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288 lines
10 KiB
Python
288 lines
10 KiB
Python
"""
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# Copyright (c) 2025 PaddlePaddle Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""
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from __future__ import annotations
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import paddle
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from paddle.nn.functional import scaled_dot_product_attention
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from fastdeploy.model_executor.layers.attention.base_attention_backend import \
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AttentionBackend
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from fastdeploy.worker.forward_meta import ForwardMeta
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class PaddleNativeAttnBackend(AttentionBackend):
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"""
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The backend class that uses paddle native attention implementation.
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Which is used only for testing purpose.
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"""
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def __init__(self) -> None:
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super().__init__()
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def init_attention_metadata(self, forward_meta: ForwardMeta):
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"""Init the metadata for a forward pass."""
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pass
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def _run_sdpa_forward_extend(
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self,
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query: paddle.Tensor,
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output: paddle.Tensor,
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k_cache: paddle.Tensor,
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v_cache: paddle.Tensor,
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req_to_token: paddle.Tensor,
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req_pool_indices: paddle.Tensor,
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seq_lens: paddle.Tensor,
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extend_prefix_lens: paddle.Tensor,
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extend_seq_lens: paddle.Tensor,
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causal: bool = False,
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) -> paddle.Tensor:
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"""Run the extend forward by using paddle native sdpa op.
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Args:
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query: [num_tokens, num_heads, head_size]
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output: [num_tokens, num_heads, head_size]
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k_cache: [max_total_num_tokens, num_heads, head_size]
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v_cache: [max_total_num_tokens, num_heads, head_size]
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req_to_token: [max_num_reqs, max_context_len]
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req_pool_indices: [num_seqs]
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seq_lens: [num_seqs]
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extend_prefix_lens: [num_seqs]
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extend_seq_lens: [num_seqs]
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causal: bool
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Returns:
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output: [num_tokens, num_heads, head_size]
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"""
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assert seq_lens.shape[0] == extend_prefix_lens.shape[0]
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assert seq_lens.shape[0] == extend_seq_lens.shape[0]
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# [num_tokens, num_heads, head_size] -> [num_heads, num_tokens, head_size]
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# query = query.movedim(0, query.dim() - 2) =>
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query = paddle.transpose(query, perm=[1, 0, 2])
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start_q, start_kv = 0, 0
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for seq_idx in range(seq_lens.shape[0]):
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# TODO: this loop process a sequence per iter, this is inefficient.
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# Need optimize the performance later.
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extend_seq_len_q = extend_seq_lens[seq_idx]
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prefill_seq_len_q = extend_prefix_lens[seq_idx]
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seq_len_kv = seq_lens[seq_idx]
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end_q = start_q + extend_seq_len_q
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end_kv = start_kv + seq_len_kv
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per_req_query = query[:, start_q:end_q, :]
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per_req_query_redudant = paddle.empty(
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(per_req_query.shape[0], seq_len_kv, per_req_query.shape[2]),
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dtype=per_req_query.dtype,
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)
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per_req_query_redudant[:, prefill_seq_len_q:, :] = per_req_query
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# get key and value from cache. per_req_tokens contains the kv cache
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# index for each token in the sequence.
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req_pool_idx = req_pool_indices[seq_idx]
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per_req_tokens = req_to_token[req_pool_idx, :seq_len_kv]
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# per_req_key = k_cache[per_req_tokens].movedim(0, query.dim() - 2)
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# per_req_value = v_cache[per_req_tokens].movedim(0, query.dim() - 2)
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per_req_key = k_cache[per_req_tokens].transpose(
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[query.dim() - 2, 0])
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per_req_value = v_cache[per_req_tokens].transpose(
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[query.dim() - 2, 0])
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per_req_out_redudant = (scaled_dot_product_attention(
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per_req_query_redudant.unsqueeze(0),
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per_req_key.unsqueeze(0),
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per_req_value.unsqueeze(0),
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is_causal=causal,
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).squeeze(0).transpose([query.dim() - 2, 0]))
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output[start_q:end_q, :, :] = per_req_out_redudant[
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prefill_seq_len_q:, :, :]
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start_q, start_kv = end_q, end_kv
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return output
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def _scaled_dot_product_attention(
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self,
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query: paddle.Tensor,
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key: paddle.Tensor,
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value: paddle.Tensor,
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is_causal: bool = False,
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) -> paddle.Tensor:
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"""Paddle implementation of scaled dot-product attention."""
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# query, key, value shape: [batch_size, num_heads, seq_len, head_size]
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d_k = query.shape[-1]
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scores = paddle.matmul(query, key.transpose([0, 1, 3, 2])) # QK^T
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scores = scores / \
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paddle.sqrt(paddle.to_tensor(d_k, dtype=scores.dtype))
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if is_causal:
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# Apply causal mask
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q_len, k_len = scores.shape[-2], scores.shape[-1]
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mask = paddle.triu(paddle.ones((q_len, k_len)) * -1e4, diagonal=1)
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scores += mask.unsqueeze(0).unsqueeze(0)
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attn_weights = paddle.nn.functional.softmax(scores, axis=-1)
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output = paddle.matmul(attn_weights, value)
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return output
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def _run_sdpa_forward_decode(
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self,
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query: paddle.Tensor,
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output: paddle.Tensor,
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k_cache: paddle.Tensor,
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v_cache: paddle.Tensor,
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req_to_token: paddle.Tensor,
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req_pool_indices: paddle.Tensor,
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seq_lens: paddle.Tensor,
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causal: bool = False,
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) -> paddle.Tensor:
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"""Run the decode forward by using paddle native sdpa op.
