
 #include <memory>
 #include <torch/csrc/distributed/c10d/ProcessGroup.hpp>
 #include <vector>
@@ -60,6 +62,18 @@ namespace transformer_engine::pytorch {
 // in python we have: dist_group_type = torch.distributed.ProcessGroup
 using dist_group_type = c10d::ProcessGroup;
 
+inline int blockwise_fp8_block_len() {
+  const char *env = std::getenv("NVTE_BLOCKWISE_FP8_BLOCK_LEN");
+  if (env == nullptr || env[0] == '\0') {
+    return 128;
+  }
+  int value;
+  std::istringstream iss(env);
+  iss >> value;
+  NVTE_CHECK(iss, "Invalid environment variable value");
+  return value;
+}
+
 // Each tensor here is shape (N, ) holding all scaling
 // data for a single FP8 block, e.g. LayerNormLinear
 class FP8TensorMeta {

transformer_engine/pytorch/csrc/extensions/fp8_block_scaling_partial_cast.cpp

@@ -10,7 +10,7 @@ namespace transformer_engine::pytorch {
 
 void fp8_block_scaling_compute_partial_amax(const at::Tensor &tensor, at::Tensor amax, size_t h,
                                             size_t w, size_t start_offset, size_t block_len) {
-  TORCH_CHECK(block_len == 128, "Currently only block_len = 128 is supported");
+  TORCH_CHECK(block_len == 128 || block_len == 64, "Currently only block_len = 128 or 64 is supported");
   TORCH_CHECK(amax.dim() == 2, "amax must be a 2D tensor");
   TORCH_CHECK(amax.scalar_type() == at::ScalarType::Float, "amax must be a float tensor");
   TORCH_CHECK(tensor.scalar_type() == at::ScalarType::Float ||
@@ -28,7 +28,7 @@ void fp8_block_scaling_compute_partial_amax(const at::Tensor &tensor, at::Tensor
 void fp8_block_scaling_partial_cast(const at::Tensor &inp, at::Tensor out, const at::Tensor &scale,
                                     size_t h, size_t w, size_t start_offset, size_t block_len,
                                     const transformer_engine::DType out_dtype) {
-  TORCH_CHECK(block_len == 128, "Currently only block_len = 128 is supported");
+  TORCH_CHECK(block_len == 128 || block_len == 64, "Currently only block_len = 128 or 64 is supported");
   TORCH_CHECK(scale.dim() == 2, "scale must be a 2D tensor");
   TORCH_CHECK(scale.scalar_type() == at::ScalarType::Float, "scale must be a float tensor");
   TORCH_CHECK(

transformer_engine/pytorch/csrc/quantizer.cpp

@@ -297,7 +297,7 @@ std::pair<TensorWrapper, py::object> Float8BlockQuantizer::create_tensor(
 
   size_t k_dim = torch_shape.size() == 0 ? 1u : torch_shape.back();
   size_t m_dim = numel / k_dim;
-  constexpr size_t kBlockLen = 128;
+  size_t kBlockLen = static_cast<size_t>(blockwise_fp8_block_len());
 
   if (rowwise_usage) {
     if (rowwise_data.has_value()) {

transformer_engine/pytorch/distributed.py

@@ -1018,7 +1018,7 @@ def _all_gather_fp8_blockwise(
     # Check that quantizer is valid
     if quantizer is not None and not isinstance(quantizer, Float8BlockQuantizer):
         raise ValueError(f"Got non-FP8 blockwise quantizer ({quantizer.__class__.__name__})")
-    if not (quantizer.block_scaling_dim == 1 and quantizer.block_len == 128):
+    if not (quantizer.block_scaling_dim == 1 and (quantizer.block_len == 128 or quantizer.block_len == 64)):
         raise NotImplementedError("Only 1D blockwise quantization is supported for allgather")
 
     # Output tensor dims

transformer_engine/pytorch/fp8.py

@@ -28,6 +28,7 @@ from .utils import get_device_compute_capability
 from .jit import jit_fuser
 from torch.utils.cpp_extension import IS_HIP_EXTENSION
 int8_simulation_fp8 = bool(int(os.getenv("NVTE_INT8_SIM_FP8", "0")))
+blockwise_fp8_block_len = int(os.getenv("NVTE_BLOCKWISE_FP8_BLOCK_LEN", "128"))
 
 __all__ = ["fp8_autocast", "fp8_model_init"]
 

transformer_engine/pytorch/tensor/_internal/float8_blockwise_tensor_base.py

@@ -11,6 +11,7 @@ import torch
 
 import transformer_engine_torch as tex
 from transformer_engine_torch import DType as TE_DType
+from transformer_engine.pytorch.fp8 import blockwise_fp8_block_len
 
 from ..quantized_tensor import QuantizedTensorBase
 
@@ -125,7 +126,7 @@ class Float8BlockwiseQTensorBase(QuantizedTensorBase):
         return torch.permute(columnwise_dq, tuple(permute_dims)).contiguous()
 
     def _dequantize_vectorwise(self, *, dtype: torch.dtype = torch.float32) -> torch.Tensor:
-        block_len = 128
+        block_len = blockwise_fp8_block_len
 
         q_M, q_K = 1, 1
         if self._rowwise_data is not None:
@@ -178,7 +179,7 @@ class Float8BlockwiseQTensorBase(QuantizedTensorBase):
         """
         Construct plain PyTorch tensor from Float8BlockwiseQTensor
         """
-        block_len = 128
+        block_len = blockwise_fp8_block_len
         if not self._is_2D_scaled:
             return self._dequantize_vectorwise(dtype=dtype)
 

transformer_engine/pytorch/tensor/float8_blockwise_tensor.py

@@ -14,6 +14,7 @@ from transformer_engine_torch import DType as TE_DType
 from ._internal.float8_blockwise_tensor_base import Float8BlockwiseQTensorBase
 from .quantized_tensor import QuantizedTensor, Quantizer, _IdentityFunc
 from ..utils import devices_match, round_up_to_nearest_multiple
+from transformer_engine.pytorch.fp8 import blockwise_fp8_block_len
 
 aten = torch.ops.aten
 
@@ -46,7 +47,7 @@ class Float8BlockQuantizer(Quantizer):
     ) -> None:
         super().__init__(rowwise=rowwise, columnwise=columnwise)
         self.dtype = tex.DType.kInt8 if int8_simulation_fp8 else fp8_dtype
-        self.block_len = 128
+        self.block_len = blockwise_fp8_block_len
         self.force_pow_2_scales = force_pow_2_scales
         self.amax_epsilon = amax_epsilon
         self.block_scaling_dim = block_scaling_dim