speed up nvte_multi_padding / nvte_multi_unpadding

transformer_engine/common/util/padding.cu

@@ -1,4 +1,6 @@
 /*************************************************************************
+* This file was modified for portability to AMDGPU
+ * Copyright (c) 2026, Advanced Micro Devices, Inc. All rights reserved.
  * Copyright (c) 2022-2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
  *
  * See LICENSE for license information.
@@ -13,13 +15,42 @@
 
 #include "../common.h"
 #include "../utils.cuh"
+#ifdef __HIP_PLATFORM_AMD__
+#include "rocm_device_utils.cuh"  // for rocm_upper_bound(), NTVec
+#endif
 
 namespace transformer_engine {
 
 namespace {
 
+#ifdef __HIP_PLATFORM_AMD__
+// Non-temporal store helper: uses NT store for full aligned vectors,
+// falls back to element-wise for partial/unaligned cases.
+// Note: NT loads were also benchmarked but hurt performance.
+template <uint32_t nvec, typename Type>
+__device__ __forceinline__ void nt_store_to_elts(const Vec<Type, nvec>& v,
+                                                 Type* ptr, int count) {
+  constexpr size_t BYTES = nvec * sizeof(Type);
+  if (count == nvec && reinterpret_cast<uint64_t>(ptr) % BYTES == 0) {
+    NTVec<Type, nvec> nt;
+#pragma unroll
+    for (int i = 0; i < nvec; i++) nt.val[i] = v.data.elt[i];
+    nt.nt_store(ptr);
+  } else {
+#pragma unroll
+    for (int i = 0; i < nvec; i++) {
+      if (i < count) ptr[i] = v.data.elt[i];
+    }
+  }
+}
+#endif
+
 // Parameters to tune
+#ifdef __HIP_PLATFORM_AMD__
+constexpr int n_warps_per_tile = 16;
+#else
 constexpr int n_warps_per_tile = 4;
+#endif
 constexpr int threads_per_block = THREADS_PER_WARP * n_warps_per_tile;
 constexpr int desired_load_store_size = 8;
 constexpr int kMaxTensorsPerKernel = 64;  // Args must be <4 KB
@@ -65,15 +96,22 @@ __global__ void __launch_bounds__(threads_per_block) multi_padding_kernel(MultiP
   constexpr int n_iterations = THREADS_PER_WARP / n_warps_per_tile;
 
   // Find tensor corresponding to block
+#ifdef __HIP_PLATFORM_AMD__
+  const int tensor_id = rocm_upper_bound(args.block_range, args.num_tensors, bid);
+#else
   int tensor_id = 0;
   while (args.block_range[tensor_id + 1] <= bid) {
     ++tensor_id;
   }
+#endif
   const Type* input = reinterpret_cast<const Type*>(args.input_list[tensor_id]);
   Type* output = reinterpret_cast<Type*>(args.output_list[tensor_id]);
   const int num_rows = args.num_rows_list[tensor_id];
   const int padded_num_rows = args.padded_num_rows_list[tensor_id];
   const int row_length = args.row_length_list[tensor_id];
+#ifdef __HIP_PLATFORM_AMD__
+  const bool inplace = (input == output);
+#endif
 
   // Find position of tile within tensor
   const int num_tiles_n = (row_length + tile_dim_n - 1) / tile_dim_n;
@@ -83,6 +121,36 @@ __global__ void __launch_bounds__(threads_per_block) multi_padding_kernel(MultiP
   const int tile_row = tile_id_m * tile_dim_m;
   const int tile_col = tile_id_n * tile_dim_n;
 
+#ifdef __HIP_PLATFORM_AMD__
+  // Process subtiles with vectorized loads/stores
+#pragma unroll
+  for (int iter = 0; iter < n_iterations; ++iter) {
+    const int i1 = tidy + iter * bdimy;
+    const int j1 = tidx;
+    const int col = tile_col + j1 * nvec;
+    const int remaining = row_length - col;
+    const int valid_cols = remaining > 0 ? min(remaining, nvec) : 0;
+#pragma unroll
+    for (int i2 = 0; i2 < nvec; ++i2) {
+      const int row = tile_row + i1 * nvec + i2;
+      if (row < num_rows) {
+        // Valid data row: skip copy when in-place
+        if (!inplace) {
+          const size_t offset = static_cast<size_t>(row) * row_length + col;
+          Vec v;
+          v.load_from_elts(input, offset, valid_cols);
+          nt_store_to_elts(v, output + offset, valid_cols);
+        }
+      } else if (row < padded_num_rows) {
+        // Padding row: fill with zeros
+        const size_t offset = static_cast<size_t>(row) * row_length + col;
+        Vec v;
+        v.clear();
+        nt_store_to_elts(v, output + offset, valid_cols);
+      }
+    }
+  }
+#else  // !__HIP_PLATFORM_AMD__
   // Load input and store to registers
   // Note: Each thread loads n_iterations subtiles, casts to output
   // type, and transposes in registers.
@@ -125,6 +193,7 @@ __global__ void __launch_bounds__(threads_per_block) multi_padding_kernel(MultiP
       }
     }
   }
+#endif  // __HIP_PLATFORM_AMD__
 }
 
