minimax_reduce_rms_kernel.h

/*
 * Copyright (c) 2026, NVIDIA CORPORATION.  All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <cuda_bf16.h>
#include <cuda_fp16.h>

#include <torch/types.h>

namespace vllm {
namespace tensorrt_llm {

template <typename DType>
struct ElemsPerAccess;

template <>
struct ElemsPerAccess<half> {
  static constexpr int value = 8;
  using vec_type = float4;
};

template <>
struct ElemsPerAccess<nv_bfloat16> {
  static constexpr int value = 8;
  using vec_type = float4;
};

template <>
struct ElemsPerAccess<float> {
  static constexpr int value = 4;
  using vec_type = float4;
};

template <typename DType>
static constexpr int kElemsPerAccess = ElemsPerAccess<DType>::value;

struct MiniMaxReduceRMSParams {
  int nranks{};
  int rank{};
  at::ScalarType dtype{at::ScalarType::Undefined};
  int size_q{};
  int hidden_dim{};
  int size_k{};
  int hidden_dim_k{};
  int stride_q{};  // row stride for q input (elements); when > hidden_dim,
                   // q is part of a wider qkv tensor
  int stride_k{};  // row stride for k input (elements); when > hidden_dim_k,
                   // k is part of a wider qkv tensor
  int stride_q_out{};  // row stride for q output (elements); 0 = contiguous
  int stride_k_out{};  // row stride for k output (elements); 0 = contiguous
  void** workspace{};
  void* allreduce_in{};
  void* rms_norm_out{};
  void* rms_gamma{};
  void* allreduce_in_k{};
  void* rms_norm_out_k{};
  void* rms_gamma_k{};
  float rms_eps{};
  cudaStream_t stream{};
};

void minimax_reduce_rms_op(MiniMaxReduceRMSParams const& params);

}  // namespace tensorrt_llm
}  // namespace vllm