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Args:
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query: [num_tokens, num_heads, head_size]
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output: [num_tokens, num_heads, head_size]
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k_cache: [max_total_num_tokens, num_heads, head_size]
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v_cache: [max_total_num_tokens, num_heads, head_size]
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req_to_token: [max_num_reqs, max_context_len]
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req_pool_indices: [num_seqs]
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seq_lens: [num_seqs]
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causal: bool
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Returns:
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output: [num_tokens, num_heads, head_size]
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"""
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# [num_tokens, num_heads, head_size] -> [num_heads, num_tokens, head_size]
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query = query.transpose([1, 0, 2])
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start_q, start_kv = 0, 0
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for seq_idx in range(seq_lens.shape[0]):
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# TODO: this loop process a sequence per iter, this is inefficient.
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# Need optimize the performance later.
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seq_len_q = 1
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seq_len_kv = seq_lens[seq_idx]
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end_q = start_q + seq_len_q
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end_kv = start_kv + seq_len_kv
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per_req_query = query[:, start_q:end_q, :]
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# get key and value from cache. per_req_tokens contains the kv cache
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# index for each token in the sequence.
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req_pool_idx = req_pool_indices[seq_idx]
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per_req_tokens = req_to_token[req_pool_idx, :seq_len_kv]
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# [seq_len_kv, num_heads, head_size] -> [num_heads, seq_len_kv, head_size]
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per_req_key = k_cache[per_req_tokens].transpose(
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[query.dim() - 2, 0])
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per_req_value = v_cache[per_req_tokens].transpose(
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[query.dim() - 2, 0])
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per_req_out = (self._scaled_dot_product_attention(
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per_req_query.unsqueeze(0),
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per_req_key.unsqueeze(0),
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per_req_value.unsqueeze(0),
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is_causal=causal,
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).squeeze(0).transpose([query.dim() - 2, 0]))
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output[start_q:end_q, :, :] = per_req_out
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start_q, start_kv = end_q, end_kv
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return output
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def forward_extend(
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self,
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q: paddle.Tensor,
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k: paddle.Tensor,
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v: paddle.Tensor,
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layer: paddle.nn.Layer,
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forward_meta: ForwardMeta,
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save_kv_cache: bool = True,
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) -> paddle.Tensor:
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"""
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Run the prefill and extend(prompt cache) attention forward by using paddle native sdpa op.
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"""
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if layer.qk_head_dim != layer.v_head_dim:
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o = q.new_empty(
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(q.shape[0], layer.self.num_heads * layer.v_head_dim))
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else:
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o = paddle.empty_like(q)
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if save_kv_cache:
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forward_meta.token_to_kv_pool.set_kv_buffer(
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layer, forward_meta.out_cache_loc, k, v)
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q_ = q.view([-1, layer.self.num_heads, layer.qk_head_dim])
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o_ = o.view([-1, layer.self.num_heads, layer.v_head_dim])
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causal = True
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self._run_sdpa_forward_extend(
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q_,
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o_,
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forward_meta.token_to_kv_pool.get_key_buffer(layer.layer_id),
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forward_meta.token_to_kv_pool.get_value_buffer(layer.layer_id),
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forward_meta.req_to_token_pool.req_to_token,
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forward_meta.req_pool_indices,
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forward_meta.seq_lens,
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forward_meta.extend_prefix_lens,
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forward_meta.extend_seq_lens,
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causal=causal,
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)
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return o
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def forward_decode(
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self,
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q: paddle.Tensor,
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k: paddle.Tensor,
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v: paddle.Tensor,
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layer: paddle.nn.Layer,
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forward_meta: ForwardMeta,
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) -> paddle.Tensor:
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"""
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Run the decoding attention forward by using paddle native sdpa op.
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"""
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q = q.reshape([-1, layer.self.num_heads * layer.qk_head_dim])
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if layer.qk_head_dim != layer.v_head_dim:
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o = q.new_empty(
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(q.shape[0], layer.self.num_heads * layer.v_head_dim))
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else:
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o = paddle.empty_like(q)
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forward_meta.token_to_kv_pool.set_kv_buffer(layer,
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forward_meta.out_cache_loc,
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k, v)
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q_ = q.view([-1, layer.self.num_heads, layer.qk_head_dim])
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o_ = o.view([-1, layer.self.num_heads, layer.v_head_dim])
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self._run_sdpa_forward_decode(
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q_,
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o_,
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forward_meta.token_to_kv_pool.get_key_buffer(layer.layer_id),
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forward_meta.token_to_kv_pool.get_value_buffer(layer.layer_id),
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forward_meta.req_to_token_pool.req_to_token,
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forward_meta.req_pool_indices,
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forward_meta.seq_lens,
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causal=False,
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)
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return o
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