 template <int nvec, typename Type>
@@ -150,14 +219,21 @@ __global__ void __launch_bounds__(threads_per_block) multi_unpadding_kernel(Mult
   constexpr int n_iterations = THREADS_PER_WARP / n_warps_per_tile;
 
   // Find tensor corresponding to block
+#ifdef __HIP_PLATFORM_AMD__
+  const int tensor_id = rocm_upper_bound(args.block_range, args.num_tensors, bid);
+#else
   int tensor_id = 0;
   while (args.block_range[tensor_id + 1] <= bid) {
     ++tensor_id;
   }
+#endif
   const Type* input = reinterpret_cast<const Type*>(args.input_list[tensor_id]);
   Type* output = reinterpret_cast<Type*>(args.output_list[tensor_id]);
   const int num_rows = args.num_rows_list[tensor_id];
   const int row_length = args.row_length_list[tensor_id];
+#ifdef __HIP_PLATFORM_AMD__
+  const bool inplace = (input == output);
+#endif
 
   // Find position of tile within tensor
   const int num_tiles_n = (row_length + tile_dim_n - 1) / tile_dim_n;
@@ -167,6 +243,27 @@ __global__ void __launch_bounds__(threads_per_block) multi_unpadding_kernel(Mult
   const int tile_row = tile_id_m * tile_dim_m;
   const int tile_col = tile_id_n * tile_dim_n;
 
+#ifdef __HIP_PLATFORM_AMD__
+  // Process subtiles with vectorized loads/stores
+#pragma unroll
+  for (int iter = 0; iter < n_iterations; ++iter) {
+    const int i1 = tidy + iter * bdimy;
+    const int j1 = tidx;
+    const int col = tile_col + j1 * nvec;
+    const int remaining = row_length - col;
+    const int valid_cols = remaining > 0 ? min(remaining, nvec) : 0;
+#pragma unroll
+    for (int i2 = 0; i2 < nvec; ++i2) {
+      const int row = tile_row + i1 * nvec + i2;
+      if (row < num_rows && !inplace) {
+        const size_t offset = static_cast<size_t>(row) * row_length + col;
+        Vec v;
+        v.load_from_elts(input, offset, valid_cols);
+        nt_store_to_elts(v, output + offset, valid_cols);
+      }
+    }
+  }
+#else  // !__HIP_PLATFORM_AMD__
   // Load input and store to registers
   // Note: Each thread loads n_iterations subtiles, casts to output
   // type, and transposes in registers.
@@ -202,6 +299,7 @@ __global__ void __launch_bounds__(threads_per_block) multi_unpadding_kernel(Mult
       }
     }
   }
+#endif  // __HIP_PLATFORM_AMD__
 }
 
 }  // namespace

transformer_engine/common/util/rocm_device_utils.cuh

@@ -118,6 +118,23 @@ __device__ __forceinline__ void rocm_atomicMaxFloat(float *addr, float val) {
     atomicMax(reinterpret_cast<int*>(addr), __float_as_int(val));
 }
 
+// Binary search on a sorted array.
+// Returns the largest index i in [0, n) such that arr[i] <= val.
+// Precondition: arr is sorted in non-decreasing order and arr[0] <= val.
+template <typename T>
+__device__ __forceinline__ int rocm_upper_bound(const T* arr, int n, T val) {
+  int lo = 0, hi = n - 1;
+  while (lo < hi) {
+    int mid = (lo + hi + 1) / 2;
+    if (arr[mid] <= val) {
+      lo = mid;
+    } else {
+      hi = mid - 1;
+    }
+  }
+  return lo;
+}
+
 template <int WARPS>
 __device__ __forceinline__ float rocm_block_reduce_max(float val, int warp_id) {
     __shared__ float staging[WARPS];