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paddlepaddle--paddle/paddle/phi/kernels/gpu/calc_reduced_attn_kernel.cu
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// Copyright (c) 2024 PaddlePaddle Authors. 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.
#include "paddle/phi/kernels/calc_reduced_attn_kernel.h"
#include "paddle/phi/core/kernel_registry.h"
#include "paddle/phi/core/tensor_utils.h"
#include "paddle/phi/kernels/funcs/math_function.h"
#include "paddle/phi/kernels/gpu/flash_attn_utils.h"
namespace phi {
#if defined(PADDLE_WITH_FLASHATTN) && !defined(PADDLE_WITH_HIP)
struct CalcReducedAttnScoresParams : public FlashAttnParamsBase {
bool return_softmax;
DenseTensor* softmax;
CalcReducedAttnScoresParams(const GPUContext& dev_ctx,
const int _batch_size,
const int64_t _max_seqlen_q,
const int64_t _max_seqlen_k,
const int _num_heads,
const int _num_heads_k,
const int _head_size,
const float _scale,
const DataType q_dtype)
: FlashAttnParamsBase(/*version=*/2,
/*is_fwd=*/true,
_batch_size,
_max_seqlen_q,
_max_seqlen_k,
_num_heads,
_num_heads_k,
_head_size,
_scale,
/*_causal=*/false,
q_dtype,
optional<DenseTensor>{},
optional<DenseTensor>{},
/*_unpadded_lse=*/false,
/*_total_q*/ 0) {}
};
#endif
template <typename T, typename Context>
void CalcReducedAttnScoresKernel(const Context& dev_ctx,
const DenseTensor& q,
const DenseTensor& k,
const DenseTensor& softmax_lse,
DenseTensor* reduced_scores) {
#if defined(PADDLE_WITH_FLASHATTN) && !defined(PADDLE_WITH_HIP)
PADDLE_ENFORCE_EQ(q.dims().size(),
4,
common::errors::InvalidArgument(
"calc_reduced_attention receive input with dim "
"[batch_size, seq_len, num_heads, head_dim]"));
PADDLE_ENFORCE_EQ(k.dims().size(),
4,
common::errors::InvalidArgument(
"calc_reduced_attention receive input with dim "
"[batch_size, seq_len, num_heads, head_dim]"));
if (!reduced_scores->IsInitialized())
dev_ctx.template Alloc<float>(reduced_scores);
funcs::SetConstant<Context, float> set_zero;
set_zero(dev_ctx, reduced_scores, 0.0f);
// q, k, v [batch_size, seq_len, num_heads, head_dim]
const int64_t batch_size = q.dims()[0];
const int64_t seqlen_q = q.dims()[1];
const int64_t num_heads = q.dims()[2];
const int64_t head_size = q.dims()[3];
const int64_t seqlen_k = k.dims()[1];
const int64_t num_heads_k = k.dims()[2];
const float softmax_scale = 1.0f / std::sqrt(head_size);
const float softmax_unscale = std::sqrt(head_size);
using Params = CalcReducedAttnScoresParams;
Params params = Params(dev_ctx,
batch_size,
seqlen_q,
seqlen_k,
num_heads,
num_heads_k,
head_size,
softmax_scale,
q.dtype());
cudaStream_t stream = dev_ctx.stream();
bool succ = dynload::calc_reduced_attn_scores(q.data(),
k.data(),
softmax_lse.data(),
reduced_scores->data(),
/*softmax_ptr=*/nullptr,
params.batch_size,
params.max_seqlen_q,
params.max_seqlen_k,
params.num_heads,
params.num_heads_k,
params.head_size,
params.softmax_scale,
/*return_softmax=*/false,
params.is_bf16,
/*num_splits=*/0,
stream,
q.strides()[1],
k.strides()[1],
reduced_scores->strides()[1],
q.strides()[2],
k.strides()[2],
reduced_scores->strides()[2],
q.strides()[0],
k.strides()[0],
reduced_scores->strides()[0]);
CheckFlashAttnStatus(succ);
#else
RaiseNotSupportedError();
#endif
}
} // namespace phi
PD_REGISTER_KERNEL(calc_reduced_attn_scores,
GPU,
ALL_LAYOUT,
phi::CalcReducedAttnScoresKernel,
phi::float16,
phi::bfloat16) {}